Optimizing cation and anion complexity in electrocatalysts expedites oxygen evolution - Dr. Hengzhong Zhang

JANUARY 9, 2023 — A research team led by Dr. Hengzhong Zhang from the Center for High Pressure Science and Technology Advanced Research (HPSTAR) illustrated that the rate-determining step (RDS) of oxygen evolution reaction (OER) could be regulated by simply varying the cation and anion complexity in a family of the metal phosphorous trichalcogenide (MPTC) electrocatalysts (MPT3, where M = Fe, Ni; T = S, Se). Their study unveils the pivotal role of the cation-anion interactions in determining the catalyst performance and provides a simple way for predicting catalytic activities. Their findings were recently published in Angewandte Chemie International Edition (DOI: 10.1002/anie.202214570).

Chemistry under sheer force - Dr. Qingyang Hu

JANUARY 17, 2023 — A collaborated work involved by Yantai University, HPSTAR, Linyi University, ESRF and California State University Northbridge, use a pair of diamond to compress AgI powders to extremely high pressures, equivalent to 420,000 atmospheres. They observed decomposition of AgI into the elementary members of Ag and I. This work is published by the Journal of American Chemical Society Au as a cover story.

​Pressure induced superconductivity in quasi-one-dimensional HfS3 - Dr. Binbin Yue

JANUARY 5, 2023 — Various transition metal trichalcogenides (TMTC) show unique electronic properties, such as metal-insulator transition, topological insulator, and even superconducting transition. Currently, almost all metallic TMTC compounds can show superconductivity either at ambient pressure or at high pressure. However, most TMTC compounds are semiconductors and even insulators. To find out if superconductivity could exist in non-metallic TMTC compound by artificial manipulation, researchers led by Dr. Binbin Yue from HPSTAR and Dr. Fang Hong from Institute of Physics studied the electronic behavior of highly insulating HfS3 and successfully observed the superconducting transition under high pressure. The results reveal that all TMTCs may be superconductors and open a new avenue to explore the abundant emergent phenomena in the TMTC material family. This work is published in the Journal of the American Chemical Society​ (DOI: 10.1021/jacs.2c11184).

Earth's inner core may be oxygen-rich – Drs Jin Liu and Chaojia Lv

DECEMBER 11, 2022 — Oxygen is the key substance for life and one of the most abundant elements in the Earth. However, it’s still unknown whether oxygen is present and in which form in the inner core with extreme high pressure and temperature conditions, and almost composed of pure iron. Scientists co-led by Dr. Jin Liu from HPSTAR, China and Dr. Yang Sun from Columbia University, USA reveal that Fe-rich Fe-O alloys are stable at extreme pressures of nearly 300 GPa and high temperatures of more than 3,000 K. The results published in the journal of The Innovation, prove that oxygen can exist in the solid inner core, which provides key constraints for further understanding of the formation process and evolution history of the Earth_sqlquote_s core.

Crystalline Diamond Nanotherad from Biomass Materials - Drs. Xuan Wang, Kuo Li, and Haiyan Zheng

NOVEMBER 29, 2022 — New research from a team of scientists led by Drs. Kuo Li and Haiyan Zheng from the Center for High Pressure Science and Technology Advanced Research (HPSTAR) firstly found reported the first synthesize of the a three-dimensional atomically ordered crystalline carbon nanothreads (CNThs) can be synthesized from a biomass precursor, 2,5-furandicarboxylic acid (FDCA), through [4+2] Diels-Alder reactions. It The crystalline CNTh shows a goodexcellent electrochemical performance as an anode material of a lithium battery. This work is published on in the Journal of the American Chemical Society (DOI: 10.1021/jacs.2c08914).

Pressure-gated band-edge states of 2D halide perovskites - Dr. Xujie Lü

NOVEMBER 3, 2022 — In For semiconductor heterostructures, reconfiguring the band-edge states and modulating their interplay with charge carriers in a continuous manner have been a long-standing challenge. Recently, an international research team led by Dr. Xujie Lü from the Center for High Pressure Science and Technology Advanced Research (HPSTAR) and Prof. Letian Dou from Purdue University chosen the organic semiconductor-incorporated 2D halide perovskites as a model system. and They discovered that lattice compression induces induced band-alignment switching and charge redistribution, which giving realized controllable emission properties of these 2D hybrid semiconductor heterostructures. The work, entitled “Reconfiguring band-edge states and charge distribution of organic semiconductor-incorporated 2D perovskites via pressure gating", is published in Science Advances.

Aluminous silica: A major water carrier in the lower mantle - Dr. Takayuki Ishii

OCTOBER 26, 2022 — Water is transported by oceanic plates into the Earth_sqlquote_s deep interior and changes the properties of minerals and rocks, affecting the Earth_sqlquote_s internal material cycle and environmental evolution since the formation of the Earth. An international research group led by Dr. Takayuki Ishii and Dr. Ho-kwang Mao (Center for High Pressure Science and Technology Advanced Research, HPSTAR), Bayerisches Geoinstitut, University of Bayreuth, Germany, and Tohoku University, Japan, reveals that aluminous silicas play a major role as a water carrier in the lower mantle. They determined the alumina and water contents of silica minerals, which are important minerals in the basaltic crust of the upper part of a subducting plate.

Pressure Engineering Promising Transparent Oxides – Dr. Wenge Yang

OCTOBER 10, 2022 — New research from a team of scientists co-led by Dr. Wenge Yang from HPSTAR obtained a highly transparent and metastable phase with two orders of magnitude enhancement in conductivity in Ti-doped In2O3 by pressure treatment and thus proposed to apply pressure to modulate the lattice and electronic and optical properties precisely on TCOs. The study is published in Advanced Science.

Ultra mechanical stable Metal-Organic Framework (MOF) - Dr. Zhiqiang Chen

SEPTEMBER 10, 2022 A team of HPSTAR scientists led by Dr. Zhiqiang Chen cooperated with Prof. Zhi Su from Nanjing Normal University found that the mechanical ultra-stability of MOF porous materials depends extensively on their porosity. In this particular work, compared to the amorphization of dense Mn-MOF at 0.8 GPa in a diamond anvil cell, the mechanical stability of porous Mn0.05Fe0.95-MOF has been dramatically enhanced, and the framework integrity could be maintained up to 16.5 GPa. The results are published in the journal of Inorganic Chemistry​.

Capturing high pressures in diamond capsules - Drs. Zhidan Zeng and Charles Zeng

AUGUST 17, 2022 — Preservation of the high-pressure states of materials at ambient conditions is a long-sought-after goal for fundamental research and practical applications. A team of scientists led by Drs. Zhidan (Denise) Zeng, Qiaoshi Zeng, and Ho-Kwang Mao from the Center for High Pressure Science and Technology Advanced Research (HPSTAR) and Prof. Wendy Mao from Stanford University report an innovative breakthrough where they were able to maintain the extraordinary properties of high-pressure materials in free-standing, nanostructured diamond capsules without the support of traditional bulky pressure vessels. Their work​ was recently published in Nature.

A new crystalline-amorphous hybrid structure is found under pressure – Dr. Xujie ​Lü

AUGUST 10, 2022 — Integrating the advantages of crystalline and amorphous states by creating hybrid structures has long been pursued. Recently, a research team led by Dr. Xujie Lü from the Center for High Pressure Science and Technology Advanced Research (HPSTAR) reports the discovery of a new crystalline-amorphous hybrid structure under pressure. Their study, entitled “Nested order-disorder framework containing a crystalline matrix with self-filled amorphous-like innards”, is published in the latest issue of Nature Communications​.

Valence transition in Europium finally confirmed - Dr. Yang Ding

JUNE 27, 2022 — Valence change commonly happens in rare earth metals, while for Eu, it seems an exception in this group of metals. A team of scientists led by Dr. Yang Ding from HPSTAR published a study in the June 27 issue of the journal of Physical Review Letters confirming that a valence transition also occurred in Eu around 80 GPa along with a structural variation. Their study solved a long-standing debate regarding this question.

Hydrous SiO2 in subducted oceanic crust and H2O transport to the core-mantle boundary - Dr. Yanhao Lin

JULY 23, 2022 — New study from a team of scientists co-led by Drs. Yanhao Lin, Qingyang Hu and Ho-kwang Mao from HPSTAR and Michael Walter from Carnegie Institution for Science, first quantified the water storage capacity in stishovite of ~3.5 wt% in the transition zone and shallow lower mantle, decreasing to about 0.8 wt% at the base of the mantle. This study shows that stishovite / post-stishovites as major minerals in deep mantle can host significant amounts of H2O even at high mantle temperatures and provide a unique mechanism for transport and storage of water in the deepest mantle. The research is published in the recent issue of Earth and Planetary Science Letters.

Universal Transitions in Hydrogen Bonds under Extreme Conditions - Dr. Thomas Meier

JUNE 1, 2022 — An international research group led by Dr. Thomas Meier from the Center of High Pressure Science and Technology Advanced Research (HPSTAR) in Beijing, where able to discover a unifying relationship in a number of distinct samples under extreme pressures. In particular, they were able to observe Hydrogen bond symmetrisations in the high-pressure polymorphs ice VII and X, magnesium silicate phase D, as well as in iron bearing and iron free aluminium oxyhydroxides. Employing a novel method of performing Nuclear Magnetic Resonance spectroscopy - a widespread diagnostic for Chemistry and Materials Science – under high pressures, whose development is spear-headed by Dr. Meier and his colleagues, the researchers found that H-bond symmetrisations occur at almost identical distances of the main constituents of the bonds, the oxygen atoms.

Hydrogen heavyweight found for methane-hydrogen compounds - Dr. Ross Howie

MAY 28, 2022 — In recent work published as an Editors’Suggestion in Physical Review Letters, a team led by Dr. Ross Howie, and including HPSTAR (past and present) members Dr. Umbertoluca Ranieri, Dr. Mary-Ellen Donnelly, Dr. Philip Dalladay-Simpson, Prof. Eugene Gregoryanz, and Miss Huixin Hu report the high-pressure formation of the most H2-rich compounds found to date, (CH4)3(H2)25, CH4(H2)2 and (CH4)2H2. Forming above 5 GPa, the compounds exhibit remarkable stability exceeding 160 GPa—about 1.6 million times the atmospheric pressure on Earth.

Simultaneous giant piezoelectricity and ultrahigh coercive field in ferroelectrics - Dr. Gang Liu

MAY 5, 2022 — High-drive electromechanical applications require ferroelectrics accounting for a large coercive field and high piezoelectricity simultaneously but it is still a challenge. Here, a team co-led by Dr. Gang Liu from HPSTAR performs a closely integrated experimental and computational investigations to solve this long-standing puzzle and demonstrate it in a relaxor-based ferroelectric crystal. Their results are published in recent issue of Nature Communications (10.1038/s41467-022-29962-6).

Pressure-Induced Superconductivity in HgTe Single-Crystal Film - Wenge Yang

APRIL 30, 2022 — A team of researchers led by HPSTAR scientist Dr. Wenge Yang has recently used pressure-tuning to discover much richer transport properties emerging in a 400 nm thick bulk HgTe crystal, to rival the unique properties of its thin-film counterpart. Moreover, they also discovered superconductivity in a series of the bulk HgTe’s high-pressure phases. These fascinating results are published in the article “Pressure-Induced Superconductivity in HgTe Single-Crystal Film” in Advanced Science.

High entropy: another dimension for glass states exploration and glassy properties tuning - Dr. Charles Zeng

APRIL 26, 2022 — New study from a team of scientists co-led by Dr. Qiaoshi Zeng from Center for High Pressure Science and Technology Advance Research reported a high-entropy-induced glass-to-glass transition in the NbNiZrTiCo high-entropy metallic glass. This glass-to-glass transition leads to a significant improvement of the modulus, hardness, and thermal stability. Their findings demonstrate that high configurational entropy could be a new dimension for tuning the glass states and properties in multi-component amorphous alloys. This work has recently been published in Nature Communications.

Crystalline tube (3,0) diamond nanothread is synthesized - Dr. Haiyan Zheng

APRIL 20, 2022 — Recently, a research team led by Drs. Ho-kwang Mao, Haiyan Zheng and Kuo Li from Center for High Pressure Science and Technology Advanced Research (HPSTAR) synthesized ultrafine diamond nanothreads with perfect carbon/nitrogen ordered structure through a distinctive reaction of aromatic systems under high pressure, and thus proposed a new method to synthesize more novel structure-specific carbon materials. This work was published on recent Proceedings of the National Academy of Sciences (DOI:10.1073/pnas.2201165119).

Crystal-like glass under pressure - Dr. Qingyang Hu

APRIL 18, 2022 — Glass is everwhere around our life, like glass cup, and it has been made since ancient times. However, we still know very little about its structure in-depth due to confined characterization techniques. By making glass using berlinite crystals as starting materials, the team co-led by Dr. Qingyang Hu from HPSTAR proposed that a remaining topological ordering origin of glass and demonstrated that such topological ordering might hide in many amorphous materials through disordered short atomic displacements. Their work is published in the recent issue of J. Am. Chem. Soc. (doi.org/10.1021/jacs.2c01717 (2022).

Light-induced structural change visualized from time-resolved X-ray diffraction - Dr. Wenge Yang

MARCH 18, 2022 — A research group co-led by Dr. Wenge Yang of HPSTAR, has employed ultrafast laser-initiated time-resolved X-ray diffraction (TR-XRD) (with a time resolution of 79 picosenconds) to directly track the structural evolution of a prototypical two-dimensional (2D) lead-free perovskite (Cs3Bi2Br9) upon photoexcitation. Their work, “Visualizing Light-Induced Microstrain and Phase Transition in Lead-Free Perovskites Using Time-Resolved X‑Ray Diffraction,” was published in the Journal of the American Chemical Society.

Nature Physical Review: High-pressure thermal conductivity - Dr. Xiaojia Chen

FEBRUARY 21,2022 — Measuring and understanding the thermal conductivities of materials is essential for many practical applications we use daily, but what happens under high pressure? A new review paper of Thermal Conductivity of Materials under Pressure published recently in Nature Reviews Physics (online February 21st) by HPSTAR’s Dr. Xiaojia Chen summarizes the recent breakthroughs in high-pressure experimental techniques that have enabled in situ thermal conductivity measurements at extreme pressure-temperature conditions.

Earth's inner core: a mixture of solid Fe and liquid-like light elements - Dr. Duckyoung Kim

FEBRUARY 10, 2022 — ​Over the past several decades, it is widely thought that the Earth inner core is solid composed of iron alloy, but a team of scientists led by Center for High Pressure Science and Technology Advance Research (HPSTAR) and Institute of Geochemistry of CAS (GYIG) suggests that the inner core is not a conventionally known solid but a mixture of solid iron and light-element fluids. Their findings are published February 10 in Nature.

Pressure-driven two-step SHG switching in BiOIO3 - Dr. Yonggang Wang

​JANUARY 18, 2022 — Materials with multi-stabilities controllable by external stimuli are potential for high-capacity information storage and switch devices. Second-harmonic-generation (SHG) as a distinct optical phenomenon is particularly suitable for information storage and readout, nevertheless, pressure-induced multi-step SHG switching material has rarely been reported. A research team led by Dr. Yonggang Wang from HPSTAR in collaboration with Prof. Hongwei Huang from China University of Geosciences (Beijing) reported the first example of a pressure-driven two-step SHG switching in polar BiOIO3. These findings were recently published in Angew. Chem. Int. Ed.

