Inherent instability by antibonding coupling in AgSbTe2
Inherent instability by antibonding coupling in AgSbTe2
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DOI：
10.7567/jjap.55.041801
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发表时间：
2016-03
影响因子：
1.5
通讯作者：
H. Shinya;A. Masago;T. Fukushima;H. Katayama‐Yoshida
中科院分区：
文献类型：
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作者：
H. Shinya;A. Masago;T. Fukushima;H. Katayama‐Yoshida
本文从电子结构的角度描述了三元硫系化合物AgSbTe_2的一种固有的不稳定性。我们的计算，这是基于集群扩展方法，建议九个稳定的晶体结构，涉及最稳定的结构与对称性。用广义微扰法计算的有效对相互作用指出，这些结构的稳定性来源于Ag-Te-Sb原子键线性排列的数目。AgSbTe_2具有特殊的电子结构，其价带顶的主要成分是Te-5 p反键态.这种反键贡献导致固有的不稳定性，使得系统自发地形成由电荷补偿缺陷复合物引起的各种突变相。我们建议，这些突变阶段发挥了重要作用，在AgSbTe 2的热导率和热电效率。
In the present paper, an inherent instability in the ternary chalcogenide compound AgSbTe2 is described from the electronic structure viewpoint. Our calculations, which are based on the cluster expansion method, suggest nine stable crystal structures involving the most stable structure with symmetry. The effective pair interactions calculated by the generalized perturbation method point out that the stability of these structures originates from the number of linear arrangements of the Ag–Te–Sb atomic bonds. Moreover, it is found that AgSbTe2 has a special electronic structure, where the dominant components of the top of the valence band are the Te-5p antibonding states. Such an antibonding contribution leads to an inherent instability, such that the system spontaneously forms various mutation phases caused by charge-compensated defect complexes. We propose that these mutation phases play an important role in the thermal conductivity and thermoelectric efficiency in AgSbTe2.