Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 20015, USA.
J Chem Phys. 2012 Dec 14;137(22):224503. doi: 10.1063/1.4769794.
Pressure induced densification in a molecular arsenic sulfide glass is studied at ambient temperature using x-ray scattering, absorption and Raman spectroscopic techniques in situ in a diamond anvil cell. The relatively abrupt changes in the position of the first sharp diffraction peak, FSDP, and the pressure-volume equation of state near ∼2 GPa suggest a phase transition between low- and high-density amorphous phases characterized by different densification mechanisms and rates. Raman spectroscopic results provide clear evidence that the phase transition corresponds to a topological transformation between a low-density molecular structure and a high-density network structure via opening of the constituent As(4)S(3) cage molecules and bond switching. Pressure induced mode softening of the high density phase suggests a low dimensional nature of the network. The phase transformation is hysteretically reversible, and therefore, reminiscent of a first-order phase transition.
采用原位同步辐射 X 射线散射、吸收和拉曼光谱技术，在金刚石压腔中研究了室温下砷化硫分子玻璃的压力诱导致密化。在约 2GPa 附近，第一尖锐衍射峰（FSDP）的位置和压力-体积状态方程的相对突然变化表明存在由不同致密化机制和速率控制的低密度和高密度非晶相之间的相转变。拉曼光谱结果提供了明确的证据，表明该相转变对应于组成 As(4)S(3)笼分子的打开和键的转换，从低密度分子结构到高密度网络结构的拓扑转变。高密度相的压力诱导模式软化表明网络具有低维性质。该相转变是滞后可逆的，因此类似于一级相变。