A 'Gear-Spring' structure with anomalous compressibility – Drs. Ting Wen and Yonggang Wang

JANUARY 18, 2022 — Materials with zero-linear compression (ZLC) and zero-area compression (ZAC) hold great promises for specific applications retaining constant in specific directions or planes under external impaction. Up to now, no more than ten ZLC/ZAC materials have been reported, most of which are of very limited working pressure ranges (< 10 GPa). Herein, a pioneering work led by Dr. Ting Wen and Dr. Yonggang Wang from HPSTAR reports their discovery of an intrinsic ZLC/ZAC property in Li2Ti(IO3)6 with a new “Gear-Spring” type structure over an ultra-wide pressure range (up to 40 GPa). The results have been published online in recent CCS Chemistry.

​Depressed 660-km discontinuity caused by akimotoite-bridgmanite transition - Dr. Takakuki Ishii

JANUARY 6, 2022 — New work from a team of scientists co-led by Dr. Takayuki Ishii from HPSTAR reported that the large depressions of the 660-kilometre discontinuity in cold subduction zones is related to an extremely steep akimotoite-bridgmanite transition at low temperatures. The slab stagnation may also be casued by the significant upward buoyancy casued from this deeper and delayed transtion in the slab. The study is published in the recent issue of the journal of Nature.

Crystalline Fully Carboxylated Polyacetylene Obtained under HP as a Li-Ion Battery Anode Material – Dr. Haiyan Zheng

DECEMBER 28, 2021 — New research by a team led by Dr. Haiyan Zheng from HPSTAR reports a completely functionalized crystalline polyacetylene produced using high-pressure techniques - the first crystalline poly-dicarboxylacetylene with every carbon on the trans-polyacetylene backbone bonded to a carboxyl group. Its unique structure combines the extremely high content of carbonyl groups and high conductivity of a polyacetylene backbone, exhibiting high specific capacity, high Coulombic efficiency and excellent cycling/rate performance as a LIB anode. This work is published in the latest edition of the Journal of Physical Chemistry Letters.

Mechanical on–off photoluminescence in hybrid metal halides - Dr. Yonggang Wang

DECEMBER 25, 2021 — Stimulus-responsive photoluminescent materials have attracted extensive research attention in recent years owing to their potential application in information storage and switch devices. Most of the materials that exhibit such phenomena are small organics, organometallic materials, liquid crystals, or polymer networks. At present, materials with high pressure sensitivity and high contrast are still in short supply. Recently, new work from a research team co-led by Prof. Jing Zhao from University of Science and Technology Beijing (USTB) and Dr. Yonggang Wang from HPSTAR reported their discovery of hybrid metal halides exhibiting stimulus-responsive photoluminescence (PL) phenomenon. Their results were published online recently in Adv. Funct. Mater.

Echo of water from 1200 km depth below our feet - Dr. Qingyang Hu

DECEMBER 15, 2021 — New study from a team of scientists led by Dr. Qingyang Hu found that the high-conductivity and low-sound velocity of ε-FeOOH matched the features of heterogenous scatterers in the mid-lower mantle and such unique properties of hydrous ε-FeOOH, or possibly other Fe-enriched phases could be detected as evidence of active water transportation in the mid-lower mantle.

The diamond barometer - Drs. Qingyang Hu and Ho-Kwang Mao

DECEMBER 15, 2021 — By combining the ultrasonic interferometry and multianvil press, a team of scientists led by Dr. Qigyang Hu from HPSTAR extended the research of diamond_sqlquote_s elasticity from kilobar to gigapascal pressures and showed that diamond became increasingly compressible, reaching agreement with theory. They pointed out the unique potential of diamond in providing an accurate, absolute pressure standard up to the terapascal region, which would be the basis cornerstone of the extensive, high-pressure sciences.

Synthesis of Paracrystalline Diamond: Discovering the Rosetta Stone of Non-crystalline Materials - Dr. Huiyang Gou

NOVEMBER 25, 2021 — A team of researchers by Dr.Huiyang Gou from HPSTAR and Dr. Howard Sheng from George Mason University in collaboration with Prof. Tomo Katsura at University Bayreuth, Prof. Mingsheng Wang at Xiamen University and Dr. Zhidan Zeng at HPSTAR, have discovered a new form of diamond that could fundamentally challenge our ideas about the nature of solids. This new member of the enriched carbon family could be further exploited to create new materials and has profound implications for recognising complex structures arising from amorphous materials. Detailed results are published in the latest edition of Nature​.

Pressure induced metallization and superconductivity in the van der Waals compound CuP2Se – Dr. Hengzhong Zhang

NOVEMBER 24, 2021 — A research team led by Dr. Hengzhong Zhang from the Center for High Pressure Science and Technology Advanced Research (HPSTAR) revealed that a new Cu-bearing van der Waals compound CuP2Se can be metallized and then turned into a superconductor accompanying a series of structural changes under compression. Their study illustrates that pressure can be used to harvest useful physical and chemical properties of Cu-bearing vdWs materials. These findings were recently published in the Journal of the American Chemical Society.

Pressure-gradient-driven MnOOH dehydrogenation and prototype battery - Dr. Kuo Li

NOVEMBER 20, 2021 — New work by a team of scientists led by Dr. Kuo Li and Dr. Haiyan Zheng from HPSTAR have found that pressure gradients across various hydrogen-bearing compounds, such as γ-MnOOH, can promote dehydrogenation. The team proposes a pressure-gradient-driven battery through this process by separating the transferring routes of protons and electrons. The results are published in the Journal of Physical Chemistry Letters.

Oxygen controls on magmatism in rocky exoplanets - Drs. Yanhao Lin and Ho-Kwang Mao

​NOVEMBER 4, 2021 — New work published in the Proceedings of the National Academy of Sciences by HPSTAR’s Yanhao Lin and Ho-Kwang “Dave” Mao — with collaborator Wim van Westrenen of Vrije Universiteit Amsterdam — demonstrates that oxygen is essential for rock to melt, and the more oxygen you add to rock, the more easily you can make magma.

Density-change-driven superconductivity in amorphous solids - Drs. Kai Zhang, Nana Li and Wenge Yang

SEPTEMBER 16, 2021 — The correlation between superconductivity and a disordered structure is an interesting and challenging topic in condensed matter physics. Although scientists discovered amorphous superconductors as early as 1954, their superconducting mechanism has remained mysterious due to their complex chemical and structural disorder, and limited investigative experimental techniques under extreme conditions. Recently, a new work from a research team led by Dr. Wenge Yang of HPSTAR (Center for High Pressure Science &Technology Advanced Research) in collaboration with Prof. Ming Xu of Huazhong University of Science and Technology, and Prof. Matthias Wuttig of RWTH Aachen University uncovered a close relationship between superconductivity and density in amorphous solids. Detailed results are published in the recent issue of Physical Review Letters.

Putting the squeeze on hydrogen-bonding in HCl – Dr. Philip Dalladay-Simpson

SEPTEMBER 6, 2021 — In a truly international effort, a team of scientists based in Japan, Australia, UK, USA and China have uncovered the high-pressure behavior of hydrogen chloride (HCl). The project, which was led by Dr. Philip Dalladay-Simpson of HPSTAR, details the significant role that hydrogen still plays even after the pressure-induced symmetrisation of the hydrogen bond in HCl. The team’s findings, which were published in Science Advances, will have implications for our understanding of warm hydrogen-dominant matter under extreme pressures and is therefore highly relevant to planetary interiors.

Pressure engineered Sb2S3 for better semiconductors – Dr. Qingyang Hu

SEPTEMBER 2, 2021 — Semiconductors were widely used in manufacturing chops, solar cells, photovoltaic devices and so on, which have defined the third industrial revolution since the late 1900s. Although a large number of semiconductor materials are in production, people are still seeking new semiconductor materials with higher energy conversion efficiency. Choices for environmentally friendly and affordable semiconductors are limited. However, it is possible to optimize the properties of semiconductor materials through doping, preparing thin films, and high-temperature annealing. Here, we introduce an effective, energy-efficient and pollution-free approach to continuously modulate the band gap of Sb2S3 at gigapascal pressures by means of hydrostatic pressure compression. The research is published in Communications Chemistry.

Discovery of carbon-based strongest and hardest amorphous material – Dr. Alex Soldatov

AUGUST 20, 2021 — Carbon exhibits a vast variety of allotropic forms stemming from its different chemical bonding motifs - from well-known graphite and diamond, to fullerenes and carbon nanotubes build of nanometer-sized structural units. In this row diamond possesses a “special” place being the hardest known natural material on Earth. This status-quo remained until a research team from Yanshan university led by Prof. Yongjun Tian in collaboration with Prof. Alex Soldatov of HPSTAR produced for the first time a nearly pure sp3-bonded amorphous carbon that is harder than- and equally strong as natural diamond. The material termed AM-III, is a transparent semiconductor with a bandgap of 2.2 eV. It surpasses in hardness and fracture toughness all known amorphous materials. This work is presented in the August issue of National Science Review.

Pressure Induced Topochemical [4 + 2] Dehydro-Diels−Alder (DDA) Reaction- Yapei Li, Drs. Haiyan Zheng and Kuo Li

JULY 23, 2021 — New work from a team of scientists led by Dr. Haiyan Zheng and Dr. Kuo Li from HPSTAR found the ethynylphenyl of 1,3,5-triethynylbenzene (TEB) undergoes [4 + 2] dehydro-Diels−Alder (DDA) reaction with phenyl at 4 GPa. Their study suggested that the DDA reaction between ethynylphenyl and phenyl is a promising route to decrease the reaction pressure of aromatics, which allows the scalable high-pressure synthesis of nanoribbon materials. The result is published recently in the Journal of Physical Chemistry Letters.

Yolk-Shell Nanoarchitecture for Stabilizing a Ce2S3 Anode - Dr. Mingxue Tang

JULY 19, 2021 — A team of HPSTAR scientists led by Dr. Mingxue Tang has developed Stöber sol-gel method and in-shell sulfuration method craft γ-Ce2S3 nanoparticles in hollow mesoporous carbon shell with tunable voids to buffer the volume change upon electrochemical cycling for the first time. The synergetic effects of nanosized Ce2S3 core and the coating carbon shell with enhanced electronic conductivity offer enhanced rate performance. The working mechanism is unraveled with ex-situ XRD and NMR characterizing techniques. The work is published in the journal of Carbon Energy.

Metallization of Quantum Material GaTa4Se8 at High Pressure - Drs. Hongshan Deng and Yang Ding

​JUNE 15, 2021 — A team of HPSTAR scientists led by Dr. Yang Ding and Dr. Hongshan Deng has solved a thirty-year mystery regarding the insulator-to-metal transition in the quantum molecular compound GaTa4Se8(GTS), a material that could revolutionize computer memory as a resistive RAM. Using new methods integrating electrical resistance with Raman spectroscopy at high pressure, they observed an extraordinary range of material phases in GaTa4Se8 at previously unattainable pressures above 50 GPa. "Metallization of Quantum Material GaTa4Se8 at High Pressure" is published in the latest edition of the Journal of Physical Chemistry Letters as a supplementary journal cover.

Dry metastable olivine and slab deformation in a wet subducting slab - Dr. Takayuki Ishii

MAY 25, 2021 — While the plates carry water to the Earth_sqlquote_s interior, phase transitions of dry olivine, the main mineral in the plates, are thought to be responsible for deep-focus earthquakes and plate deformation. This study resolves the contradiction of the presence of dry olivine even in wet plates. Takayuki Ishii, a staff scientist of HPSTAR, and Eiji Otani, professor emeritus at Tohoku University, used high-pressure and high-temperature experiments to determine the water content of olivine under the conditions of a subducting plate containing water. The results show that the hydrous minerals absorb water, while the coexisting olivine contains no water at all. This experimental result overturned previous theories on the role of hydrous minerals, and revealed that deep-focus earthquakes can occur even in a wet plate, and that large plate deformation can also occur.The results of this research is published in Nature Geoscience.

Rethinking the Design of Ionic Conductors Using Meyer–Neldel–Conductivity Plot - Drs. Nana Li and Wenge Yang

MARCH 25, 2021 — Recently, a team of scientists co-led by Prof. Shouhang Bo from Shanghai Jiaotong University and Wenge Yang from HPSTAR (Center for High Pressure Science & Technology Advanced Research) proposed to use the Meyer-Neldel-Conductivity plot to design fast ionic conductors with improved conductivity. They stated that the Meyer-Neldel-Conductivity plot is a universal principle that can be used to all ionic conductors for improving ionic conductivity. The results are published in the recent issue of Advanced Energy Materials (DOI: 10.1002/aenm.202100325).

Earth's deep mantle may have proton rivers made of superionic phases- Drs. Jin Liu,Duckyoung Kim and Qingyang Hu

MARCH 9, 2021 — Although three-quarters of Earth’s surface is covered by water, standalone water or ice rarely exists in Earth’s interiors. The most common unit of “water” is hydroxyl, which is associated with host minerals to make them hydrous minerals. Here, a research group led by Dr. Qingyang Hu, Dr. Duckyoung Kim, and Dr. Jin Liu from the Center for High Pressure Science and Technology Advanced Research discovered that one such hydrous mineral also enters an exotic superionic phase, similar to water ice in giant planets. The results are published in Nature Geosciences.

Pressure-regulated excitonic features enhance optoelectronic property in 2D halide perovskites - Dr. Xujie Lü

MARCH 1, 2021 — Two-dimensional (2D) halide perovskites have recently emerged for photovoltaic and optoelectronic applications due to their unique and tunable properties. Despite substantial progress being made on the development of these materials, critical questions remain, such as how the structural regulation affects their excitonic features which govern the optoelectronic properties of 2D halide perovskites. Addressing these challenges calls for better understanding of fundamental mechanisms.

Stable armchairlike hexazine N6 ring in Tungsten Hexanitride – Drs. Nilesh Salke and Jin Liu

FEBRUARY 9, 2021 — Tungsten hexanitride with armchairlike hexazine N6 ring has been synthesized by a group of scientists led by Dr. Jin Liu and his former postdoc Nilesh Salke at HPSTAR (Center for High Pressure Science & Technology Advanced Research). WN6 is a promising high-energy-density and superhard material. Their findings are published in the recent issue of Physical Review Letters (doi: https://doi.org/10.1103/PhysRevLett.126.065702).

First direct band gap measurements of wide-gap hydrogen using inelastic X-ray scattering - Drs. Bing Li and Ho - Kwang Mao

JANUARY 25, 2021 — Utilizing a newly developed state-of-the-art synchrotron technique, a group of scientists led by Dr. Ho-kwang Mao, Director of HPSTAR, conducted the first-ever high-pressure study of the electronic band and gap information of solid hydrogen up to 90 GPa. Their innovative high pressure inelastic X-ray scattering result serves as a test for direct measurement of the process of hydrogen metallization and opens a possibility to resolve the electronic dispersions of dense hydrogen. This work has been published in the recent issue of Physical Review Letters.

Regulating off-centering distortion maximizes photoluminescence in halide perovskites - Dr. Xujie Lü

DECEMBER 21, 2020 — In work published in the journal of National Science Review (Regulating off-centering distortion maximizes photoluminescence in halide perovskites, https://doi.org/10.1093/nsr/nwaa288). a team at HPSTAR led by Dr. Xujie Lü applied high pressure to tune the remarkable photoluminescence (PL) properties in halide perovskites. For the first time, they reveal a universal relationship whereby regulating the level of off-centering distortion (towards 0.2) can achieve optimal PL performance.

