Ma Weiliang, Record Marie-Christine, Tian Jing, Boulet Pascal
Aix-Marseille University, University of Toulon, CNRS, IM2NP, Marseille, France.
Aix-Marseille University, CNRS, MADIREL, Marseille, France.
Phys Chem Chem Phys. 2021 May 19;23(19):11300-11313. doi: 10.1039/d1cp00270h.
The Pb2Bi2Te5 compound has been reported in the literature with two stacking sequences -Te-Pb-Te-Bi-Te-Bi-Te-Pb-Te- and -Te-Bi-Te-Pb-Te-Pb-Te-Bi-Te- labelled in this work as A and B, respectively. The electronic and the thermoelectric properties of the Pb2Bi2Te5 compound with the 2 different stacking sequences have been determined from a series of first principles calculations using density functional theory (DFT). The related compounds PbTe and Bi2Te3 have also been investigated for comparison. Different exchange-correlation functionals have been tested, without spin-orbit coupling, which has been found to have important effects. The elastic moduli, dielectric constants, Born effective charges, and phonon dispersion within the quasi-harmonic approximation have also been calculated and based on these calculations results, the thermal conductivity has been determined by solving the Boltzmann transport equation. Additionally, the QTAIM theory was employed to explain the differences in the properties of the 2 stackings. The most interesting compound for thermoelectric applications has been found to be Pb2Bi2Te5 with the stacking B sequence. The highest zT values have been found to be 4.02 in the a-axis direction and 2.26 in the c-axis one.
文献中已报道了Pb2Bi2Te5化合物存在两种堆积序列，在本工作中分别标记为A和B，即-Te-Pb-Te-Bi-Te-Bi-Te-Pb-Te-和-Te-Bi-Te-Pb-Te-Pb-Te-Bi-Te-。通过一系列使用密度泛函理论（DFT）的第一性原理计算，确定了具有这两种不同堆积序列的Pb2Bi2Te5化合物的电子和热电性质。还对相关化合物PbTe和Bi2Te3进行了研究以作比较。在未考虑自旋轨道耦合的情况下测试了不同的交换关联泛函，发现自旋轨道耦合具有重要影响。还计算了准谐近似下的弹性模量、介电常数、玻恩有效电荷和声子色散，并基于这些计算结果，通过求解玻尔兹曼输运方程确定了热导率。此外，采用量子拓扑原子分子理论（QTAIM）来解释两种堆积结构性质上的差异。已发现对于热电应用而言，最有趣的化合物是具有堆积B序列的Pb2Bi2Te5。已发现最高的zT值在a轴方向为4.02，在c轴方向为2.26。
