Tuning the crystal structure and electronic states of Ag2Se: Structural transitions and metallization under pressure

Zhao Zhao, Shibing Wang, Artem R. Oganov, Pengcheng Chen, Zhenxian Liu, Wendy L. Mao

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

Abstract

We performed synchrotron x-ray diffraction and infrared (IR) experiments combined with evolutionary structure predictions and band structure calculations on Ag2Se to ∼20 GPa. We present evidence for phase I (β-Ag2Se) as a potential three-dimensional topological insulator by its increase in optical band gap and the topologically nontrivial nature of its band structure. Higher pressures induce a triple-layer stacking pattern and significantly increase the crystallographic inequivalence of the two Ag sites, where P212121 phase I first reconstructs into a Pnma phase II, and then transforms into a topologically different Cmcm phase III. The radical changes in IR spectra and electronic band structures indicate the metallic nature of the high-pressure phases. Our results highlight the effects of pressure in tuning the crystal structure and electronic states of Ag2Se.

Original languageEnglish
Article number180102
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume89
Issue number18
DOIs
Publication statusPublished - 22 May 2014
Externally publishedYes

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