Potential extreme condition history detector — recoverable tricolor PL achieved through pressure induced site symmetry breakdown in pyrochlore - Drs. Yongsheng Zhao and Wenge Yang

DECEMBER 11, 2020 — Photoluminescence (PL) is light emission from a substance after the absorption of photons stimulated by temperature, electricity, pressure, or chemistry doping. An international team of scientists led by Dr. Wenge Yang from Center for High Pressure Science &Technology Advanced Research (HPSTAR) presents a strong tricolor PL achieved in non-PL pyrochlore Ho2Sn2O7 through high pressure treatment. Interestingly the PL can be much enhanced after pressure release and recovered to ambient conditions. Their study is published in the recent issue of Physical Review Letters.

The heavier, the better — superior stability in isotope functionalized perovskites - Drs. Gang Liu and Lingping Kong

DECEMBER 4, 2020 — New work from a team of scientists led by Drs. Gang Liu and Lingping Kong from HPSTAR employed high pressure tools to discover a significantly suppressed lattice disorder in isotope functionalized perovskite MAPbI3, which is crucial for structural stability and extraordinary optoelectronic properties. Such improved lattice stability boosts its photoluminescence intensity by 3 folds previously unachievable without isotope doping. The result is published recently in Advanced Functional Materials.

Temperature and rate-dependent formation of metastable silicon- Dr. Chuanlong Lin

OCTOBER 10, 2020 — New work from a team of scientists led by Dr. Chuanlong Lin from HPSTAR revealed two distinctive transition pathways, a thermally-activated crystal-crystal transition and a mechanically-driven amorphization, in the structural evolution of high-pressure metallic β-Sn silicon (Si-II) under rapid decompression at various temperatures. The study is published in the recent issue of Physical Review Letters.

​Pressure induced topochemical Dehydro-Diels-Alder reaction – Drs. Kuo Li, Haiyan Zheng and Peijie Zhang

SEPTEMBER 28, 2020 — New work from a team of scientists led by Drs. Kuo Li and Haiyan Zheng from HPSTAR collaborated with Dr. Jing Ju from Peking University found pressure-induced polymerization of 1, 4-diphenylbutadiyne (DPB) produces crystalline graphitic nanoribbons. Their study shows the topochemical reaction route of DPB starts from the Dehydro-Diels-Alder (DDA) reaction instead of the traditional 1,4-addition reaction. The result is published recently in Journal of the American Chemical Society​.

Aberrant electronic and structural alterations in pressure tuned perovskite NaOsO3 - Drs. Raimundas Sereika and Yang Ding

SEPTEMBER 18, 2020 — ​The perovskite NaOsO3 has a complicated, but interesting temperature dependent metal-insulator transition (MIT). A team led by Drs. Raimundas Sereika and Yang Ding from the Center for High Pressure Science and Technology Advanced Research (HPSTAR) showed that the insulating ground state in NaOsO3 can be preserved up to at least 35 GPa with a sluggish MIT reduction from 410 K to a near room temperature and possible transformation to a polar phase. The work published in the npj Quantum Materials.

Reaching 90% Photoluminescence Quantum Yield in 1D Metal Halide by Pressure-Suppressed Nonradiative Loss- Drs. Xujie Lü and Wenge Yang

SEPTEMBER 16, 2020 — An international team led by Dr. Xujie Lü and Dr. Wenge Yang from the Center for High Pressure Science and Technology Advanced Research (HPSTAR) discovered that pressure can sufficiently suppress the non-radiative loss in 1D metal halide C4N2H14PbBr4, and lead to the photoluminescent quantum yield (PLQY) increasing from initial 20% to over 90% at 2.8 GPa .

Band gap crossover and metallization in the compressed CrPS4 - Drs. Resta Susilo and Bin Chen

AUGUST 20, 2020 — In a new work, an international team led by Drs. Resta Susilo, Bo Gyu Jang, DuckYoung Kim and Bin Chen from HPSTAR reported a band gap crossover which is successively followed by an insulator-metal transition in the vdW antiferromagnetic insulator CrPS4 under pressure. The result is published recently in npj Quantum Materials.

Pressure-induced 2D-3D conversion in hybrid lead iodide layered perovskite -Drs. Lingping Kong and Gang Liu

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JULY 20, 2020 — Hydrostatic pressurization can effectively lead to new and improved material properties. However, most of the novel material properties are only retainable at high-pressure states, and therefore warrant no practical applicability at ambient conditions. Recently, a team of international scientists led by Dr. Lingping Kong and Dr. Gang Liu from HPSTAR reported permanent and irreversible transition of 2D hybrid Dion-Jacobson lead iodide perovskite to 3D perovskite phase at ambient conditions after pressure treatment. This work suggests the usefulness of high-pressure technique in preparing materials for real-

Pressure suppresses carrier trapping in 2D halide perovskite - Drs. Wenge Yang & Dr. Xujie Lü

JULY 17, 2020 — An international team led by Dr. Xujie Lü and Dr. Wenge Yang from the Center for High Pressure Science and Technology Advanced Research (HPSTAR) discovered that lattice compression under a mild pressure considerably suppresses the carrier trapping of a 2D perovskite (HA)2(GA)Pb2I7, leading to significantly enhanced emission. Intriguingly, a new phase obtained after pressure-treatment possesses a higher crystallographic symmetry, fewer trap states, and enhanced PL intensity. The findings were recently published in Angew. Chem. Int. Ed.

A new two-dimensional carbon allotrope — semiconducting diamane film synthesized - Dr. Feng Ke,Lingkong Zhang & Dr. Bin Chen

JUNE 25, 2020 — Regulating the phase transition process of carbon materials under high pressure and high temperature is always a straightforward method for achieving diamondization. Here, a team of scientists led by Drs. Feng Ke and Bin Chen from HPSTAR (the Center for High Pressure Science and Technology Advanced Research) used this direct approach, diamondization of mechanically exfoliated few-layer graphene via compression, to synthesize the long-sought-after diamane film. The study is published in Nano Letters.

Order out of disorder in ice - Drs. Chuanlong Lin and Wenge Yang

JUNE 23, 2020 — The glass structure of a material is often believed to mimic its corresponding liquid. Polyamorphism between ices has been used as a guide to elucidate the properties of liquid water. But how many forms of amorphous ices are there? Do we understand how metastable high-pressure crystalline ice evolves towards the thermally stable low-density form? An international research team led by Chuanlong Lin and Wenge Yang from HPSTAR has revealed a multiple-step transformation mechanism using state-of-the-art time-resolved in situ synchrotron x-ray

Scientists Discovered a Long-sought-after Allotrope of Nitrogen in Black Phosphorus Structure - Drs. Cheng Ji, Huiyang Gou and Ho-Kwang Mao

JUNE 5, 2020 — An international team co-led by Ho-Kwang Mao and Huiyang Gou from Center for High Pressure Science and Technology Advanced Research (HPSTAR) and Yansun Yao from University of Saskatchewan discovered that nitrogen, usually consisting of diatomic molecules, can form an extended structure under the conditions of 1.5 million atm pressure and 1,900 °C. In the new structure, all nitrogen atoms are connected with single bonds, similar to phosphorus atoms in black phosphorus (BP). This finding provides prospects for nitrogen-based two-dimensional (2D) materials. The results were recently published in Science Advances.

Counterintuitive phase behaviour observed in isotopic hydrogen (H2-HD-D2) alloys - Drs. Philip Dalladay-Simpson and Ross Howie

JUNE 02, 2020 — In an international collaboration of scientists based at HPSTAR, Hefei institute of Solid-state physics and the University of Edinburgh, the phase diagram of the fundamental ternary molecular alloy, bearing isotopes: hydrogen (H2) deuterium (D2) and hydrogen deuteride (HD), was carried out to the most extreme conditions, up to 200 GPa and down to 13 K. These extensive measurements, which are the first of their kind and published in a recent issue of PNAS, implemented in-situ high-pressure low-temperature Raman spectroscopy to identify and constrain phase transitions within these alloys over broad

Oxygen-excess oxides in Earth's mid-mantle facilitate the ascent of deep oxygen – Drs. Jin Liu, Qingyang Hu and Ho-Kwang Mao

MAY 27, 2020 — ​Subduction of hydrous materials imposes a great influence on the structure, dynamics, and evolution of our planet. However, it is largely unclear how subducting slabs chemically interact with the middle mantle. Recently, an oxygen-excess phase (Mg,Fe)2O3+δ was discovered under the Earth’s middle mantle conditions (~ 1000-2000 km) by a team of scientists from the Center of High Pressure Science and Technology Advanced Research (HPSTAR) and Stanford University. This oxygen-excess phase is fully recoverable to ambient conditions for ex-situ investigation using transmission electron microscopy. It contains

The lower mantle can be oxidized in the presence of water - Drs. Qingyang Hu, Jin Liu & Ho-Kwang Mao

MAY 13, 2020 — If we took a journey from Earth’s surface to the center, the midway point locates roughly at 1900 km depth in the lower mantle. The lower mantle ranges from 660 to 2900 km depth and occupies 55% of our planet by volume. The chemical composition of the lower mantle is rather simple. It has long been pictured as being made up of 2 major minerals (~95%), namely bridgmanite and ferropericlase. Until recently, this neat model is directly challenged by a set of discoveries in the lower mantle.

New light shed on the origin of plasticity in nanostructured silicon - Dr. Zhidan Zeng

MAY 11, 2020 — How does nanostructured silicon deform has been the subject of a long-standing debate over the past decade. Now recent research from a team of scientists led by Dr. Zhidan Zeng from HPSTAR clarifies that pressure-induced phase transitions play a key role in the plastic deformation of compressed silicon nanoparticles. Their findings are reported in Physical Review Letters (DOI: 10.1103/PhysRevLett.124.185701).

New type of morphotropic phase boundary in ferroelectrics - Drs. Gang Liu andLingping Kong

MAY 7, 2020 — New study led by Dr. Gang Liu from HPSTAR reported a new type of morphotropic phase boundary (MPB) in relaxor-PbTiO3 crystals. Such a novel MPB, referred as “diffused MPB”, results in both high piezoelectricity and thermal stability simultaneously, which is critical for the applications of ferroic materials. This work redefines the core concept in ferroelectrics, and opens a new way for future ferroic materials. The study is published in the flag journal of American Institute of America (AIP), Applied Physics Reviews, which is selected as a featured paper and is highlighted by Scilight which showcases the most interesting research across the physical sciences published in AIP Publishing Journals.

Complex hydrogen substructure in semimetallic ruthenium tetrahydride - Drs. Ross Howie, Philip Dalladay-Simpson and Duckyoung Kim

APRIL 26, 2020 — The search for polyhydride materials at high pressure has produced numerous predictions focused almost entirely on metallic superconductors. Intriguingly, a series of independent studies have postulated the anomalous emergence of semiconducting and semimetallic polyhydrides unique to the group 8 metals Fe, Ru, Os. Despite extensive study these materials have remained entirely hypothetical to date. A new study, comprised primarily of HPSTAR researchers, report on the discovery and properties of two novel ruthenium polyhydride materials – Ru3H8 and RuH4. This study is published in the Journal of Physical Chemistry Letters (https://doi.org/10.1021/acs.jpclett.0c00688).

Quasi-reconstructive phase transition in ZnTe - Dr. Qingyang Hu

MARCH 5, 2020 — New study from a team of scientists led by Dr. Qingyang Hu and Prof. Shengcai Zhu from Sun Yat-sen University found a quasi-reconstructive phase transition in ZnTe under different stress conditions. While phase transitions come in either displacive or reconstructive type, it occurs simultaneously in ZnTe when it was under pressure. The special type of phase transition reveals a previously undefined “grey zone” in the well-established phae transition theories. Upon the transition, ZnTe shows narrowed electronic bandgap, which provides insights for materials design and engineering in II-VI semiconductors. The study is published in the Journal of Materials Chemistry C.

The smaller, the stronger - Dr. Bin Chen

FEBRUARY 25, 2020 — According to the well-known Hall-Petch relationship, the strength of nanometals decreases when the grain size is smaller than 10 to 15 nanometers. New high-pressure compression study from a team of scientists led by Dr. Bin Chen from HPSTAR and Prof. Xiaoxu Huang from Chongqing University detected the strengthening in nano-grained nickel down to 3 nanometers. The yield strength of the 3-nanometer-grain-size sample is ten times greater that of a common commercial nickel material. The work is published in Nature [DOI: 10.1038/s41586-020-2036-z].

Near room-temperature 2D ferromagnetic metal – Dr. Duckyoung Kim

​JANUARY 18, 2020 — New study from a team of scientists co-led by Dr. Duckyoung Kim from HPSTAR synthesized a new iron-based 2D ferromagnetic metal material, Fe4GeTe2 with the help of theoretical design. This new 2D ferromagnetic metal shows a nearly room temperature ferromagnetic order, together with a large magnetization and high conductivity and these properties could be retained in cleaved crystals down to seven layers. Their study highlights that Fe4GeTe2 and its nanometer-thick crystals as a promising candidate for spin source operation at nearly room temperature and hold promise to further improves the magnetic properties of vdW ferromagnets by theory-guide. The work is published in the recent issue of Science Advances.

Two-way tuning of structural order in metallic glasses – Drs. Hongbo Lou and Qiaoshi Zeng

JANUARY 17, 2020 — Metallic glasses are disordered alloys with many properties superior to conventional crystalline metals. Unlike crystalline materials that follow strict atomic-packing rules and imposed symmetry, in principle, metallic glasses have a high degree of freedom to arrange their atoms with almost infinite possibilities in their configuration space. However, in practice, effectively modulating the disordered structures of metallic glasses is rather challenging. A new study from a team of scientists led by Dr. Qiaoshi Zeng from HPSTAR realized a two-way tuning of structures between distinct states in metallic glasses by combining temperature and pressure. Their results are published in the Jan. 16th issue of Nature Communications (DOI: 10.1038/s41467-019-14129-7).

Pressure induced novel superstructure-phase in 1T-VSe2 - Drs. Raimundas Sereika and Yang Ding

JANUARY 3, 2020 — New work from a team of scientists led by Dr. Yang Ding from HPSTAR discovered a novel superstructure in 1T-type vanadium diselenide (VSe2) that ​converts sample from two-dimensional to three-dimensional at pressures >16 GPa (room temperature). They revealed that the pressure-induced superstructure is driven by the Fermi-surface nesting and at the same time enhanced by vanadium atoms displacement. The results are published in the Journal of Physical Chemistry Letters.

Ultrahydrous stishovite in Earth's lower mantle - Drs. Qingyang Hu and Ho-kwang Mao

DECEMBER 17, 2019 — New study from a team of scientists co-led by Drs. Qingyang Hu and Ho-kwang Mao from HPSTAR, discovered that stishovite — a major mineral in deep mantle, can incorporate large amounts of water in its crystal structure and the hydrous stishovite may be a key phase for transporting and storing water in earth lower mantle. The research is published in the recent issue of the journal Proceedings of the National Academy of Sciences.

Synthesis of high quality highest-boron molybdenum boride with multi-functionalities - Drs. Huiyang Gou and Xiang Gao

DECEMBER 15, 2019 — New study from a team of scientists led by Dr. Huiyang Gou of HPSTAR reported the synthesis of high-quality single crystal of molybdenum boride by multianvil technique, which enables the understanding of long-standing uncertainties in structure and composition about this highest boride in Mo-B system. The superior mechanical properties and superconductivity were revealed unambiguously. Their study is published in recent issue of Chem. Mater. (10.1021/acs.chemmater.9b04052).

