Pressure-Induced Structural Transitions in Liquid Metals and Semiconductors

本项目的目的是研究原子具有共价键、离子键、金属键和弱键等多种键的液体的局域结构和物理性质与压力的关系。结果进行了讨论，在有关的压力引起的相变在结晶phase.X-ray衍射测量在高压下进行了使用同步辐射与能量色散的方法。压力由多砧装置产生。在液态碘化银中观察到一个急剧的结构变化。另一方面，在液体CuI，液体CuBr和液体CuCl中观察到连续的结构变化。常压下，液态卤化铜的局域结构为四面体结构，随着压力的增加，其局域结构逐渐转变为八面体结构。液体的转变压力从CuCl增加到CuI，类似于晶体。研究了卤化铜的局域结构与压力的关系， ...更多信息 在由二维共价键网络组成的IV-VI族化合物中，GeSe、GeTe、SnTe和PbTe的体积收缩各向异性，且随温度的升高而增大，随温度的升高而减小。在液态GeTe、液态PbTe和液态SnTe中，分别在1.8 ~ 4.0 GPa、2.6 ~ 4.0 GPa和1.6 ~ 3.3 GPa的压力范围内，观察到了结构参数随压力的急剧变化，当压力超过转变压力时，几个结构参数的压力导数值发生变化。压力下的测量表明，随着温度的升高，在GaSb和CdTe的电导率急剧增加。然而，对电导率随压力变化的详细测量尚未完成，从这些结果可以得出结论：液体局域结构的压力变化取决于原子间键的离子性，液体IV-VI族化合物的压力诱导结构变化不同于晶体。少

The purpose of this project is to investigate the pressure dependence of the local structure and physical properties of liquids in which atoms have several kinds of bonds, such as covalent bond, ionic bond, metallic bond and weak bond. Results are discussed in relation to the pressure-induced phase transitions in the crystalline phase.X-ray diffraction measurements under high pressure were performed by using synchrotron radiations with an energy-dispersive method. Pressure was generated by a multi-anvil apparatus. A sharp structural change was observed in liquid AgI. On the other hand, a continuous structural change was observed in liquid CuI, liquid CuBr and liquid CuCl. The local structure of liquid copper halides consists of tetrahedron structure at normal pressure and changes to octahedron structure with increasing pressure. The transition pressure for the liquids increases from CuCl to CuI, similar to the crystals. The pressure dependence of the local structure of copper halides i … More n which atoms have highly ionic bonds is similar to that of crystal, which is similar to that of liquid CdTe with highly ionic bonds.In the liquid IV-VI compounds, whose crystal structure consists of two dimensional network of the covalent bonds, an anisotropic volume contraction was observed in liquid GeSe, liquid GeTe, liquid SnTe and liquid PbTe. A sharp structural change with pressure was observed in liquid GeTe between 1.8 GPa and 4.0 GPa, in liquid PbTe between 2.6 GPa and 4.0 GPa, in liquid SnTe between 1.6 GPa and 3.3 GPa and above the transition pressure, the pressure derivative of several structural parameters changes its value.A new technique for electrical resistance measurements under high pressure was developed. Measurements under pressure shows the drastic increase of the conductivity with increasing temperature in GaSb and CdTe. However, the detailed pressure dependence measurements of the conductivity was unfinished.From these results it is concluded that the pressure variation of the local structure of liquids depends on the ionicity in the bonds between atoms and the pressure-induced structural change of liquid IV-VI compounds is different from that of crystals. Less