Guest host interaction and low energy host structure dynamics in tin clathrates
Guest host interaction and low energy host structure dynamics in tin clathrates
复制标题
锡包合物中的客体相互作用和低能主体结构动力学
DOI：
10.1063/1.4793081
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发表时间：
2013
影响因子：
3.2
通讯作者：
M. Christensen
中科院分区：
文献类型：
--
作者：
Sebastian Christensen;Lasse Bjerg;A. Kaltzoglou;F. Jurányi;T. Fässler;T. Unruh;M. Christensen
用粉末非弹性中子散射（INS）研究了Rb_8Sn_（44）□2和Cs_8Sn_（44）□2两种含空位的二元笼形化合物。实验和计算结果表明，Rb和Cs的振摇能相近，均为<$ωCs/<$ωRb|实验= 0.98（1）和<$ωCs/<$ωRb|计算值= 1.0，尽管有显著的质量差异：mCs/mRb=1.6，这表明客体-主体相互作用对于所研究的系统是不可忽略的。对于Rb 8 Sn 44 □2，在~ 3.5 meV处观察到低能声子模式，低于文献中归因于客体原子的声子模式。3.5毫电子伏的模式被解释为具有显着的光谱重量的Sn主机原子的基础上的温度依赖性和出版的理论声子计算的比较。锡笼形物的低热导率的记录可以归因于主体结构动力学，而不是客体原子的晃动。
The two binary clathrates with vacancies (□) Rb8Sn44□2 and Cs8Sn44□2 have been examined using powder inelastic neutron scattering (INS). Rattling energies of Rb and Cs are found to be similar by both experiment and calculations, ℏωCs/ℏωRb|Exp.=0.98(1) and ℏωCs/ℏωRb|Calc.=1.0, despite the significant mass difference: mCs/mRb=1.6, which shows that guest-host interaction is non-negligible for the studied system. For Rb8Sn44□2, a low energy phonon mode is observed at ≈3.5 meV, below the phonon mode which in the literature is attributed to the guest atom. The 3.5 meV mode is interpreted to have significant spectral weight of Sn host atoms based on temperature dependence and comparison with published theoretical phonon calculations. The record of low thermal conductivity of the tin clathrates can be attributed to the host structure dynamics rather than the guest atom rattling.