Review: Anti-Perovskites with Exceptional Functionalities - Dr. Yonggang Wang

DECEMBER 14 — After long-term ploughing and weeding on functional materials with anti-perovskite structure, a joint group of scientists co-led by Dr. Yonggang Wang from HPSTAR, published a review paper on anti-perovskites with exceptional functionalities on Adv. Mater. (doi:10.1002/adma.201905007). This Review summarized recent advances in novel anti-perovskite materials with exceptional functionalities, including superionic conductivity, superconductivity, giant magnetoresistance and negative thermal expansion. Particularly, a universal strategy for enhancing the performance in anti-perovskites is discussed from the perspective of solid-state chemistry. With more research enthusiasm, anti-perovskites are highly anticipated to be a rising star within functional materials.

Probes the Volume Collapse in Rare-earth Metal with Inelastic X-ray - Drs. Bijuan Chen and Yang Ding

DECEMBER 10, 2019 — Understanding the mechanism of volume collapse phenomena in rare-earth materials remains an important challenge in part due to lack of direct information on 4f electronic structures at highpressures. A group of scientists led by Dr. Yang Ding of HPSTAR, reported the first high-pressure inelastic x-ray scattering measurement on elemental cerium (Ce) metal. Their work revealed the critical role of 4f-5d Kondo coupling across the volume collapse, whereas anther proposed Hubbard model appears to play a minor role. This study is published in the Journal of Physical Chemistry Letters.

Combined concomitant IR-Raman measurement on hydrogen phase IV - Drs. Cheng Ji and Ho-kwang Mao

DECEMBER 3, 2019 — New study from a team of scientists co-led by Dr. Cheng Ji and Dr. Ho-kwang Mao from HPSTAR performed the first combined infrared-Raman experiments on hydrogen phase IV, up to 280 GPa. By utilizing an advanced spectroscopy system which incorporates synchrotron Infrared (IR) spectroscopy and Raman spectroscopy at Shanghai Synchrotron Radiation Facility and toroidal diamond anvils, they revisited phase IV in its molecular symmetry and revealed heterogeneous and fluxional behaviors. The study has been published in the recent issue of PNAS.

Pressure May Be Key To Fighting Climate Change With Thermoelectric Generators- Dr. Xiaojia Chen

OCTOBER 7, 2019 — New study from a team of scientists led by Dr. Xiaojia Chen from HPSTAR found that pressure can improve the ability of materials to turn heat into electricity and could potentially be used to create clean generators. The work is published in Nature Materials.

Synthesis of superconducting cerium superhydride with 3D atomic hydrogen sublattice - Dr. Nilesh P. Salke

OCTOBER 2, 2019 — Hydrogen-rich superhydrides are very promising candidates to achieve superconductivity close to room temperature. Most of the superhydrides stabilize at very high pressures. A team of scientist led by Dr. Nilesh P. Salke at the Center for High Pressure Science and Technology Advanced Research (HPSTAR) has discovered the cerium superhydride CeH9 at 80-100 GPa with laser heating. CeH9 possess the atomic hydrogen sublattice which is the closest analogue to metallic hydrogen at 100 GPa. This study is published in recent Nature Communications.

Under pressure: Viewing how hydrogen transforms- Drs. Cheng Ji and Ho-Kwang Mao

SEPTEMBER 26, 2019 — An international team led by HPSTAR director Dr. Ho-Kwang Mao succeeded in determining how hydrogen molecules are packed at extremely high pressures. Their work solved the long-standing mystery of what is the structure of the dense form of hydrogen, called phase IV (Roman numeral four). This work is published in Nature.

Pressure-induced inverse photoconductance in WO3/CuO heterostructure - Dr. Lin Wang

AUGUST 15, 2019 — New study from a team of scientists led by Dr. Lin Wang of HPSTAR find pressure can effectively tune the photoreponses of nano heterojunction. They found a reversible inverse photoconductivity transition in WO3/CuO heterostructure under high pressure. Their study may provide an applicable tool with enhanced performance for photovoltaic devices, functioning as a switch, controller, or a potential light absorber and especially solar water splitting and solar degradation of organic pollutants in future. The study is published in recent Advanced Science.

Highly reversible oxygen redox promoted by manganese site vacancy - Dr. Mingxue Tang

JULY 22, 2019 — Extra capacity can be achieved by the redox of oxygen anions in addition to the redox of transition metals (Li/Na rich cathodes). However, the challenges remain in Li/Na rich cathodes are the reversible oxygen redox and the voltage decay/ hysteresis. A team of scientists co-led by Dr. Mingxue Tang from HPSTAR systematically investigated the mechanism behind the highly reversible oxygen redox in a Na-rich battery, which is published on a recent issue of Chemistry of Materials.

Revealing the martensitic transformation mechanism under high pressure - Dr. Binbin Yue

JULY 18, 2019 — Variant selection is classic phenomenon during the martensitic transformations that induced by temperature. In the latest issue of PNAS, a team of scientists led by Dr. Binbin Yue from HPSTAR reported a simple variant selection effect across the pressure/stress driven martensitic transformations in Mn2O3. This work is a classic model reference to demonstrate the variant selection behavior under high pressure

Diverse stoichiometry and electronic conductivity of Na-S phases - Dr. Huiyang Gou

JULY 2, 2019 — Sodium-sulfur (Na-S) batteries are promising candidate for solid state batteries due to their high ionic conductivity, long cycle-life, high specific energy, and low material cost. A systematic and unambiguous understanding of the charging/discharging process in batteries is of great significance for the optimization of Na-S batteries. However, the fundamental structure understanding of sulfur-rich Na-S phases in charging/discharging process remains elusive.

Improved 2D perovskite from pressure - Drs. Ye Yuan and Lin Wang

JUNE 20, 2019 — New study from a team of scientists led by Dr. Lin Wang of HPSTAR applied high pressure to tune the physical properties of 2D hybride perovskite (C4H9NH3)2PbI4. They found that pressure can tremendously improve the performace of 2D perovskite — the band gap is narrowed by~54% and the carrier lifetime is 20 times longer for (C4H9NH3)2PbI4 (BA2PbI4) compared to the value at ambient conditions. This work indicates that pressure plays an effective role in tuning the optical and electronic structures of BA2PbI4, and also provides a strategy to synthesize high-performance organic–inorganic halide perovskite materials. The study is published in recent Advanced Science.

​Pressure induced drastic modulation of optical properties in DPFO - Dr. Haiyan Zheng and Junjie Guan

JUNE 12, 2019 — ​New work from a team of scientists co-led by Dr. Haiyan Zheng from HPSTAR found pressure induced tremendous modulation of the optical properties of an organic molecular crystal (DPFO). Their study shows that DPFO may have potential in the molecular switch applications of modulating photoluminescence under high pressure. Their work is published in recent Materials Chemistry Frontiers.

Pressure Induced Lattice Frustration in Spin-Orbit Mott Insulator - Dr. Yang Ding

MAY 24, 2019 — The intertwined charge, spin, orbital, and lattice degrees of freedom make the 5d compounds have exotic properties. Current interest is focused on electromagnetic interactions in these materials, whereas the important role of lattice geometry remains to be fully recognized. A group of scientists led by Dr. Yang Ding of HPSTAR, found pressure induced lattice frustration in a spin-orbit Mott insulator Sr3Ir2O7. Their work revealed the critical role of lattice frustration in determining the high-pressure phases of Sr3Ir2O7. This study is published in the npj Quantum Materials.

Halogen conversion–intercalation chemistry enables high voltage aqueous batteries - Dr. Xujie Lü

MAY 21, 2019 — An international team of scientists including Dr. Xujie Lü has developed a new halogen conversion–intercalation chemistry in graphite that produces composite electrodes with a capacity of 243 mAh g-1 at an average potential of 4.2 volts versus Li/Li+. The study is recently published in Nature.

Cation-rich compoundin Pb-Te system - Dr. Kuo Li

APRIL 23, 2019 — Scientists from HPSTAR and The University of Hong Kong combined in situ synchrotron x-ray diffraction and density functional theory and evolutionary algorithms to probe the possible new compounds in Pb-Te system. The team discovered a new cation-rich compound, Pb3Te2 in the binary system. This work is published in recent ACS Central Science.

The temperature – induced amorphous CaCO3 may help carbon cycling – Dr. Mingqiang Hou

New work from a team led by HPSTAR’s Dr. Mingqiang Hou confirmed that aragonite — a high-pressure mineral form of CaCO3, will turn to a stable amorphous phase at the subduction zone conditions. This study proposed that the amorphous calcium carbonate may help cycle carbon to the surface. Their findings are published in recent Nature Communications.

Opening up the Bandgap of Graphene - Dr. Feng Ke

​APRIL 20, 2019 — A team of scientists led by Dr. Feng Ke of HPSTAR observed the semiconducting character in compressed trilayer graphene through in-situ electrical measurements. An intrinsic bandgap of ~2.5 eV has been achieved. The realization of such wide bandgap in graphene opens new opportunities in carbon-based electronic devices. Their study was published in the recent issue of PNAS.

Diverse Phase Changes of Natural bulk Brookite - Dr. Hengzhong Zhang

APRIL 18, 2019 — New work from a team of scientists led by Dr. Hengzhong Zhang at HPSTAR probed the phase variation of natural bulk brookite under compression. They revealed how pressure medium affect the phase transition behavior of brookite. This study may be used for inferring the geological fate of brookite in nature. The work is published in ACS Earth and Space Chemistry.

​Chemistry Design Towards a Stable Sulfide-based Superionic Conductor Li4Cu8Ge3S12 - Drs. Yingqi Wang, Xujie Lü and Wenge Yang

APRIL 17, 2019 — Sulfide-based superionic conductors with high ionic conductivity have been explored as a promising candidate for solid-state Li batteries. However, their hypersensitive nature against moisture has not only made their manufacturing process complicated and costly, but also impeded their applications in novel batteries including the aqueous Li-air and Li-redox-flow designs. A sulfide-based ionic conductor Li4Cu8Ge3S12 with superior stability was developed by Drs. Yingqi Wang, Xujie Lü and Wenge Yang at HPSTAR, in collaboration with Prof. Fuqiang Huang at Peking University. The material features a rigid Cu-Ge-S open framework that increases its stability. Meanwhile, the weak bonding between Li+ and the framework promotes ionic conductivity. This study is published in Angewandte Chemie International Edition.

Pressure Makes Best Cooling - Dr. Kuo Li

MARCH 28, 2019 — New study from an international research team of scientists co-authored by Dr. Kuo Li from HPSTAR found that a class of disordered materials, called plastic crystals, exhibit record-large barocaloric effects under very weak pressure. The study reveals that the plastic crystals are the most promising materials for green cooling applications. The study is published in the recent issue of journal Nature (10.1038/s41586-019-1042-5).

Pressure made PH3 polymerize into P4H6: P4H6 may account for the superconducting - Dr. Lin Wang

MARCH 18, 2019 — ​New study from a team of scientists led by Dr. Lin Wang of HPSTAR investigated the stoichiometry and structural evolutions of phosphine (PH3) under high pressures. They found that PH3 molecules went through a step-by-step polymerization and finally dissociated to elemental phosphorus and hydrogen instead of directly dissociation as previously reported. Low temperature was found to greatly hinder the polymerization/decomposition of phosphine. The results also revealed that the decomposed product P4H6 might be responsible for the reported superconducting transition. The study is published in recent National Science Review.

Complex Phase Behaviour of Dense Chlorine- Philip Dalladay-Simpson & Ross Howie

MARCH 14, 2019 — Due to the realization of potentially exotic states, the behaviour of elemental molecular systems at high densities has long been of particular interest in the condensed matter sciences. Of the 7 elemental diatomic systems, only O2 and the heavier halogens Br2 and I2 have conclusively demonstrated electrically conductive properties in the condensed state, whilst the latter two are the only examples of diatomic molecular dissociation. In a new investigation, an international collaboration between scientists from HPSTAR, the University of Edinburgh and GeoSoilEnviroCARS (GSECARS, APS), report the behaviour of chlorine to pressures in excess of several million atmospheres. The study, which is published in Nature communications, reveals the peculiarity associated high-pressure chlorine, such as metallic modification, structural complexity and ultimately molecular dissociation.

Pressure engineering of photovoltaic perovskites - Dr. Gang Liu

​MARCH 13, 2019 — A new comprehensive study led by Dr. Gang Liu, a staff scientist at HPSTAR, reviewed the manipulation, modification, and improvement of photovoltaic perovskite materials by pressure engineering. The study focuses on the unique overlapping region between Green energy, materials, and engineering and explores whether desirable characteristics for next-generation materials-by-design are obtainable with pressure. It was recently published in MATERIALS TODAY.

Direct Reaction between Copper and Nitrogen at HP and HT– Jack Binns

MARCH 6, 2019 — Compounds of the transition metals and nitrogen have applications in many areas from ultrahard materials to explosives. To date none of the group 11 elements: copper, silver, or gold are known to form a nitride compound, MN2 despite many decades of attempts. A new study by RTH Lab of HPSTAR reports that by laser heating mixtures of the elements in diamond-anvil cells at high pressures, a direct reaction between copper and nitrogen is observed forming the new compound copper diazenide (CuN2). This study is published in The Journal of Physical Chemistry Letters.

Coating and doping make improved cathode - Dr. Shengcai Zhu

MARCH 4, 2019 — New work from Dr. Shegncai Zhu of HPSATR, collabrated with Dr. Jun Yang from Shaanxi University of Science and Technology and Prof. Yongyao Xia from Fudan University, found that overall structural modification integrating coating and gradient doping could enhance the structural stability and simultaneouly facilitate Li+ diffusion of layered Ni-rich cathode at high voltage. The work is published in recent Journal of Materials Chemistry A.

Multiple and reversible responses in viologen based MOF - Dr. Lin Wang

FEBRUARY 15, 2019 — It is challenging to mobilize as many properties as possible to one metal-organic frameworks — MOF to realize multiple responsive properties. New work from a team of scientists including Dr. Lin Wang of HPSTAR found that a newly synthesized viologen-based MOF could assembly versatile and switchable responsive properties. The work is published in recent issue of Small.

Pressure-dependence of Electrical Conductivity of Black Titania – Dr. Hengzhong Zhang

FEBRUARY 13, 2019 — New work from a research team led by Dr. Hengzhong Zhang at HPSTAR found that pressure affects the electrical conductivity of black titania via controlling the number of free electrons distributed in the conduction band, which is inversely proportional to the exponent of the bandgap that scales almost linearly with the pressure. This work is published in J. Phys. Chem. C.

A single nanowire under compression- Drs. Sudeshna Samanta & Lin Wang

FEBRUARY 4, 2019 — ​In the January 24, 2019, issue of the journal Nano Research, a team of researchers led by Dr. Sudeshna Samanta from HPSTAR reported a new progress in a single nanowire composite using high pressure techniques to unravel the electrical transportation evolution. They found strong nonlinear electrical conductivity in compressed single Pt-C nanowire which corresponds to a pressure induced quantum phenomenon.

Oxygen valence state varies at Earth's deep mantle - Drs. Jin Liu, Qingyang Hu & Ho-kwang Mao

JANUARY 15, 2019 — It is conventionally accepted that the oxygen anion has an unvarying −2 valence state for major lower mantle compositions like ferropericlase and bridgmanite. A recent study led by Dr. Ho-kwang Mao from HPSTAR found variation in the valence state of oxygen in the newly discovered Fe-O-H system under deep mantle conditions. The new finding was reported Nature Communications in January, 2019.

120 K superconductivity in Potassium doped p-quaterphenyl- Dr. Xiaojia Chen

JANUARY 10, 2019 — New work from a team of scientists led by Dr. Xiaojia Chen from HPSTAR and Haiqigng Lin of CSRC, found serials of superconducting materials in doped organic molecules. Their study has inspired a new round of research enthusiasm for scientists in the field of superconducting after the discovery of 203 kelvin in H3S. They proposed the chain link organic molecules are promising candidates for high-temperature superconductors. Their study is published on recent issue of JPCL and has been selected as the cover of the issue.

