Second-order Raman spectroscopic study of lithium hydride and lithium deuteride at high pressure
Second-order Raman spectroscopic study of lithium hydride and lithium deuteride at high pressure
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DOI：
10.1103/physrevb.55.14818
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发表时间：
1997-06-01
影响因子：
3.7
通讯作者：
Chizmeshya, A
中科院分区：
文献类型：
--
作者：
Ho, AC;Hanson, RC;Chizmeshya, A
在室温下，测量了LiH和LiD的二阶拉曼光谱随压力的变化关系(V/V-0=-0.25)。对这些光谱中许多特征的归属进行了深入的研究。并与由中子散射数据得到的双声子色散曲线和同位素效应标度作了比较。此外，使用内部自洽程序来验证声子分配。大多数特征被分配给区域边界声子的组合。测定了许多区界声子的压强和体积依赖关系。这些声子包括X点处的所有声子以及L点和W点处的一些声子，其中大多数声子具有恒定的模格吕内森参数，而其他声子则表现出与体积有关的模格吕内森参数。在不同的模式之间，这些参数的大小有很大的变化。计算结果与从头计算结果吻合较好。
Second-order Raman spectra of LiH and LiD have been measured as functions of pressure up to 15 Gpa (Delta V/V-0= - 0.25) at ambient temperature. The assignments of the many features in these spectra have been thoroughly studied. The features have been compared with the two-phonon dispersion curves derived from neutron-scattering data and with isotope effect scaling. In addition, an internal self-consistency procedure is employed to validate the phonon assignments. Most of the features are assigned to combinations of zone boundary phonons. The pressure and volume dependence of many zone-boundary phonons have been determined. These include all of the phonons at the X point as well as some at the L and the W points, Most of these phonons have constant mode Gruneisen parameters, while others exhibit volume-dependent mode Gruneisen parameters. There is significant variation in the magnitude of these parameters between the various modes. The results are shown to be in good agreement with our ab initio calculations.