A study of the vibrational and thermoelectric properties of silicon type I and II clathrates
A study of the vibrational and thermoelectric properties of silicon type I and II clathrates
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DOI：
10.1063/1.3078157
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发表时间：
2009-02
影响因子：
3.2
通讯作者：
J. Li;Chun-lei Wang;Meng Wang;H. Peng;Ruizhi Zhang;M. L. Zhao;Jianjun Liu;Jianxiu Zhang;L. Mei
中科院分区：
文献类型：
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作者：
J. Li;Chun-lei Wang;Meng Wang;H. Peng;Ruizhi Zhang;M. L. Zhao;Jianjun Liu;Jianxiu Zhang;L. Mei
采用第一原理计算来研究I型和II型硅包合物。得到了两种包合物的声子谱和红外光谱。我们发现了Si 46的一个局域振动模式，其频率为375.0 cm−1，其中该模式的振动局限于六边形链中。两种笼形物的热容与金刚石相Si（d-Si）的热容相同。当温度低于100 K时，包合物的德拜温度高于d-Si的德拜温度，而在高温（>100 K）时，两种包合物的德拜温度均低于d-Si的德拜温度。在低温下，笼形物的平均自由程（λ）和热导率（κ）均大于d-Si。在300-1000 K的温度区间内，包合物的Seebeck系数（S）高于d-Si，但两种包合物的σ/τ值均低于d-Si。
First principles calculations are employed to investigate both type I and II silicon clathrates. The phonon and infrared spectra of both types of clathrate are obtained. We find a localized vibrational mode of Si46 whose frequency is 375.0 cm−1, where the vibration in the mode localizes in the hexagonal chain. The heat capacity of both clathrates is the same as that of the diamond phase Si (d-Si). When the temperature is lower than 100 K, the Debye temperatures of the clathrates are higher than that of d-Si; however, the Debye temperatures of both clathrates at high temperature (>100 K) are lower than that of the d-Si. The mean free paths (λ) and thermal conductivities (κ) of the clathrates are larger than those of d-Si at low temperature. The Seebeck coefficients (S) of the clathrates are higher than that of d-Si in the temperature interval 300–1000 K; however, both clathrates exhibit a lower value of σ/τ when compared to the d-Si.