Zou Yongtao, Zhang Wei, Li Xuefei, Ma Maining, Li Xing'ao, Wang Chun-Hai, He Bin, Wang Shanmin, Chen Zhiqiang, Zhao Yusheng, Li Baosheng
Academy for Advanced Interdisciplinary Studies, and Department of Physics, Southern University of Science and Technology, Shenzhen, 518055, China.
Phys Chem Chem Phys. 2018 Apr 25;20(16):11430-11436. doi: 10.1039/c8cp00084k.
Here, we report a high-pressure study of orthorhombic structured β-Sb2O3 (valentinite) by the combination of synchrotron in situ X-ray diffraction and first-principles theoretical calculations at pressures up to 40.5 GPa. Our results reveal that the metastable β-Sb2O3 undergoes an isostructural phase transition at high pressure, yielding a distorted β phase at 7-15 GPa through symmetry breaking and structural distortion as inferred from our XRD analyses and DFT theoretical calculations where pressure-induced elasticity softening is observed at pressures of 7-15 GPa. At pressures higher than 15 GPa, a new high-pressure monoclinic phase is discovered from the current synchrotron X-ray diffraction data. Upon further compression up to ∼33 GPa, the monoclinic Sb2O3 starts to lose its long-range order and forms an amorphous component coexisting with the monoclinic one. To further explore the structural instability and understand the origin of pressure-induced phase transitions in β-Sb2O3 upon compression, we have performed first-principles calculations to track the evolution of its phonon velocities, density of states and phonon dispersion curves under high pressure. Our results may play an important role in determining the local structures as well as their structural relationship among sesquioxides.
在此，我们通过同步辐射原位X射线衍射与第一性原理理论计算相结合的方法，对正交结构的β-Sb₂O₃（黄锑矿）在高达40.5 GPa的压力下进行了高压研究。我们的结果表明，亚稳的β-Sb₂O₃在高压下经历了同结构相变，根据我们的XRD分析和DFT理论计算推断，在7-15 GPa时通过对称破缺和结构畸变产生了扭曲的β相，在7-15 GPa的压力下观察到压力诱导的弹性软化。在高于15 GPa的压力下，从当前的同步辐射X射线衍射数据中发现了一种新的高压单斜相。进一步压缩至约33 GPa时，单斜相的Sb₂O₃开始失去其长程有序性，并形成与单斜相共存的非晶成分。为了进一步探索结构不稳定性并理解β-Sb₂O₃在压缩时压力诱导相变的起源，我们进行了第一性原理计算，以追踪其在高压下声子速度、态密度和声子色散曲线的演变。我们的结果可能在确定倍半氧化物的局部结构及其结构关系方面发挥重要作用。
