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Pressure-Induced Structural Transitions in Liquid Metals and Semiconductors

液态金属和半导体中压力引起的结构转变

基本信息

批准号：
16340110
负责人：
TSUJI Kazuhiko
金额：
$ 6.98万
依托单位：
Keio University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16340110/
关键词：
liquids high pressure phase transitions structure synchrotron radiations x-ray diffraction

项目摘要

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

本项目的目的是研究具有共价键、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。用同步辐射和能量色散的方法对高压下的X射线衍射进行了测量。压力是由多砧板装置产生的。在液态AgI中观察到明显的结构变化。而在CuI、CuBr和CuCl3种液体中观察到连续的结构变化。液态卤化铜的局部结构在常压下由四面体结构组成，随压力的增加由八面体结构转变为八面体结构。从CuCl到CuI，液体的转变压力增大，与晶体相似。卤化铜的局域结构与压力的关系I…在具有二维共价键网络的液体IV-VI化合物中，观察到液体GeE、液体GeTe、液体SNTe和液体PbTe的体积收缩各向异性。在1.8~4.0 Gpa压力范围内，液体Get、2.6~4.0 Gpa压力范围内的PbTe液体、1.6~3.3 Gpa压力范围内的液体SNTe以及转变压力以上的液体SNTe中，结构参数的压力导数随压力的变化而急剧变化。压力测量表明，GaSb和CdTe的电导率随温度的升高而急剧增加。这些结果表明，液体局部结构的压力变化取决于原子间键的离子性，液体IV-VI化合物的压力诱导结构变化不同于晶体的结构变化。较少