Diels-Alder Reactions Happened under High Pressure towards Graphane Structure- Drs. Yajie Wang, Haiyan Zheng & Kuo Li

JANUARY 7, 2019 — A research team led by Drs. Kuo Li and Haiyan Zheng from HPSTAR recently studied the pressure induced polymerization (PIP) of C6H6-C6F6 co-crystal, and an ordered substituted short range graphane, named as H,F-graphane was identified. They also investigated the reaction process and identified the Diels-Alder reaction is the elemental reaction for the synthesis. This provides an important reference for understanding and designing the reaction of aromatics under high pressure. The work is published on Angewandte Chemie International Edition (DOI: 10.1002/anie.201813120).

中国第一个陨石坑里的新发现 —“毛河光矿”

​DECEMBER 06. 2018 — 北京高压科学研究中心束今赋研究员与广州地球化学研究所陈鸣研究员带领的团队通过对我国的第一个陨石坑—岫岩陨石坑中岩石和矿物的冲击变质效应分析，发现了一种新矿物——一种超尖晶石结构的MgFe2O4相。这个新发现的天然矿物具有重大科学意义，为此该团队用享誉世界、国际高温高压领军人物、美藉华裔科学家毛河光院士命名。该重要高压新矿物已获得国际矿物学协会（IMA）新矿物命名及分类委员会（CNMNC）投票通过，正式获得批准命名为“Maohokite”（ 矿物编号：IMA No. 2017-047）， 中文名：”毛河光矿”。

Access into water's no man's land: discover high/low-density noncrystalline water -Dr. Chuanlong Lin

NOVEMBER 30, 2018 — Exploration of the noncrystalline H2O (namely, liquid water and glassy ice) and polyamorphous transition in so-called water_sqlquote_s no man_sqlquote_s land (~150 K-232 K), have been hindered by the thermodynamically driven crystalline-crystalline transitions and rapid crystallization. Dr. Chuanlong Lin and colleagues overcome this challenge by using a newly developed technique of rapid loading (unloading) integrated with fast synchrotron x-ray diffraction measurements. They have discovered the high-density noncrystalline water and the transformation to low-density liquid water. The work is published on recent Physical Review Letters.

Pressure-driven p-n switch in CuFeS2 – Drs. Ting Wen, Yonggang Wang & Wenge Yang

NOVEMBER 29, 2018 — A new work from a group of scientists co-led by Drs. Ting Wen, Wenge Yang and Yonggang Wang of HPSTAR reported a pressure-driven reversible switching between n- and p-type conduction in chalcopyrite CuFeS2. The successful realization of an abrupt conduction type switch in transition metal semiconductors under high pressure paves the way to novel pressure-responsive switching devices. This work is published online in recent J. Am. Chem. Soc.

98% of the Universe as Unreactive as Ever - Dr. Ross Howie

NOVEMBER 13, 2018 — Extreme conditions are very common in the universe, from the cold vacuum of deep space to the elevated temperatures and pressures within planets. The gas-giant planets, Jupiter and Saturn, consist primarily of hydrogen and helium, whilst the nitrogen-hydrogen bonded compound ammonia, is abundant on Saturns icy moons, Titan and Enceladus.

Elusive Nitrogen Phase Exhibits Unexpected Complexity – Dr. Ross Howie

NOVEMBER 12, 2018 — Although one might think that nitrogen, the primary constituent of the air which we breathe, is simple, it exhibits rich polymorphism across a wide range of extreme pressures and temperatures. Here a research team including HPSTAR members Jack Binns, Ross Howie and Eugene Gregoryanz, were able to experimentally resolve one of the most elusive forms of this model system, the dense solid iota-phase, that can only be accessed through a high temperature synthesis route. This work is published in Nature Communications (DOI: 10.1038/s41467-018-07074-4).

Pressure makes better Li-ion battery- Dr. Lin Wang

NOVEMBER 9, 2018 — New work from a team of scientists led by Dr. Lin Wang of HPSATR found that high pressure turned so called zero-strain anode Li-ion battery (Li4Ti5O12 or LTO) to amorphous and made its electrical conductivity largely improved. This study offers a new method for improving the conductivity of lithium-ion batteries using high-pressure technique. The work is published in recent National Science Review.

The first nickel polyhydride Ni2H3 - Dr. Jack Binns

OCTOBER 11, 2018 — Combining high pressures and temperatures can lead to the formation of unusual new compounds. A new study by a group of HPSTAR scientists applies this method to the search for new transition metal hydrides, finding the first nickel polyhydride Ni2H3. This study was published as a Rapid Communication in Physical Review B.

Unexpected semi-metallic BiS2 at HP and HT - Dr. Lin Wang

SEPTEMBER 27, 2018 — New work from a team of scientists led by Dr. Ling Wang from HPSTAR and Prof. Yanming Ma of Jinlin University predicted new compounds in the Bi-S system and experimentally synthesized the predicted BiS2 compound under high pressure and temperature conditions. Their further electronic calculations indicate that this new found BiS2 is a a promising semi-metallic material. This work is published in recent JPCL.

Synthesis of GeSe with robust ferroelectricity under extreme conditions - Dr. Kuo Li & Dexiang Gao

SEPTEMBER 10, 2018 — By combing with the high pressure and high temperature synthesis as well as density functional theory and evolutionary algorithms calculation, scientists from HPSTAR and The University of Hong Kong explored the pressure-induced phase transitions of GeSe systemically. Two novel phases (R3m and Fm3m) are discovered which show robust ferroelectricity and a 3D topological crystalline insulator, respectively. The R3m phase was synthesized by compressing the a-GeSe under high temperature. This research greatly enrichs our knowledge of IV-VI compounds. The results were published on NPG Asia Materials .

Pressure induced metal to semiconductor transition in 2D electride - Dr. Huiyang Gou

SEPTEMBER 4, 2018 — New work from a team led by Dr. Huiyang Gou from HPSTAR reveals the metal-to-semiconductor transition in compressed Ca2N a two-dimensional (2D) electride as found in sodium. This work is published in Advanced Science.

High-Pressure effects on a honeycomb iridate - Drs. Yang Ding

AUGUST 17, 2018 — New work from a team of scientists including Dr. Yang Ding from HPSTAR confirm that Kitaev-quantum-spin candidate material, a-Li2IrO3 will lose its exotic quantum state under compression instead of becoming predicted Kitaev spin liquid from multiple in-situ characterizations combined with theoretical calculations. This work is published in recent NPJ Quantum Materials.

Reaching metastability via isothermal pressure pathways – Dr. Gang Liu

​JULY 26, 2018 — The phenomenon of metastability, in which a system is in a state that is stable but not at the lowest energy, is obtained most-commonly through fast cooling from high temperature. Now, a team of scientists co-led by Dr. Gang Liu from HPSTAR report attainable metastable states in 2D solar perovskites from compression-decompression paths. The metastable phases show much superior optical properties.

Thermoelectricity revisits silicon - Dr. Duckyoung Kim

JULY 19, 2018 — New report from a team of scientists led by Dr. Duck Young Kim from HPSTAR, found that their recently synthesized silicon allotrope, namely Si24, with nanoscale porous structure showed extremely favorable thermoelectric properties with slightly doping, comparing with normal silicon. This work is published in recent Nano Letters.

Microscale inhomogeneity in Bi-2212 and the correlation with superconductivity - Dr. Yang Ding

JULY 14, 2018 — New work from a group of scientists led by Dr. Yang Ding of HPSTAR, provided the first experimental evidence of lattice inhomogeneity in high-temperature superconductors and found that the structural inhomogeneity correlates well with superconductivity in single-crystal Bi-2212—bismuth-based cuprate (Bi2Sr2CaCu2O8+δ) at high pressure. This study is published in the Journal of Physical Chemistry Letters.

Structure and Metallicity of Phase V of Hydrogen - Drs. Philip Dalladay-Simpson and Ross T. Howie

JUNE 18, 2018 — A new study from a team of scientists, which comprised of HPSTAR’s Philip Dalladay-Simpson and Ross T. Howie, proposed a promising candidate crystal structure for their recently discovered phase of hydrogen, phase V. Most poignantly the work, which was recently published Physical Review Letters, provides further evidence that phase V is indeed a stepping stone towards hydrogen’s elusive metallic form.

Enhanced reactivity of lithium and copper at high pressure - Dr. Jack Binns

JUNE 6, 2018 — High pressure can profoundly affect electronic structure and reactivity, creating compounds between elements that do not react at ambient conditions. Lithium is known to react with gold and silver, however no copper compounds are known to date. New study by a group of HPSTAR scientists reports that by compressing mixtures of the elements in diamond-anvil cells, compounds of lithium and copper have been synthesized for the first time. This study is published in the Journal of Physical Chemistry Letters.

Observation of superconductivity in Fe honeycomb lattice - Drs. Wenge Yang and Yonggang Wang

MAY 16, 2018 — After continuous insistence on the pressure-driven spin-crossover in transition metal chalcogenides, a group of scientists co-led by Dr. Wenge Yang and Dr. Yonggang Wang of HPSTAR, firstly observed the emergence of superconductivity in Fe-based honeycomb lattice under compression. Before this, all the iron-based high-Tc superconductors structurally adopt FeSe-type square Fe lattice. The discovery provides a state-of-art demonstration for the pursuit of transition metal based superconductors under extreme conditions. This work is published by Nature Communications​.

Structure evolution and the relationship between high-pressure phases of VO2 – Dr. Haozhe Liu

APRIL 28, 2018 — Pressure-induced phase transition always involves symmetry and coordination change in a crystal. While researchers most focus on symmetry change instead of considering its coordination or local bonding varying when a crystal structure changed. A team of scientists led by Dr. Haozhe Liu of HPSTAR find a general coordination increase in VO2 phase transitions and state that this structure-evolution rule may commonly exist in other dioxides. This work is published on JPCL.

High-pressure effects on the iron-free layered pnictide, BaPd2As2 – and pulsed field experiment in Ba2Ti2Fe2As2O4 up to 60T done in Wuhan - Dr. Mahmoud Abdel-Hafiez

APRIL19, 2018 — The compound BaPd2As2 represents the end member of the Pd-doped series and exists in the form of two types of crystal structures: ThCr2Si2-structure type (I4/mmm) and CeMg2Si2-structure type (P4/mmm). The former structure has bulk superconductivity, while in the latter structure only filamentary superconductivity was observed below 2 K. This shows that the crystal structure has a predominant effect on the superconducting properties of these systems.

High pressure synthesis and stability of cobalt hydrides - Mengnan Wang

APRIL 18, 2018 — The synthesis and properties of hydrogen-bearing compounds is an intensively studied area of physics and chemistry, mainly driven by hydrogen-storage applications. High pressure and high temperature have been an effective route to synthesis hydrides with extremely high hydrogen content. A new study by RTH lab, reports the discovery of new cobalt compounds, CoH and CoH2, with high hydrogen content of 3.3 wt% and a volumetric hydrogen density of 214g/L. This study is published in J. Chem. Phys​.

Mantle minerals offer clues to deep Earth's composition - Dr. Yonggang Wang

MARCH 31, 2018 — Through high-pressure experiment studies on bridgmanite, the most abundant mineral in the Earth’s mantle, a group of scientists include Dr. Yonggang Wang of HPSTAR, determined the influence of spin state and valence state of Fe on bridgmanite density, bulk sound velocity, and electrical conductivity. Based on their high-pressure experimental data on Fe3+-only bridgmanite together with previous results on Fe2+-domain bridgmanite, they found that neither valence state nor spin state of Fe in bridgmanite would cause significant seismic signature in the mantle. The discovery is published by Nature Communications​.

Solids, liquids, and gases under high pressure - Dr. Ho-Kwang Mao

MARCH 20, 2018 — Pressure has long been recognized as a fundamental thermodynamic variable. It drastically alters physical and chemical properties of materials. A review on Reviews of Modern Physics from HPSTAR researchers led by Dr. Ho-Kwang, provides an in-depth review of how pressure drastically change our world and the key developments that have led to surprising high-pressure physics and chemistry and created novel materials along with the current status and future perspectives of multidisciplinary advancement in high-pressure chemistry, geoscience, astrophysics, and materials applications.

Natural diamond formation by self-redox of barbonate - Drs. Jinfu Shu and Ho-Kwang Mao

MARCH 15, 2018 — Intensive research on deep-Earth diamonds over the past half century has shown that the formation of most natural diamonds are via redox reactions involving carbon-bearing phase fluid or melt with external reductants. New study from a team of scientists co-led by HPSTAR director Dr. Ho-Kwang Mao found natural diamond could also form by a self-redox process without other reductant. This work is published in recent PNAS. Their study suggests that diamond could be a dominant host of carbon in the Earth’s lower mantle.

Discovery of a hexagonal hydrous phase in the deep lower mantle - Dr. Li Zhang

MARCH 7, 2018 — The Earth’s lower mantle comprises >55% by volume of our planet, extending from 670 to 2900 kilometers in depth. The lower mantle is potentially the most massive water reservoir in our planet, which largely depends on availability of hydrous minerals which can store and transport water down to the deep lower mantle. Through high-pressure-temperature experiments in a laser-heated diamond anvil cell at 107–136 GPa and 2,400 K, a research team at HPSTAR discovered an ultradense hydrous phase in (Fe0.8Al0.2)OOH with a previously unknown hexagonal lattice. The team includes Li Zhang, Hongsheng Yuan, Ho-kwang Mao of HPSTAR, and Yue Meng of High Pressure Collaborative Access Team (HPCAT) of the Advanced Photon Source (APS). The discovery is reported in Proceeding of the National Academic of Sciences, USA.

Novel 2D silicon with flat surface - Dr. Duckyoung Kim

FEBURARY 28, 2018 — New work from a team of scientists including Dr. Duckyoung Kim from HPSTAR have predicted a serials of novel layered silicon crystals with stable flat surface structure and versatile electronic structures. They proposed that their study will help the development of silicon-based two dimensional electronic technology. The study is published in recent 2D Materials.

How diamond anvil cell works up to 4 Mbar - Dr. Bing Li

FEBRUARY 11, 2018 — Diamond anvil cell (DAC) has been used for almost 60 years to simulate extreme pressure environments, it holds the static pressure record generated in laboratories on the earth. Although some studies have demonstrated techniques to generate 4 million atmosphere pressures (400 GPa) – the generally accepted limit pressure of a conventional DAC, yet few have examined how the DAC behaves in this pressure region. Using submicron synchrotron x-ray beam, a group of scientists led by Ho-kwang Mao, director of HPSTAR (the Center of High Pressure Science and Technology Advanced Research, China) have studied the loading behavior of DAC up to 400 GPa. A universal s-shape loading behavior and unavoidable cupping were found for the conventional DAC experiments.

Formation of H2-rich iodine-hydrogen compounds at high pressure - Dr. Ross Howie

FEBRUARY 5, 2018 — Hydrogen-rich compounds have attracted attention because of their potential application in hydrogen storage and for high-Tc superconductivity. High-pressure methods have proven very effective in the search for new materials with high hydrogen contents. A new study led by Dr Jack Binns, a postdoctoral researcher in the group of Dr Ross Howie, reports the discovery of a new high-H2 content compound with an unprecedented formula of HI(H2)13. A combination of X-ray diffraction, Raman spectroscopy, and molecular dynamics were used to determine the structure and explain the extraordinary stability of this compound with increasing pressure. This study is published in Physical Review B.

