Study on crystal structures and compressibilities of solid hydrogen and transition metal hydrides at high pressures and high temperatures

（1）固体氢：在30 K-395 K和6 GPa-100 GPa的温压范围内，进行了X射线衍射实验。在该温度-压力范围内观察到由六方晶系晶格分配的衍射峰。得到了30、150、300和395 K下氢的摩尔体积随压力的变化关系。在20 GPa以上的压力下，摩尔体积几乎不依赖于温度。晶格常数和六方晶系晶格的c/a比不断下降，通过增加在I-II相边界的压力。（2）金属氢化物：在7 GPa以上的压力下，金属铼在hcp晶格的间隙中掺入氢，形成金属氢化物。在六方晶系晶格中，氢原子沿c轴沿着每隔一层掺入，形成反CdI_2结构。钨金属在25 GPa以上的压力下也结合了氢。在氢化物中，金属亚晶格的排列没有改变，而钨亚晶格从bcc变为 ...更多信息 当氢结合到钨金属中时，掺入的氢原子随机占据六方晶系的八面体空穴。本文研究了作为地核主要成分的Fe-10%Ni合金的压缩性和与氢的反应。该合金在高于6 GPa的压力下掺入氢，并从bcc结构转变为dhcp结构。另一方面，原始合金在15 GPa下从bcc转变为hcp。这些转变类似于纯铁。然而，在合金的情况下，转变压力更高。（3）多兆巴和压力刻度：在300 GPa压力下测量了金刚石压砧的一级拉曼光谱。拉曼带的高频边缘由样品室中的压力的函数表示。本文提出了应用压力相关性来测定几兆巴压力区的压力。少

(1)Solid hydrogen : At temperature-pressure range of 30K-395K and 6GPa-100GPa, X-ray diffraction experiments were performed. The diffraction peaks assigned by an hcp lattice were observed in that temperature-pressure range. Pressure dependences of molar volume of hydrogen at 30, 150, 300 and 395 K were obtained. At pressures above 20 GPa, the molar volume is scarcely dependent on temperature. Lattice constants and the c/a ratio of an hcp lattice were continuously decreased by increase in pressure across the I-II phase boundary.(2)Metal hydrides : Rhenium metal incorporated hydrogen in interstices of its hcp lattice and formed a metal hydride at pressures above 7GPa. Hydrogen is incorporated in every second layer along the c-axis of an hcp lattice, which results in an anti-CdI_2 structure. Tungsten metal also incorporated hydrogen at pressures above 25GPa. In the rhenium hydride the arrangements of a metal sublattice did not change, while the tungsten sublattice changed from a bcc to an … More hcp when hydrogen was incorporated in a tungsten metal. The incorporated hydrogen atom randomly occupied the octahedral hole of the hcp lattice. The compressibility and the reaction with hydrogen of Fe-10%Ni alloy, which is considered to be the principal constituent of the earth's core, were investigated. The alloy incorporated hydrogen at pressure above 6 GPa and transformed from a bcc to a dhcp structure. On the other hand, the pristine alloy transformed from a bcc to an hcp at 15GPa. These transformations are similar to those of pure Fe. The transition pressures, however, are higher in the case of the alloy.(3)Multimegabar and a pressure scale : The first-order Raman spectra of diamond anvils used in a gasketed high-pressure cell were measured at pressures up to 300GPa. The high-frequency edge of the Raman band is represented by a function of pressure in the sample chamber. The application of the pressure dependence for pressure determination up to multimegabars pressure region is proposed. Less