Phase‐Transformation‐Induced Giant Deformation in Thermoelectric Ag<sub>2</sub>Se Semiconductor
Qi Liang, Dongwang Yang, Fanjie Xia, Hui Bai, Haoyang Peng, Ruohan Yu, Yonggao Yan, Danqi He, Shaowen Cao, Gustaaf Van Tendeloo, Guodong Li, Qingjie Zhang, Xinfeng Tang, Jinsong Wu
Abstract
Abstract In most semiconducting metal chalcogenides, a large deformation is usually accompanied by a phase transformation, while the deformation mechanism remains largely unexplored. Herein, a phase‐transformation‐induced deformation in Ag 2 Se is investigated by in situ transmission electron microscopy, and a new ordered high‐temperature phase (named as α ′‐Ag 2 Se) is identified. The SeSe bonds are folded when the Ag + ‐ion vacancies are ordered and become stretched when these vacancies are disordered. Such a stretch/fold of the SeSe bonds enables a fast and large deformation occurring during the phase transition. Meanwhile, the different SeSe bonding states in α‐, α ′‐, β‐Ag 2 Se phases lead to the formation of a large number of nanoslabs and the high concentration of dislocations at the interface, which flexibly accommodate the strain caused by the phase transformation. This study reveals the atomic mechanism of the deformation in Ag 2 Se inorganic semiconductors during the phase transition, which also provides inspiration for understanding the phase transition process in other functional materials.