Pressure induced superconductivity in MoS2 – Dr. Jinglong Zhu

JANUARY 31, 2018 — Superconductivity is a physical state occurring in certain materials, called superconductors, in which electrical resistance disappears completely when coo​led below a characteristic critical temperature. This phenomenon can be induced under chemical and high external pressure conditions. New work from a team including Dr. Jinglong Zhu of HPSTAR found superconducting MoS2 under extreme pressure conditions. This work is published by Physical Review Letters.

​Giant oxygen reservoirs near the Earth's core – Seek and find - Dr. Ho-Kwang Mao

NOVEMBER 23, 2017 — Free oxygen in the air that gives life to our living planet cannot be taken for granted. In fact, during the first half of the Earth’s 4.6 billion year history, oxygen was absent in the atmosphere. Only 2.4 billion years ago at the Great Oxidation Event (GOE), oxygen appeared suddenly, thus enabling the aerobic life like us to thrive and evolve. In seeking for possible source of the oxygen rise, superoxidized iron from great depth is a potential candidate.

Synthesis and stability of hydrogen selenide compounds at high pressure - Dr. Ross Howie

NOVEMBER 20, 2017 — The observation of high-temperature superconductivity in hydride sulfide (H2S) at high pressures has generated considerable interest in compressed hydrogen-rich compounds. The heavier hydrogen chalcogenides (i.e., H2Se and H2Te) are predicted to also exhibit high Tc superconductivity, however up until now remained experimentally unexplored. A new study led by Dr. Ross Howie of HPSTAR investigated the synthesis and stability of H2Se at high pressure and finds remarkable similarities with H2S. This study is published in J. Chem. Phys.

Water modulation of photo- and piezochromism in viologen - Dr. Lin Wang

NOVEMBER 3, 2017 — It is proposed that the lattice water does not act as an electron donor but serves to change the electro transfer energetic through its unique polarity and hydrogen bonding capability. New study led by Dr. Lin Wang of HPSTAR and Prof. Enqi Gao of East China Normal University found that the higher the water content in the lattice, the less sensitively the compounds respond to light and pressure in a series of different viologen pseudopolymorphic solids. The story is reported in the recent issue of JPCL​.

Complex screw dislocation core in zeolite MTW - Dr. Shengcai Zhu

OCTOBER 30, 2017 — A group of scientists co-led by Dr. Shengcai Zhu of HPSTAR, investigated the evolution of hyper structure and screw dislocation for the framework material zeolite MTW, a useful industrial solid acid catalyst. They revealed that the complex screw dislocation core in zeolite MTW was composed by different crystal domains with different stacking vector. Their findings are published by recent issue of Angewandte Chemie International Edition (DOI:10.1002/anie.201704499).

First high pressure study on 2D hybrid perovskites - Dr. Gang Liu

OCTOBER 19, 2017— New work led by HPSTAR researcher, Dr. Gang Liu experimentally convinced a first example of pressure-improved 2D hybrid perovskites and proposed that pressure treatments might offer a useful route to yield near-ideal single junction performance in the 2D hybrid perovskites. The discoveries are published by ACS Energy Letters.

How pressure change the world of perovskite solar cells - Dr. Xujie Lü

SEPTEMBER 29, 2017 — Pressure, as a fundamental thermodynamic parameter that can tailor physical and chemical properties of functional materials, has recently been used in tuning structures and properties of organic-inorganic hybrid perovskites. In recent issue of Chemical Science, a team of scientists led by Dr. Xujie Lü of HPSTAR gave a perspective of how pressure make changes in the hybrid perovskites.

Fate of water into the earth - Dr. Ho-Kwang Mao

SEPTEMBER 11, 2017 — From a geoscientist_sqlquote_s view, the earth is made up of a giant iron core, covered by a thick layer of silicate mantle and a thin coating of crustal rocks. Water concentrates in oceans on Earth’s surface. A portion of water reacts with rocks and forms the so-called hydrous minerals that can transport deep into the mantle. Once they reach the bottom of the mantle, naturally we’ll ask the question: what will happen when water meets the iron core? A team led by Dr. Ho-Kwang Mao, director of HPSTAR published their answer to this question in the latest issue of National Science Review (DOI: 10.1093/nsr/nwx109).

Pressure induced abnormal insulating state in LixCoO2 - Cong Xu

SEPTEMBER 8, 2017 — New work led by HPSTAR graduate student, Cong Xu found abnormal semiconductor to insulator transition in cathode material, Li0.9CoO2 under pressure. The findings uncovered by the comprehensive high pressure investiations provide deep insights into the complex relationship of the crystal structure and electronic performance in this important cathode material, which may be used for guiding the future lithium metal oxides battery industry for better performane. The discoveries are published by the Journal of Materials Chemistry A (DOI: 10.1039/C7TA06084J).

Two superconducting domes in FeS - Fengliang Liu

SEPTEMBER 1, 2017 — A team co-led by HPSTAR PhD student Fengliang Liu, investigated the evolution of superconductivity and structure with pressure for the new superconductor FeS (Tc ≈ 4.5 K), a sulfide counterpart of FeSe. They observed two superconducting domes in FeS under compression with 30% enhancement in maximum Tc in the second dome. Their discoveries are published by NPJ Quantum Materials (DOI:10.1038/s41535-017-0050-7).

Pressure-induced irreversible conductivity enhancement in lithium acetylide - Drs. Lijuan Wang and Xiao Dong

AUGUST 27, 2017— Lithium acetylide, as a widely used electrode material for Li-ion battery has the highest theoretical capacity while with low conductivity for applications. New work from a HPSTAR team increased the conductivity of Lithium acetylide by 9 orders of magnitude in the use of high pressure method. And this pressure-enhanced conductivity could be kept to ambient conditions. Their discoveries are published by the Journal of Physical Chemistry Letters (DOI: 10.1021/acs.jpclett.7b01779).

A degassing mechanism for deep hydrous mineral - Dr. Qingyang Hu

​AUGUST 23, 2017 — Thanks to the symmetric O-H-O bonding, a certain class of hydrous minerals is recently discovered to survive in the high-pressure high-temperature condition that mimics the deep lower mantle. The composition FeO2H, named goethite when they are found on Earth surface, is one of such hydrous minerals. It forms symmetric O-H-O framework at high-pressure hence features higher dehydration temperature. However, at even deeper depth scientists suggest new profound chemistry related to FeO2H. New works from a team including HPSTAR’s Shengcai Zhu, Qingyang Hu, Ho-kwang Mao, Hongwei Sheng and collaborator Wendy Mao from Stanford University has identified that such symmetric network will break above around 750,000 atmosphere and 1400 °C. Their results were published in the Journal of American Chemical Society (DOI: 10.1021/jacs.7b06528).

Diamond can be amorphous: from scenario to reality - Dr. Zhidan Zeng

AUGUST 22, 2017 — A team led by HPSTAR scientist, Dr. Zhidan Zeng synthesizes a new form of carbon —“amorphous diamond”—under high pressure and temperature (HPHT). This bulk amorphous diamond obtained under HPHT can be maintained to ambient conditions for potential applications, realizing possible the hardest amorphous (glass) material ever discovered. This work is recently published as an article by Nature Communications (Synthesis of quenchable amorphous diamond. Nature Communications, 2017).

High-Pressure Behavior of Hydrogen and Deuterium at Low Temperatures - Drs. Ross Howie and Xiaojia Chen

AUGUST 17, 2017 — New work by HPSTAR_sqlquote_s Ross Howie and Xiao-Jia Chen, in collaboration with the ISSP Chinese Academy of Sciences, presents the first high-pressure experimental study of hydrogen that was completely conducted within China. The authors present in situ high-pressure low-temperature high-quality Raman data for hydrogen and deuterium where they demonstrate the presence of a novel phase, phase II’, unique to deuterium. This work is published Physical Review Letters (DOI: 10.1103/PhysRevLett.119.065301).

A new graphitic carbon nitride made under pressure - Dr. Huiyang Gou

AUGUST 14, 2017 — Nitrogen-bearing, carbon-rich materials are known to have multiple functionalities and diverse applications. Graphitic carbon nitride (g-C3N4) is the most common C-N phase studied, but several other phases with varying compositions and properties have been predicted. A group of scientists led by Huiyang Gou of HPSTAR and Timothy Strobel of Geophysical lab performed high-pressure experiments on linear dicyanoacetylene (C4N2) using a diamond anvil cell, in which a pressure-induced reaction process of was uncovered. Discrete linear C4N2 molecules were found to polymerize into a disordered extended network without significant change to the bulk composition. The results were published in Chemistry of Materials.

LSO — Ideal optical pressure sensor - Dr. Wenge Yang

JULY 11, 2017 — A material with good structural stability, chemical durability, and radiation tolerance under extreme conditions is necessary and long challenge for developing new pressure sensors. New work co-led by HPSTAR scientist, Dr. Wenge Yang found novel visble photoluminescence in pyrochlore La2Sn2O7 induced by pressure. This unexpected reversible photoluminescence suggests that La2Sn2O7 might be an ideal optical pressure-sensor under extreme conditions.

Enhanced Superconductivity in Pressure Quench in In2Se3 – Dr. Feng Ke

​JULY 11, 2017— Pressure induced superconductivity has been realized in several systems, while the superconductivity will disappear with pressure quench. So how to preserve the pressure-induced superconductivity remains a problem to be solved. New research from HPSTAR revealed that enhanced superconductivity happened in In2Se3 during pressure quench. This opens up a possible route to preserve the high-temperature superconductors induced by compression to low and even ambient pressure. Their work is published by Advanced Materials.

New form of carbon that's hard as a rock, yet elastic, like rubber -Drs. Jinfu Shu, and Ho-Kwang “Dave” Mao

​JUNE 9, 2017—Carbon is an element of seemingly infinite possibilities. This is because the configuration of its electrons allows for numerous self-bonding combinations that give rise to a range of materials with varying properties. For example, transparent, superhard diamonds, and opaque graphite, which is used for both pencils and industrial lubricant, are comprised solely of carbon. A international team including HPSTAR scientists Drs. Jinfu Shu, and Ho-kwang “Dave” Mao, have developed a form of ultrastrong, lightweight carbon that is also elastic and electrically conductive. A material with such a unique combination of properties could serve a wide variety of applications from aerospace engineering to military armor.

High-Entropy Alloy: changing faces under high pressure - Dr. Qiaoshi Zeng

JUNE 2, 2017 — New study co-led by a HPSTAR staff scientist, Dr. Qiaoshi “Charles” Zeng revealed irreversible polymorphic phase transitions between the fcc and hcp structures in a prototype high-entropy alloy CoCrFeMnNi using in situ high pressure and high temperature x-ray diffraction techniques. Their discovery was just published in Nature Communications (DOI:10.1038/ncomms15687) on June 1st. These results shed new light on the thermodynamics and kinetics of complex HEA systems and also opens a new avenue towards tuning HEAs’ properties via polymorphic structural transitions for applications.

The composite material makes the ultrafast lithium ion capacitors - Dr. Huiyang Gou

APRIL 14, 2017 —The rapidly growing energy demand requires the development of advanced electrical energy storage technology. New work from a team including Dr. Huiyang Gou at HPSTAR and Dr. Gongkai Wang from Hebei University of Technology and Prof. Jie Lian from RPI published in Nano Energy show that the composite materials of nanosized Li4Ti5O12 (LTO) and graphene nanosheets can have excellent reversible capacity, rate capability, and cyclic stability as anode materials for lithium ion capacitors.

A Possible Route from C2H2 to Graphane - Drs. Kuo Li and Haiyan Zheng

MAY 3, 2017 —
Scientists from HPSTAR, co-led by Drs. Kuo Li and Haiyan Zheng, have quantitatively explained the reaction route of polymerization of C2H2 under extreme condition by neutron diffraction and theoretical calculation. They discovered that under high pressure, acetylene molecules react along a specific crystallographic direction, which leads to the cis-polyacetylene. Following this route, the scientist discovered a potential method to synthesize graphane. By combing multiple methods, a layered polycyclic polymer was synthesized and identified as an intermediate between polyacetylene and graphane. This research provides a novel method of synthesizing carbon materialand the results are published in Angew. Chem. Int. Ed.(DOI: 10.1002/anie.201702685).

Strong coupling between Weyl fermions and phonons in TaAs - Dr. Bing Xu

APRIL 5, 2017 —
Scientists from HPSTAR and IOP-CAS, in collaboration with Dr. Rohit Prasankumar’s group at LANL, studied the temperature evolution of electronic and phonon properties of the Weyl semimetal TaAs using infrared spectroscopy. They found explicit evidence for strong coupling between an infrared-active A1 phonon and Weyl fermions in TaAs. The study is published in Nature Communications (DOI: 10.1038/ncomms14933).

Unexpected stoichiometry in Sn-Se system - Dr. Kuo Li

MARCH 30, 2017 —
Scientists from HPSTAR and The University of Hong Kong combined in situ synchrotron x-ray diffraction and density functional theory and evolutionary algorithms to examine the high-pressure structural behavior of Sn-Se system. The team observed a new compound with an unexpected stoichiometry in the Sn-Se binary system. The research is published in the March 28th edition of Physical Review Letters.

Pressure-tuned multiferroic KBiFe2O5 - Dr. Ganghua Zhang

MARCH 16, 2017 — New study from a team of HPSTAR scientists, led by Drs. Ganghua Zhang and Wenge Yang, find that pressure can simultaneously enhance ferroelectric and photoelectric properties of multiferroic KBiFe2O5. These findings may open a new avenue to discovering and designing optimal ferroelectric compounds for solar energy applications. The work was highlighted on the Advanced Electronic Materials cover.

Record pressure squeezes stability of Ar(H2)2- Dr. Cheng Ji

MARCH 15, 2017— Hydrogen-rich materials have been predicted to be promoters for the metallization of hydrogen. A group of scientists led by HPSTAR director, Dr. Ho-kwang Mao has studied Ar(H2)2, a hydrogen-rich material formed by Argon (Ar) and Hydrogen (H2), to 358 gigapascals — almost the pressure in the inner core of the Earth, by combining experimental and theoretical methods. Contrary to the previous thought, it was observed that Ar damps the intermolecular interactions between H2 molecules, an effect as ‘negative’ chemical pressure which postpones metallization. The results were published in Proceeding of the National Academic of Sciences, USA.

Smaller nanocrystals may not rotate more after all - Dr. Bin Chen

MARCH 2, 2017 — For more than 60 years, the conventional belief has been that smaller grains of materials rotate more under stress due to the motion of grain boundary (GB) dislocations. Under the guidance of Dr. Bin Chen of the Center for High Pressure Science & Technology Advanced Research (HPSTAR), Xiaoling Zhou, a Ph.D. student of HPSTAR, and co-workers observed that nanocrystals of a critical grain size rotate more than any other grain size. The results were published today in the journal Physical Review Letters: “Reversal in the Size Dependence of Grain Rotation”.

Helium chemistry under high pressure - Dr. Xiao Dong

FEBRUARY 07, 2017 — Although helium is the second (after hydrogen) most abundant element in the universe, it doesn_sqlquote_t play well with others. Now, an international team of researchers, including HPSTAR scientist, Dr. Dongxiao has predicted two stable helium compounds — Na2He and Na2He O. The scientists experimentally confirmed and theoretically explained the stability of Na2He. This work published by Nature Chemistry (DOI:10.1038/nchem.2716), could hold clues about the chemistry occurring inside gas giant planets and possibly even stars, where helium is a major element.

