Pressure induced solid-solid reconstructive phase transition in LiGaO2 dominated by elastic strain
Pressure induced solid-solid reconstructive phase transition in LiGaO2 dominated by elastic strain
复制标题
LiGaO2 中由弹性应变主导的压力诱导固-固重构相变
DOI：
10.1103/physrevb.97.014106
复制
发表时间：
2018
影响因子：
3.7
通讯作者：
He Duanwei
中科院分区：
文献类型：
--
作者：
Hu Qiwei;Yan Xiaozhi;Lei Li;Wang Qiming;Feng Leihao;Qi Lei;Zhang Leilei;Peng Fang;Ohfuji Hiroaki;He Duanwei
GaN和AlN中的石墨-金刚石和纤锌矿-岩盐的压力诱导固-固重构相变发生在明显高于平衡共存预期的压力下，并且它们的转变路径总是彼此不一致。这表明，在固-固重构相变的基本成核和生长机制知之甚少。在这里，我们提出了一个弹性应变占主导地位的机制，在一个重建的相变，到，基于situonin高压角色散X射线衍射和单晶拉曼散射。这一机制表明，压力诱导的固-固重构相变既不是纯扩散，也不是纯扩散，如传统假设，但组合。在相变早期，伴随着共格形核，大的弹性应变积累。沿沿着和方向的弹性应变太大而不能被剪应力松弛，因此出现了一个中间结构，它减小了弹性应变，使转变在能量上有利。在较高的压力下，当弹性应变变小到足以被松弛时，相变开始，共格形核被Li和Ga原子无序的半共格形核所取代。
Pressure induced solid-solid reconstructive phase transitions for graphite-diamond, and wurtzite-rocksalt in GaN and AlN occur at significantly higher pressure than expected from equilibrium coexistence and their transition paths are always inconsistent with each other. These indicate that the underlying nucleation and growth mechanism in the solid-solid reconstructive phase transitions are poorly understood. Here, we propose an elastic-strain dominated mechanism in a reconstructive phase transition,to, based onin situhigh-pressure angle dispersive x-ray diffraction and single-crystal Raman scattering. This mechanism suggests that the pressure induced solid-solid reconstructive phase transition is neither purely diffusionless nor purely diffusive, as conventionally assumed, but a combination. The large elastic strains are accumulated, with the coherent nucleation, in the early stage of the transition. The elastic strains along theanddirections are too large to be relaxed by the shear stress, so an intermediate structure emerges reducing the elastic strains and making the transition energetically favorable. At higher pressures, when the elastic strains become small enough to be relaxed, the phase transition tobegins and the coherent nucleation is substituted with a semicoherent one with Li and Ga atoms disordered.