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Development of high pressure techniques above 100 GPa and their application to materials in the core

100 GPa以上高压技术的开发及其在堆芯材料中的应用

基本信息

批准号：
12126204
负责人：
KAWAMURA Haruki
金额：
$ 28.1万
依托单位：
Himeji Institute Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

1 Structural phase transition of solid hydrogen and metal hydrides Optical studies have demonstrated that solid hydrogen exhibits three crystalline phases. Orientationaly disordered phase-I (hcp structure) transformed through phase-II into phase-III, which is considered to be an ordered phase. The transition boundary between phase-I and phase-II, which is reported to exhibit a strong isotope effect, shifts to lower pressure for deuterium. Solid n-D_2 transforms into phase-II around 28 GPa at 15 K. X-ray powder diffraction experiments at 15 K were performed at pressure up to 57 GPa. The results suggest that the center of each hydrogen molecule in phase-II is still on the hcp lattice point. The pressure-volume relation for deuterium at 15 K was also measured, and the bulk modulus and its pressure derivative are determined as 0.386 GPa and 6.43, respectively. Powder X-ray diffraction experiments of Re-hydrogen system were performed at high pressures and room temperature. Under pressure ab … More ove 5 GPa, rhenium metal (hcp) incorporated hydrogen in octahedral interstices of an hcp lattice. Superstructure reflection lines, which were produced by the displacements of rhenium atoms from the hcp lattice points, were observed. We conclude that hydrogen is incorporated in every second layer along the c-axis of an hcp lattice, which results in an anti-CdI_2 type structure.2 Pressure scale by the use of a diamond anvil When a diamond anvil cell is used for pressure generation, the ruby gauge that the pressure is determined from the wavelength shift of the fluorescence line of a ruby by pressure is commonly used. Above 100 GPa, however, the equation of state of gold or platinum is used for pressure determination because the fluorescence weakens abruptly. In this case, the unit cell volume of metals cannot be determined without synchrotron radiation sources at such high pressures. We measured the Raman shift of the diamond used as a anvil up to 220 GPa and proposed a new pressure scale by the use of a diamond anvil. Less

1固体氢与金属氢化物的结构相变光学研究表明，固体氢有三种晶相。定向无序的I相(HCP结构)通过II相转变为III相，这被认为是有序相。据报道，第一相和第二相之间的过渡边界表现出很强的同位素效应，但对于重氢来说，过渡边界移动到了较低的压力。在15K下，固相n-D2在28 Gpa左右转变为II相。结果表明，第二相中每个氢分子的中心仍在hcp晶格点上。测量了15K时的压力-体积关系，测得体积弹性系数为0.386 Gpa，压力导数为6.43。在常温高压下进行了Re-H体系的粉末X射线衍射实验。在压力下ab…在5 Gpa以上，金属Re(HCP)在HCP晶格的八面体空隙中结合了氢。观察到了由Re原子从hcp晶格点位移而产生的超结构反射线。我们得出的结论是，氢沿着hcp晶格的c轴每隔一层就被掺入，形成了一种反CdI_2型结构。2使用金刚石顶压腔产生压力时，通常使用红宝石压力计，它是根据红宝石压强的荧光线的波长移动来确定压力的。然而，在100 Gpa以上，金或铂的状态方程用于压力测定，因为荧光突然减弱。在这种情况下，在没有同步辐射光源的情况下，无法在如此高的压力下测定金属的单位晶胞体积。我们测量了作为压头的金刚石的拉曼位移，并提出了一种使用金刚石压头的新的压力表。较少