Understanding phase evolutions and the underlying mechanism under external stimuli is of fundamental importance for novel material discovery. Herein, combining angular dispersive X-ray diffraction and first-principles pathway sampling, we found that the ZnTe alloy undergoes a quasi-reconstructive transition to a metastable rocksalt phase under deviatoric stress. The rocksalt ZnTe has reconstructed chemical bonds and dendrite crystal morphology. It also suffers more severe thermodynamic hysteresis compared with the same experiments under hydrostatic pressure. However, the phase transition towards the rock-salt phase is still described by relatively small atomic displacements and is slightly first order; thus, it is neither fully displacive nor fully reconstructive. The quasi-reconstructive transition in ZnTe narrows its electronic bandgap and may provide insights into the semiconductor–metal transition in II–VI alloys in general.
Yukai Zhuang, Lei Wu, Bo Gao, Zhongxun Cui, Huiyang Gou, Dongzhou Zhang, Shengcai Zhu, Qingyang Hu, “Deviatoric stress-induced quasi-reconstructive phase transition in ZnTe,” J. Mater. Chem. C 8 (11), 3795-3799 (2020). DOI: 10.1039/c9tc06334j
Phase transition kinetics in ZnTe at 10 GPa. (a) Calculated energy barrier from ZnTe-I to II, ZnTe-II to III and ZnTe-II to rocksalt ZnTe. Hollow sphere represents the evolution of coordination numbers on the transition pathway. (b) Charge density map showing the reconstruction of atomic bonding in ZnTe-III and rocksalt ZnTe. Anisotropic compression along the b axis of ZnTe-III and the subsequent relaxation along a and c axes leads to the formation of 6-coordinated rocksalt ZnTe.
(a) The SEM image of the initial sample. (b) ZnTe recovered from 25.9 GPa at non-hydrostatic conditions. (c) ZnTe recovered from 25.5 GPa at quasi-hydrostatic conditions.