Prof. Yuejian Wang [Oakland University, USA]

Title: My tenure at Oakland University: a zigzag road to high-pressure research

Time: 2:00 - 3:00 PM, Monday, May 9, 2016

Place: Auditorium Room 410, Building 6, HPSTAR (Shanghai)

Host: Dr. Wenge Yang

Abstract:

In the first half of the presentation, I will elucidate the construction of high-pressure physics lab at the Physics Department of Oakland University, its current capability for conducting frontier research, and the research projects being undertaken now. In the last half of the presentation, I will focus on the study of Sb2S3 (stibnite) under high pressure, which was accepted a few days ago by Sci. Rep. The Sb2S3 is a well-known binary semiconductor with an optical band gap Eg ~ 1.7 eV. Recently, Sb2S3 was shown to undergo an electronic topological transition (ETT) near 5 GPa observed during high pressure Raman spectroscopic and resistivity measurements. Our high-pressure synchrotron X-ray and Raman studies illustrated a second-order iso-structural transition at the same pressure, ~5 GPa, evidenced by noticeable compressibility changes in distinct Raman-active modes, in the lattice parameter axial ratios, in the unit cell volume, as well as in specific interatomic bond lengths and bond angle. The coincidence of ETT and structural transition suggests that pressure affects the crystal structure as well as the electronic state in Sb2S3. Upon increasing pressure further, the second high-pressure modification appearing above 15 GPa appears to trigger a structural disorder at ~20 GPa; full decompression from 53 GPa leads to the recovery of an amorphous state.

Biography of the Speaker:

Yuejian Wang

Assistant Professor

Physics Department, Oakland University

Postdoc, Yale University (2009-2011)

Postdoc, Los Alamos National Laboratory (2006-2009)

Ph.D, Texas Christian University (2006)

B. E. Tsinghua University, Beijing, China (1996)