Freeing hydrogen in Earth's lower mantle - Dr. Ho-Kwang Mao

FEBURARY 04, 2017 — In Earth interior, water (H2O) plays an important role in rock physics but geoscientists rarely treat water in its decomposable forms, like hydrogen plus oxygen. However, new work from a team led by HPSTAR director, Dave Mao, has identified the hydrogen can escape from the water under lower mantle conditions. Their results were published in Proceeding of the National Academic Science, U.S.A.

Exotic two dimensional silica – Dr. Xiao Dong

JANUARY 31, 2017 — Using computer modeling, scientists from HPSTAR and Tongji University have found out three new forms of 2D-silica with exotic mechanical and electrical properties — large negative Poisson_sqlquote_s ratios and widest electric bandgap among all reported 2D materials . They detailed their work in the latest issue of the journal Nano Letters (DOI: 10.1021/acs.nanolett.6b03921).

New Stories for Viologen Materials - Dr. Lin Wang

JANUARY. 23, 2017 — Viologen materials have been well known for electrochromism and photochromism from electro and photo stimulus. New work from a team led by Prof. Enqing Gao of East China Normal University and Dr. Lin Wang from hpstar found piezochromis in viologen compounds. This is not only a new chromic phenomena for viologen compounds but also represents the first example of organic mechanochromism and hydrochromism associated with radical formation via electron transfer, proposed in the paper published in the journal Chemical Science (DOI: 10.1039/C6SC04579K).

Exotic ST12-Gemanium - Dr. Duckyoung Kim

JANUARY. 03, 2017 —Scientists including Dr. Duckyoung Kim from HPSTAR combined experimental and theoretical methods to probe the exotic properties of one special form-ST12-Ge of the element germanium. The results solve the long-standing debate on the optical and electronic properties of semiconducting Ge and suggest ST12-Ge to be a better material for infrared detection and imaging instead of single-junction solar absorbing.

Origin of ultrahigh piezoelectricity in relaxor-ferroelectrics - Dr. Gang Liu

DECEMBER 21, 2016 — Over last 60 years, efforts to enhance piezoelectricity generally resort to tuning the long-range ferroelectric phase transition. In the work published in the recent issue of Nature Communications (doi:10.1038/ncomms13807), the researchers revealed that small amount of nanoscale local inhomogeneity may dramatically improve the piezoelectric responses (50-80%) of a ferroelectric crystal.

Pressure realized bandgap requirement by Shockley-Queisser limit in FAPbI3 - Dr. Gang Liu

DECEMBER 6, 2016 — For the first time, scientists have reached the Shockley-Queisser theory optimized bandgap for single-junction solar cells in lead-based perovskites. A new study led by HPSTAR scientist Dr. Gang Liu, report an unprecedentedly tuned bandgap of the Shockley–Queisser limit and double-prolonged carrier lifetime in formamidinium lead triiodide (HC(NH2)2PbI3) in the latest issue of Advanced Functional Materials (DOI: 10.1002/adfm.201604208).

Cooperative spin-crossover under pressure - Dr. Wenge Yang

DECEMBER 5, 2016 — Spin crossover (SCO), an intriguing phenomenon that magnetic ions can switch between high-spin (HS) and low-spin (LS) states in response to light irradiation or temperature, is mostly observed as a spectacular molecular magnetism in 3d4-3d7 metal complexes. In particular, SCO materials can be multifunctional when a light- or temperature-induced SCO occurs along with structural and/or electrical alterations, and thus hold great promise for applications such as memory, display and sensor. Contrastively, pressure-induced SCO often occurs as a progressive process due to the gradual effect of pressure on the inter-atomic distance and bandgap. This greatly hinders harnessing pressure-induced SCO for potential applications in sensors or memory devices. A joint team of researchers co-led by Dr. Wenge Yang from HPSTAR reported their breakthrough in pursuing "cooperative" pressure-driven SCO in J. Am. Chem. Soc. (DOI: 10.1021/jacs.6b10225). An abrupt pressure-driven SCO accompanying with large lattice collapses and semiconductor-to-metal transitions was achieved in two-dimensional honeycomb lattices, MnPS3 and MnPSe3, for the first time. The work opens a new avenue for the exploration of pressure-responsive multifunctional materials.

Possible coexistence of superconductivity and superhardnessin BeB6- Dr. Huiyang Gou

NOVEMBER 21, 2016 — New work co-led by HPSTAR scientist, Dr. Huiyang Gou, theoretically predicts the structural and physical properties of beryllium hexaboride (BeB6) at ambient and high pressures. The ambient phase of BeB6 shows a Vicker_sqlquote_s hardness comparable to that of γ-B/cBN and coexists with superconductivity, which is unusual and exciting. This study provides new insights into the bonding mechanism for design and synthesis of novel functional materials

Formation of Xenon-Nitrogen Compounds at High Pressure - Dr. Ross Howie

OCTOBER 17, 2016 — A group led by HPSTAR scientist Dr Ross Howie and including Dr Jack Binns (RTH Lab) and Dr Phillip Dalladay-Simpson (CEP), in collaboration with researchers from CSEC (Edinburgh, UK) used high pressures to explore the possibility of forcing two of the more unreactive elements of the periodic table, xenon and nitrogen, to react. Joint investigation by X-ray diffraction and Raman spectroscopy showed the formation of a novel van der Waals compound at pressures as low as 5 GPa. After transformation to a lower symmetry phase this material, Xe(N2)2, remains remarkably stable up to at least 180 GPa and temperatures of 2000 K. This study is published in the journal Scientific Reports (doi:10.1038/srep34896).

FeSe: What is the consensus on its gap structure? - Dr. Mahmoud Abdel-Hafiez

OCTOBER 9, 2016 — By the in situ angle resolved photoemission spectroscopy (ARPES) measurements on an excellent quality of FeSe single crystal, an international joint team co-led by Dr. Mahmoud Abdel-Hafiez from HPSTAR, realized that the superconducting gap shows a pronounced twofold anisotropy around the elliptical hole pocket near Z (0, 0, π), with gap minima at the end points of its major axis. The study is published in the journal Phys. Rev. Lett. (DOI: 10.1103/PhysRevLett.117.157003 ).

New Weyl semimetal phase in TaAs– Dr. Wenge Yang

SEPTEMBER 30, 2016 — A joint team co-led by HPSTAR scientist Wenge Yang studied the envolution of electronic and structural properties of Weyl semimetal TaAs using multiple methods. They found a pressure-induced new Weyl semimetallic phase with isoenergetic 12 Weyl nodes in TaAs. The study is published in the journal Physical Reviews Letters (DOI:https://doi.org/10.1103/PhysRevLett.117.146402).

Deformation Behavior across the Zircon-Scheelite Phase Transition - Drs. Fang Hong & Bin Chen

SEPTEMBER 23, 2016 — Dynamic flow and stress information may be reconstructed from materials’ preferred orientations. Recent experimental work from a team of HPSTAR scientists led by Drs. Fang Hong and Bin Chen, show that the high-pressure mineral Scheelite can inherit texture from its lower-pressure Zircon phase, suggesting new ways of interpreting flow in the upper mantle and transition zone. The study is published in the journal Phys. Rev. Lett. (DOI: 10.1103/PhysRevLett.117.135701).

More stable perovskite solar cell treated by pressure - Drs. Qiangyang Hu and Wenge Yang

SEPTEMBER 9, 2016 — As part of a team co-led by HPSTAR scientists Dr. Qingyang Hu and Dr. Wenge Yang recently conducted the first comparative study of a lead-free tin halide perovskite, CH3NH3SnI3, before and after high-pressure treatment up to 30 GPa at HPCAT. It became more stable after high-pressure treatment, with a three-fold increase in electrical conductivity and enhanced light absorption.

Pressure induced Polymerizationand metaliztion of CaC2 - Drs. Haiyan Zheng & Kuo Li

AUGUST 30, 2016 — Transformation between different types of carbon–carbon bonding in carbides often results in dramatic changes of physical and chemical properties. New work from a team led by scientists from HPSTAR, Drs. Haiyan Zheng and Kuo Li has given a systematical investigation on CaC2 under external pressure from multiple techniques and found linear acetylide anions will polymerize into cyclic ribbons structure, accompanying with more than 107 folds enhancement in the conductivity. The journal Chemical Science​ has published an article featuring the results of the study (DOI: 10.1039/c6sc02830f).

C-H bond activated by high pressure in Acetonitrile - Drs. Haiyan Zheng and Kuo Li

AUGUST 29, 2016 — Acetonitrile (CH3CN) is the simplest and one of the most stable nitriles. It is well known that the reaction usually occur on the CN triple bond rather than the inert C-H bond. New work from a team of HPSTAR scientists co-led by Drs. Haiyan Zheng and Kuo Li found that the C-H bond can be activated by the cyano group under high pressure. The hydrogen atom transfers from the CH3 to CN along the CH...N hydrogen bond which produces an amino group and initiates the polymerization. This stories is published in Angew. Chem Int. Ed. (doi: 10.1002/anie.201606198).

Pressure-driven cooperative spin and lattice collapses in Mn(II) Chalcogenides - Dr. Wenge Yang

AUGUST 2, 2016 — Recently, giant pressure-driven volume collapse (> 20%), a rarely reported phenomenon in condensed matter, was observed in MnS2 and MnS. The intriguing behavior was considered to be associated with the pressure-driven high-spin to low-spin transition of Mn(II), but lacking experimental evidences and in-depth understandings. An international team — UNLV, HPSynC and HPSTAR of scientists co-led by Dr. Wenge Yang dug into this phenomenon and found that the giant volume collapse was coupled with the spin state transition of Mn(II) and a semiconductor-to-metal transition. This work is published online in Angew. Chem Int. Ed., 2016, doi:10.1002/anie.201605410.

Observation of sodium polyhydrides under pressure- Drs. Duckyoung Kim & Ho-Kwang Mao

JULY 29, 2016 — Combining synchrotron x-ray diffraction and Raman spectroscopy, a team co-led by HPSTAR scientist, Duckyoung Kim, report the first observation of formation of sodium polyhydrides (NaH3 and NaH7) between two diamond tips. These results are applicable to the design of new energetic solids and high-temperature superconductors based on hydrogen rich materials. These findings were reported in Nature Communications.

Band-gap narrowing together with carrier-lifetime prolongation in organic-inorganic trihalide perovskite – Drs Lingping Kong and Gang Liu

JULY 25, 2016 — A team of HPSTAR scientists led by Dr. Gang Liu utilized high-pressure technique to tune the electrical and photovoltaic performance in organic-inorganic hybride perovskites. 70%-100% carrier-lifetime increasing was found in mildly compressed organic-inorganic trihalide perovskite together with bad-gap narrowing. The story is just published on the July 21th edition of PNAS

Why is the simplest Fe-based superconductor the strangest? - Drs. Mahmoud Abdel-Hafiez and Xiaojia Chen

JULY 20, 2016 — By the in situ ARPES and a series of thermodynamic measurements, an international joint team co-led by Drs. Mahmoud Abdel-Hafiez and Xiaojia Chen from HPSTAR, realized a hump at elevated temperatures around 280K seems to be a standard feature of any degenerated semiconductors observed many times in various systems. This hump reflects the crossover between semiconducting and metallic behavior. Inelastic neutron-scattering experiments reveal both stripe and Néel spin fluctuations over a wide energy range at 110 K in FeSe. On entering the nematic phase, a substantial amount of spectral weight is transferred from the Néel to the stripe spin fluctuations. These stories are published in the July 19th edition of Nature Communications and in June 8th edition of Phys. Rev. B​.

Reversible bi-metastable phase switching in the VO2 system - Dr. Wenge Yang

JULY 18, 2016 —
By using the in situ synchrotron techniques at HPCAT and a series of self-designed experiments, an international joint team co-led by Dr. Wenge Yang from HPSTAR, realized a controllable phase switching between pressured-induced amorphization and thermal-driven recrytallization in VO2(B) nanosheets. They claimed that it was the first ever example of a structural memory effect observed in a strongly correlated material. The story is published in the July 18th edition of Nature Communications (doi:10.1038/ncomms12214).

Electron-rotor interaction in Organic-Inorganic Lead Iodide Perovskites - Dr. Gang Liu

JULY 14, 2016 — New work co-led by Dr. Gangliu from HPSTAR found carrier-rotor coupling effect in perovskite organic-inorganic hybrid lead iodide (CH3NH3PbI3) compounds from isotope effect. The discovery of the electron-rotor interaction would help to establish the theoretical foundation governing various energy transport, conversion, and storage sciences. The story is published in The Journal of Physical Chemistry Letters.

A new form of iron oxide controls hydrogen and oxygen cycles in the Earth interior - Dr. Ho-Kwang Mao

JUNE 9, 2016 — We breathe oxygen every day, but we might not know the Earth interior keeps approximately one million times oxygen more than the atmosphere. A team of HPSTAR scientists led by Ho-Kwang "Dave" Mao has discovered a new form of iron oxide - FeO2 that holds unprecedentedly large amount of oxygen, forming when the subducting plates carry the common “rust” (FeOOH) down into the deep mantle and controlling the flow of hydrogen and oxygen cycles in the Earth interior. Their findings are published in the June 9, 2016 issue of the journal Nature.

Squeeze electrons by diamond anvils: Discovery of a novel confined metal at high pressure - Dr. Yang Ding

MAY 25, 2016 — Insulator-metal transition (IMT), where a system changes from insulator to metal with a largely enhanced electrical conductivity, represents an important topic in contemporary condensed matter physics. New study led by scientist Dr. Yang Ding from Center for High Pressure Science and Technology (HPSTAR) found that the material Sr3Ir2O7 undergoes an IMT and becomes a confined metal at high pressure, showing metallicity in the crystal ab-plane but insulating along the c-axis. Such unusual phenomenon resembles the strange metal phase in cuprate high-temperature superconductors. This novel discovery opens up a new field for synthesizing functional materials. The work is published this week in Physical Review Letters.

Superconductivity at 46 K in FeSe - Dr. Mahmoud Abdel-Hafiez

FeSe and doped FeSe exhibit intriguing and distinctive properties, which are currently the research focus in the field of high temperature superconductors. Undoped FeSe possesses a nematic order below 90 K and superconductivity of 8 K. The most mysterious property here is not even the pressure or strain induced Tc increase, but a giant enhancement of the superconductivity at the FeSe/SrTiO3 interface, where SrTiO3 (STO) has nothing in common with magnetic interaction. It seems that STO provides phonons that enhance superconductivity in single-layered FeSe. International collaborations including HPSTAR physicist, Dr. Mahmoud Abdel-Hafiez, gave a systematic study in doping controlled FeSe system, proposing that the enhanced superconductivity is independent of the thickness of FeSe while intrinsic to FeSe. However, it is under heated debate whether the nematic order, below 90 K in FeSe, is driven by spin or orbital fluctuations. These issues in FeSe superconductors have been published this year in Nat. Mater. 15, 159 Nat. Mater. 15, 159 (2016), recently in Nat. Comm. 7, 10840 (2016), and last year in Phys. Rev. B 91, 165109 (2015).

Superconductivity in ZrTe5 under compression - Dr. Wenge Yang & Dave Mao

MARCH 2, 2016 — By multiple complementary methods, new work co-led by scientists from HPSTAR, Dr. Wenge Yang, and Dr. Dave Mao, are trying to investigate possible crystal structural as well as electronic transitions in 3D topological material ZrTe5 under compression. Two pressure induced superconducting phases are found in ZrTe5. And in situ high-pressure synchrotron X-ray diffraction and Raman spectroscopy together with theoretical calculations indicate that the two-state superconducting phases are correlated to two different crystal structural transitions at corresponding pressures.

