Department of Physics, Yantai University, Yantai 264005, People's Republic of China.
Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China.
J Phys Condens Matter. 2023 Feb 17;35(15). doi: 10.1088/1361-648X/acb983.
Metal phosphides are stable and have excellent electrical characteristics, their high thermal conductivity has prevented them from being used as thermoelectric materials. In this paper, the thermoelectric transport properties of XLiP (X = Sr Ba) are investigated on the basis of first-principles calculations, Boltzmann transport equation and self-consistent phonon theory. In addition, we also consider the effect of quartic anharmonicity on the thermal transport properties and lattice dynamics of SrLiP and BaLiP. The strong anharmonicity of the two compounds make the lattice thermal conductivity decrease rapidly with the increase of temperature. At 300 K, the lattice thermal conductivity of SrLiP and BaLiP on the()-axis is only 2.98 and 2.93 WmK, respectively. Due to its excellent electron transport properties, it has greater conductivity in the() axis. Finally, due to the energy pocket and anisotropy at the bottom of the conduction band, the n-type maximum ZT values of trapped SrLiP and BaLiP on the() axis are 0.87 and 0.94 at 900 K, respectively. The high thermoelectric performance of both compounds encourages further studies on the thermoelectric properties of metal phosphides.
金属磷化物稳定且具有优异的电学特性，但它们的高热导率阻碍了它们在热电材料中的应用。本文基于第一性原理计算、玻尔兹曼输运方程和自洽声子理论，研究了 XLiP（X=Sr、Ba）的热电输运性质。此外，我们还考虑了四次非谐性对 SrLiP 和 BaLiP 的热输运性质和晶格动力学的影响。这两种化合物的强非谐性使得晶格热导率随温度的升高而迅速下降。在 300 K 时，SrLiP 和 BaLiP 在()-轴上的晶格热导率分别只有 2.98 和 2.93 WmK。由于其优异的电子输运性质，在()轴上具有更大的电导率。最后，由于导带底部的能谷和各向异性，在()轴上受陷 SrLiP 和 BaLiP 的 n 型最大 ZT 值分别在 900 K 时达到 0.87 和 0.94。这两种化合物的高热电性能鼓励进一步研究金属磷化物的热电性能。
