具有低热导率热电材料的第一性原理研究

发布时间：2018-06-17 15:10

本文选题：第一性原理计算 + 笼状化合物　；参考：《杭州电子科技大学》2015年硕士论文

【摘要】：本文主要的研究对象是Ba8T16P30(T=Cu,Au)、ATSb(A=Li,Cs,T=Zn,Cd)、In4X3(X=Se,Te)等几种典型的具有低热导率的热电材料,利用基于密度泛函理论的第一性原理,采用两种不同的交换势函数研究了它们的电子结构和热电特性,并与实验结果做了对比。结合塞贝克系数和电阻率找出性能最优时所对应的载流子浓度,从而为实验研究优化其热电性能提供参考和指导。研究所取得的主要成果总结如下:(1)首次利用第一性原理研究了笼状化合物Ba8T16P30(T=Cu,Au)的电子结构和热电特性。这两种化合物的塞贝克系数均为正的,表明它们均是P型半导体。两种化合物的输运性质计算实验结果与现有文献报道结果定性一致。(2)对ATSb(A=Li,Cs,T=Zn,Cd)的晶体结构进行优化,发现化合物Li CdSb和CsZnSb比Li ZnSb的能量更低,首次从理论上预测了这两种新化合物的存在。计算结果表明,LiCdSb为半导体,而CsZnSb呈现出金属性质。(3)采用修正的Becke-Jonson(mBJ)交换势,计算了In4Se3和In4Te3电子结构,继而计算了它们的塞贝克系数随温度和载流子浓度的变化。很好地再现了不同文献所给出的实验结果。揭示了不同实验结果存在显著差异的原因主要来自不同制备工艺造成的材料的载流子浓度的差异。
[Abstract]:In this paper, several typical thermoelectric materials with low thermal conductivity, such as Ba8T16P30TCU, ATSbCsTZN, Tznznzcdznzncdzhuanzhuang (In4X3), are studied by using the first principle based on density functional theory (DFT) and using two different exchange potential functions to study their electronic structure and thermoelectric properties, and the results are as follows: (1) in this paper, the electronic structure and thermoelectric properties of these materials are studied by using the first principle based on density functional theory (DFT), and two different exchange potential functions are used. The results are compared with the experimental results. The carrier concentration corresponding to the optimum performance can be found by combining Seebeck coefficient and resistivity, thus providing a reference and guidance for the experimental study on the optimization of its thermoelectric performance. The main results obtained are summarized as follows: (1) the electronic structure and thermoelectric properties of cage compound Ba8T16P30 (TCU) are studied by first principle. The Seebeck coefficients of these two compounds are positive, indicating that they are P-type semiconductors. The calculated results of transport properties of the two compounds are qualitatively consistent with the reported results in the literature. (2) the crystal structure of ATSbSb LiCsTsTznznzncdcdd) is optimized. It is found that the energy of the compounds Li CdSb and CsZnSb are lower than that of Li ZnSb, and the energy of these compounds is lower than that of LiZnSb. The existence of these two new compounds is predicted theoretically for the first time. The calculated results show that LiCdSb is a semiconductor, while CsZnSb exhibits metal properties. The modified Becke-JonsonsonmBJ) exchange potential is used to calculate the electronic structures of In4Se3 and In4Te3, and the variation of their Sebek coefficients with temperature and carrier concentration is calculated. The experimental results given in different literatures are well reproduced. It is revealed that the main reasons for the significant differences in experimental results are due to the differences in carrier concentration of materials due to different preparation processes.
【学位授予单位】：杭州电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34

【参考文献】