Low-lying optical phonon modes in the filled skutterudite CeRu4Sb12
Low-lying optical phonon modes in the filled skutterudite CeRu4Sb12
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DOI：
10.1143/jpsj.75.123602
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发表时间：
2006-12-01
影响因子：
1.7
通讯作者：
Sato, H.
中科院分区：
文献类型：
--
作者：
Lee, C. H.;Hase, I.;Sato, H.
用非弹性中子散射方法研究了填充Skutterudite CeRu4Sb12的声子动力学。与CC原子的大振动相关的光学声子在相对较低的E能量下被观测到，与声学声子表现出抗腐蚀行为。我们认为，填充的Skutterudite中低的晶格热导率的起源可以归因于来自低能级光学声子的强烈的Umclapp散射。通过Born-von Karman力模型的分析，最近的Ce-Sb和Ce-Ru对的纵向力常数估计为0.025 mdyn/angstrom，而最近的Ru-Sb对的纵向力常数估计为1.4mdyn/angstrom，这表明CC原子与周围刚性RuSb_6-八面体笼子的结合非常弱。
The phonon dynamics of filled skutterudite CeRu4Sb12 have been studied at room temperature by inelastic neutron scattering. Optical phonons associated with a large vibration of Cc atoms are observed at a relatively low energy of E similar to 6 meV, and show anticrossing behavior with acoustic phonons. We propose that the origin of the low lattice thermal conductivity in filled skutterudites can be attributed to intensive Umklapp scattering originating from low-lying optical phonons. By an analysis based on a Born-von Karman force model, the longitudinal force constants of the nearest Ce-Sb and Ce-Ru pairs are estimated to be 0.025 mdyn/angstrom, while that of the nearest Ru-Sb pair is estimated to be 1.4mdyn/angstrom, indicating that the Cc atoms are bound very weakly to the surrounding rigid RuSb6-octahedron cages.