Structural Physics of Molecular Crystals Boron Triiodide and Tin Tetraiodide at High Pressure

验证分子晶体中各种高压现象的普遍性，对于发展基础材料科学和应用材料科学具有重要意义。在这项研究中，我们实验证明了在碘化硼中，分子的二聚化发生在压力诱导的结构变化上。基于密度泛函理论的第一性原理计算，成功地估算了超高压相四碘化锡的晶体结构。测量了四碘化锗在高温高压下的熔化曲线。带有扭结的曲线的独特形状强烈地暗示了在液相中可能存在两种不同的结构。

To verify universality of various high-pressure phenomena found in molecular crystals is of great importance in developing fundamental and applied material sciences. In this study, we demonstrated experimentally that in boron tiiodide the dimerization of the molecule took place upon the pressure-induced structural change. A crystal structure of a ultra-high pressure phase of tin tetraiodide was successfully estimated from a first-principles calculation based on a density-functional theory. We measured a melting curve of germanium tetraiodide at high pressures and high temperatures. Unique shape of the curve with kink strongly implied the possibility that two distinct structures could be existent in the liquid phase.