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.
The crisis of energy prompts researchers to explore green/sustainable energy. Thermoelectric materials (such as Bi2Te3and Bi2Se3), as the typical sustainable energy materials used in thermoelectric systems for cooling or heating could also be applied to regenerate electricity from waste heat at electric power plants. While topological insulators (TIs) are electronic materials that have a bulk band gap like ordinary insulators, but feature conducting states on their surface, which are one of the most exciting topics in condensed-matter physics, with a wide range of potential practical applications. Topological insulators (TIs) found in the thermoelectric materials such as Bi2Te3, Sb2Te3, and Bi2Se3 hit the physics spotlight as another exciting newcomer, which act like insulators on the interior, while conduct on the surface.
For isostructural materials, it’s nature to assume a similar/same structure transition pathway under the same conditions. Still, different crystal structure or electronic structure transitions are detected in some isostructural materials. The team led by Dr. Wang, utilized diamond-anvil cell technology, x-ray diffraction, Raman spectroscopy combined with theoretical simulations to track the structure evalution in Bi2Se3, one of the important TIs. At ambient conditions, Bi2Se3 isostructural to Bi2Te3 and Sb2Te3. The researchers found that the TI in question, Bi2Se3 displays a progressive structural evolution compared with Bi2Te3 and Sb2Te3. It transferred from an ambient rhombohedra structure to a monoclinic phase and eventually to a body-centered tetragonal phase instead of the recently reported disordered body-centered cubic (BCC) phase. “This remarkable difference in atomic radii of Bi and Se in Bi2Se3 may explain why Bi2Se3 shows different structural behavior from the isocompounds Bi2Te3 and Sb2Te3” , said Dr. Zhenghai Yu, whose research mainly focus on gaining better understanding of the nature of phase transition in functional materials.
The work is published in Sci. Rep. 5, 15939; doi: 10.1038/srep15939 (2015).
Caption: Structural evolution in Bi2Se3 under high pressure.