Prof. Alexander V. Soldatov [Lulea University of Technology, Sweden]

Title: Graphene vs graphite at high pressure: search for the “elusive” high pressure phase

Time: 10:00 - 11:00 AM, Thursday, September 21, 2017

Place: Conference room 410, HPSTAR (Shanghai)

Host: Ho-Kwang Mao

Abstract

Report on graphite conversion into a superhard metastable phase at high pressure [1] sparked high interest in both theoretical and experimental high-pressure community to unveiling the nature of this state of carbon. Massive theoretical efforts resulted in prediction of different structural motifs of this “elusive” phase whereas experimental efforts largely lag behind in validation of the proposed structures and/or provided inconsistent results. Shall we expect observation of this transition in a few layer graphene? On the other hand how does a single layer graphene behave at high pressure? Most of the studies on this system were done on stressed supported material. We review current state of knowledge of the subject and report on the first Raman study of free standing graphene monolayer (membrane) at high hydrostatic pressure in a diamond anvil cell (DAC). The modes' Gruneisen parameter was determined and compared to that reported for uni-and bi-axial strained material and theoretical predictions. The graphene membrane behaviour at high hydrostatic pressure differs drastically from that of the single layer material deposited on a substrate which obscures the intrinsic material’s properties of the material.

In the second part of the lecture a brief overview of the first set of beam lines at MAX IV synchrotron radiation facility which are being commissioned now will be made.

       References

       [1] Mao, W. L. et al. Science, 302, 425 (2003).

Biography of the Speaker:





Prof. Alex Soldatov focuses his research on synthesis and characterization of novel carbon-based materials and disordered systems from nanostructured carbon precursors (fullerenes, nanotubes, graphene) using high pressure and high temperature. He has background and expertise in low temperature and high pressure experiment and actively uses synchrotron and  neutron spallation sources in his research. He received his MS in engineering physics from Kharkov Polytechnic University, Ukraine in 1984 and PhD in low temperature physics from the Institute for Low Temperature Physics & Engineering, Ukrainian Academy of Sciences in 1995. Thereafter he took during 1995-99 postdoc positions in Umea university, Sweden, University of Sussex, UK and Research Centre Karlsruhe, Germany before joining Prof. Silvera group at the Department of Physics, Harvard university as a research associate in 1999. In 2002 he moved back to Europe to take a full faculty position at Dept. of Applied Physics and Mechanical Engineering, Lulea university of technology, Sweden and he is also affiliated with the Dept. of Physics, Harvard.  

Prof. Soldatov is recipient of Shubnikov Prize for research on thermal properties of Hydrogens and low temperatures. He was Royal Society/NATO visiting scholar at University of Sussex and was awarded number of times visiting professor scholarships in Lyon and Nancy university and Karlsruhe Institute of Technology. His publication record includes Science, Nano Letters, Nanoscale, PRL, PRB, etc. He is regularly invited to speak at major international conferences in the field.

Prof. Soldatov served several times as European High Pressure Research Group (EHPRG) Committee member and since 2015 he is elected member of the Executive Committee of the AIRAPT. He is a member of the Swedish Universities Reference/Advisory Group on MAX IV Synchrotron Radiation Facility in Sweden

The other areas of Prof. Soldatov research interest include molecular electronics devices, sensors, quantum phenomena in molecular nanostructures, single molecule spectroscopy, tribo-chemistry/physics.