From metal to insulator in dense CLi4 - Dr. Dave Mao

MARCH 1, 2016 — As a contrasting counterpart, lithium compounds may share some similar unexpected behaviors compared with hydrogen dominated materials at high pressures. New work co-led by HPSTAR scientist, Dr. Dave Mao, found that CLi4 becomes progressively less conductive and eventually insulating upon compression based on ab initio density-functional theory calculations.

Lithiation-induced stress in Li-ion batteries from micro-Raman Spectroscopy - Dr. Zhidan Zeng

FEBRUARY 25, 2016 — Stress is along standing challenge for the applications of silicon(Si) anodes in lithium(Li)ion batteries. Using in situ micro Raman spectroscopy, a team of scientists led by Dr. Zhidan Zeng at the Center for High Pressure Science & Technology Advanced Research (HPSTAR) measured the stress in silicon nanoparticles in a working Li-ion battery for the first time. This new study would be helpful in understanding how the nanostructured silicon anodes fracture during battery operation, and therefore provide guidance for their future design.

In-situ crystal structure determination of a minor phase in a multiphase system at megabar pressure - Dr. Li Zhang

FEBRUARY 16, 2016 — Multiple phases often coexist in a polycrystalline sample as a result of phase equilibrium in high-pressure petrological studies. Seifertite SiO2 likely exists as a minor phase near the Earth’s core-mantle boundary (CMB). Structure determination of a minor phase in a sample contained in a diamond anvil cell (DAC) has never been impossible using conventional powder or single crystal diffraction techniques. Utilizing the multigrain crystallography and newly developed procedures, new work led by HPSTAR scientists, Li Zhang et al., has overcome the difficulties and obtained the first in-situ single-crystal structure of seifertite being a minor phase in a polycrystalline sample at 129 GPa (Am. Mineral. 101, 231–234, 2016).

A general structural-property relationship in metallic glass - Charles Zeng

FEBRUARY 1, 2016 — Structure-property relationship is a central topic in materials science. In crystalline materials, the well-defined lattice structure or defects enable us to describe their properties quantitatively. The structure of glass is basically featureless, very few rigorous laws are currently known for defining its ‘disordered’ structure. Establishing general and exact rules regarding structure-property relationships in glass remain elusive. A breakthrough has been made by a international team led by Dr. Qiaoshi Zeng, a staff scientist from HPSTAR. This team established a general rule correlating the bulk properties (volume V) with most prominent atomic structure information (principle diffraction peak position q1) for metallic glasses, i.e. V∝(1/q1)2.5. It is shown that the 2.5 power law is strictly followed by any metallic glass with its volume tuned by pressure and/or composition. This general 2.5 power law is attributed to the well constrained structure change/modification inevitably happened during pressure and/or composition tuning of metallic glasses, which brings new insight into the structure of metallic glasses. These results are just published by PNAS.

Surface doping driven anomaly in the compression behaviors – Dr. Gang Liu

JANUARY 20, 2016 — Phase transitions in surface-modified TiO2 nanocrystals—An unprecedented surface doping-driven anomaly in the compression behaviors of nanocrystals has been discovered by a HPSTAR research group Led by Dr. Gang Liu. This work provides an unconventional and new degree of freedom in search for nanocrystals with novel tunable properties that can trigger applications in multiple areas of industry and provoke more related basic science research.

Dissociation products and structures of solid H2S - Dr. Lin Wang

JANUARY 11, 2016 — A record of highest critical temperature (Tc) of about 200 K — a temperature that actually exists on Earth’s surface, reported in H2S has lit a fire in superconductivity. This major breakthrough in superconductivity suggest that so high Tc is most likely due to the decomposition product, H3S, which was predicted to have the comparative value in Tc at high pressure. These proposals bring the decompositions conducts of H2S to another hot research topic. New study including Lin Wang, Yanwei Huang and Wentao Li, scientists from HPSTAR, utalizing experimental and theoretical simulations to probe decompositions of compressed H2S and possible stable structures, find that H4S3 is the major component of the dissociation products while there is just a small fraction of H3S.

Glimpse of metallic hydrogen - Dr. Ross Howie

JANUARY 7, 2016 — Driven by the predication of metallic hydrogen, the first and simplest element, there has been 80 years’ worth of combined theoretical and experimental effort to try to reach this predicted state in hydrogen. New breakthrough work from a team including Philip Dalladay-Simpson, and Ross T. Howie, two new scientists of HPSTAR, have carried out static compression on hydrogen and its isotopes above 380 gigapascals; higher pressure than any previous study. The work indicates another new phase, phase V, is detected in both hydrogen and hydrogen deuteride at pressures above 325 gigapascals at room temperature. Phase V could provide a glimpse of the theoretical predicated metallic hydrogen. This breakthrough discovery is published on January 07, 2016, in Nature.

Behind Electron Binding in Iron-based Superconductors - Dr. Mahmoud Abdel-Hafiez and Dr. Xiao-Jia Chen

DECEMBER 7, 2015 — International collaborations including HPSTAR physicists (Dr. Mahmoud Abdel-Hafiez and Prof. Xiao-Jia Chen) have studied one member of the recently discovered family of superconductors based on iron compounds and find this exotic form of superconductivity to have complex, multi-gap character. Additionally, the interplay between spin fluctuations, nematicity and superconductivity is well reported. A fact of principal importance for understanding the mechanisms of superconductivity is that the superconducting gap width never becomes zero around the constant-energy Fermi surface. Results of this work were published in two of the leading physical journals of the world, Physical Review B and Nature Material. Multiple techniques, in particular; specific heat, magnetization, transport, penetration depth, scanning tunneling microscopy and neutron scattering, have been used to achieve these studies.

Anomalous compression in CrAs - Dr. Lin Wang

NOVEMBER 17, 2015 — Using synchrotron X-ray diffraction combined with theoretical modeling, a team led by scientists from HPSTAR, Drs. ZhenhaiYu, Qingyang Hu, Chunyu Li, and Lin Wang performed detailed structure study on CrAs, an important bulk superconductivity material, at high pressures. They observed anomalous anisotropy with a pressure-induced isostructural transition. This crystal change agrees well with the conditions at which bulk CrAs becoming superconducting. The results shed light on the structural and related electronic responses to highpressure, which play a key role toward understanding the superconductivity ofCrAs. Their findings are published by recent PNAS (“Anomalous anisotropic compression behavior of superconducting CrAs under high pressure,” doi:10.1073/pnas.1520570112).

Different structure evolution in Bi2Se3 - Lin Wang

NOVEMBER 2, 2015 — Dr. Lin Wang and Zhenhai Yu from HPSTAR, led an international group of collaborators, found two pressure-induced structural phase transitions in topological insulator, Bi2Se3 in their recent study, which follows differently in the structure transformation compared with its isostructural compounds, Bi2Te3 and Sb2Te3.

Reversed resistivity change in GST - Dr. Lin Wang

OCTOBER 29, 2015 — Solid-state materials can be categorized by their ordering levels into crystalline, amorphous, quasi-crystalline, and crystalline but containing amorphous unites phases. Crystalline and amorphous materials are two most common matters in condensed-matter physics and materials science. Under ambient conditions, it is well known that the amorphous phase normally exhibits a higher resistivity, exceeding its crystalline counterpart by 2–5 orders of magnitude. New study indicated that such pronounced resistivity contrast is remarkably reduced and even reversed with increasing hydrostatic-like pressure in the prototypicalphase-change material GeSb2Te4 (GST).

Deformation twinning in silver nanocrystal - Dr. Wege Yang

OCTOBER 20, 2015 — There are many difficult challenges to track the deformation process in a single nanoscale crystal under external stresses. New research co-led by scientist from HPSTAR, Dr. Wenge Yang provides an in situ three-dimensional mapping of morphology and strain evolutions in a single-crystal silver nanocube under high-pressure conditions using coherent diffraction imaging (CDI) method.

Metallic glass: homogenous in appearance, fractal at heart - Dr. Qiaoshi Zeng

SEPTEMBER 18, 2015 — The atomic structure of glasses has been a long-standing unsolved mystery in condensed mater physics and materials science. A breakthrough in understanding the atomic structure of an important new category of glass — metallic glasses was made by a joint research team including staff scientist of HPSTAR, Dr. Qiaoshi Zeng . From multiple techniques, the team found that a specific fractal model — the percolation cluster packing could provide a perfect explanation of the 2.5 power law observed in the compression experiments of metallic glasses and a unified description of the atomic structure of metallic glasses from short range to macroscopic length scale for the first time. These results are just published by Science (DOI: 10.1126/science.aab1233).

Watching laser-shocked stishovite grow from amorphous silica in nanoseconds - Dr. Wenge Yang

SEPTEMBER 4, 2015 — Phase transitions have long been studied for centuries but little is known about the processes by which the atoms rearrange. New work from a team including HPSTAR scientist, Dr. Wenge Yang, performed in situ pump – probe x-ray diffraction measurements on shock-compressed fused silica, revealing the evolution of an amorphous to crystalline high pressure stishovite phase transition in nanoseconds. This is the first observation of shock-induced nucleation and growth of a high-pressure crystalline phase from an initially amorphous material. The study is published in recent Nature Communications (DOI: 10.1038/ncomms9191).

Anomalous Photovoltaic Response in CH3NH3PbBr3 – Dr. Wenge Yang

AUGUST 15, 2015 — The performance of solar cell newcomer materials called halide pervoskite has soared in recent years, which has rapidly surpassed that of both conventional dye-sensitized and organic photovoltaics. A recent research from a team of scientists including HPSTAR scientists Dr. Wenge Yang, Dr. Liuxiang Yang, Xiangting Ren and Dr. Lin Wang, using in situ high-pressure techniques to investigate the photovoltaic properties of organolead bromide perovskite CH3NH3PbBr3, found anomalous photovoltaic response associated with the pressure-induced phase transitions and reversible amorphization.

CMR induced in pure lanthanum manganite - Dr. Ho-Kwang Mao

AUGUST 12, 2015 — Colossal magnetoresistance (CMR) is a property with practical applications in a wide array of electronic tools including magnetic sensors and magnetic RAM. New research from a team including HPSTAR director Dr. Ho-Kwang “Dave” Mao, used high-pressure techniques to induce CMR for the first time in a pure sample, lanthanum manganite, LaMnO3.

Pressure induced metallization without structural transition in layered MoSe2 - Dr. Qiaoshi Zeng

JUNE 19, 2015 ­—The electronic structure transition (insulator to metal or semiconductor to metal transition) is generally accompanied or followed by a first-orderstructural transition. However, using multiple experimental techniques and ab-initio calculatios, new research from a group including Qiaoshi Zeng from HPSTAR find that the metallization process does not involve any crystal structure change in MoSe2, which allows its energy continuous tunability for potential opto-electronic or photovoltaic applications. Their work is published on recent Nature Communications (DOI: 10.1038/ncomms8312).

A promising novel phase for silicon anode lithium-ion battery - Dr. Zhidan Zeng

APRIL 14, 2015 — A team led by Dr. Zhidan Zeng at the Center for High Pressure Science & Technology Advanced Research (HPSTAR) synthesizes a new phase of Li15Si4 (beta-Li15Si4) under pressure. This beta-Li15Si4 phase shows higher packing density and superior mechanical properties than alpha-Li15Si4. This provides a new perspective on how to overcome the long-standing challenge in the application of silicon anodes for lithium-ion batteries.

Silica: Multiple Phases, other than a glassy structure - Qingyang Hu

MARCH 24, 2015 — Using synchrotron x-ray diffraction and theoretical modeling, the team from the Center for High Pressure Science & Technology Advanced Research (HPSTAR) including Qingyang Hu, Wenge Yang, and Ho-kwang Mao discovers four previously unknown phases of silicon dioxide, shedding light on the silica compression mechanism at room temperature. Their findings are published by Nature Communications (“Polymorphic phase transition mechanism of compressed coesite,” 6, 6630. DOI: 10.1038/ncomms7630).

Pressure induced seemed phase transition in metallic glass along with abnormal thermal expansions - Dr. Dawei Fan

FEBRUARY 2, 2015 — A team of scientists including Dr. Dawei Fan from HPSTAR, discovered a seemed first-order phase transition in Ce-based metallic glass along with abnormal thermal expansion at high pressure. This work indicate that pressure will be a very effctive method for investigating the structure or improving performance of metallic glasses for future applications.The related work is published on Nature Communications (“Hierarchical densification and negative thermal expansion in Ce-based metallic glass under high pressure”, DOI:10.1038/ncomms6703).

Losses in Ferroelectric Materials - Dr. Gang Liu

FEBRUARY 14, 2015 — Energy loss (or energy dissipation) is one of most critical issues in ferroelectric materials for engineer applications. This loss including elastic, piezoelectric and dielectric, associated with elasticity,dielectric relaxation and piezoelectric hysteresis in ferroelectrics, have involved many controversies/confusions in the past several decades. In a newly published study led by Dr. Gang Liu from Center of High Pressure Science and Technology Advanced Research, reviewed how the energy losses happened in ferroelectrics, fully tracked the origin of energy losses, and proposed a general theoretical model to describe the inherent relationships among elastic, dielectric, piezoelectric and mechanical losses.

A new phase in the deep lower mantle - Dr. Li Zhang

Utilizing a suite of latest advanced techniques, the research team from the Center for High Pressure Science and Technology Advanced Research (HPSTAR) reported a surprising discovery in mineral physics: Fe-bearing perovskite, which was considered as the major component in the lower mantle, is found to be unstable in the bottom third of the lower mantle. Therefore, the constitution of the lower mantle may be significantly different than previously thought. These results are published by Science on May 23, 2014.

A universal fractional noncubic power law for density in metallic glasses - Dr. Qiaoshi Zeng

Tuning with pressure, a research team led by Dr. Qiaoshi Zeng made a surprising discovery that the three-dimensional density of metallic glasses is not simply the cube of their one-dimensional average interatomic spacing, but varies with a universal 5/2 fractional power. The result is published by Phys. Rev. Lett. on May 8, 2014.

Detecting grain rotation at the nanoscale - Dr. Bin Chen

An international team of researchers, led by HPSTAR scientist Bin Chen have now succeeded in observing nano-scale plastic deformation by collecting x-ray diffraction (XRD) on poly-crystalline metal samples under high pressure in a radial diamond anvil cell (r-DAC). PNAS [PNAS 111 3350 ( 2014)]

Coherent diffraction imaging of nanoscale strainevolution in a single crystal under high pressure - Dr. Wenge Yang

Recently, a research group led by Dr. Wenge Yang, a scientist of HPSTAR, studied the Nano-size Effect in gold nano-particles under very high pressures. This research, published in the Nature Communications, is one of the first works that shows nanometer resolution imaging of a material in real conditions, and in real time.

Single-crystal structure of (Mg,Fe)SiO3 postperovskite in Earth D" layer - Dr. Li Zhang, Dr. Wenge Yang, Dr. Ho-Kwang Mao

JUNE 1, 2013 — Using a novel method for high-pressure single-crystal study, HPSTAR scientists Li Zhang, Wenge Yang ,and Ho-kwang Mao, in collaboration with colleagues have obtained the very first single-crystal structure of (Mg,Fe)SiO3 post-perovskite phase under high pressure corresponding to the condition in the Earth_sqlquote_s D′′ layer. This result is published by PNAS.

Probing the lower size limit of dislocation activity - Dr. Bin Chen

In a study including HPSTAR researchers, nano-crystals of nickel subjected to high pressure were found to suffer dislocation-mediated plastic deformation even when the crystals were only three nanometers in size. These results are published on Science.