Andriyevsky B, Barchiy I E, Studenyak I P, Kashuba A I, Piasecki M
Faculty of Electronics and Computer Sciences, Koszalin University of Technology, Śniadeckich str. 2, 75453, Koszalin, Poland.
Inorganic Chemistry Department, Uzhhorod National University, Pidhirna str. 46, Uzhhorod, 88000, Ukraine.
Sci Rep. 2021 Sep 24;11(1):19065. doi: 10.1038/s41598-021-98515-6.
The promising class of the environment-friendly thermoelectrics is the copper-based argyrodite-type ion-conducting crystals exhibiting just extraordinary low thermal conductivity below the glass limit associated with the molten copper sublattice leading to a softening of phonon modes. To explain why the argyrodite structure containing copper ions favors the low thermal conductivity, we have utilized the ab initio calculations of the electron, phonon, and thermoelectric properties of CuPS crystal in the framework of the density functional and Boltzmann transport theories. To obtain the reliable thermoelectric properties of CuPS, we take into account the dependence of the electron effective mass m on the redundant carrier concentration n. We propose to use the Burstein-Moss effect for the calculation of the electron effective mass m of a semiconductor. We have found the strong nonlinear character of copper atom vibrations in CuPS which exceeds substantially the similar values for phosphorous and sulfur atoms. The large vibration nonlinearity of the copper atoms found in CuPS explains the diffusion-like heat transfer and the relatively low coefficient of the lattice thermal conductivity (κ = 0.7 W/(m K)), which is favorable to achieve the large thermoelectric figure of merit.
一类很有前景的环境友好型热电材料是铜基硫银锗矿型离子传导晶体，其在低于与熔融铜亚晶格相关的玻璃极限温度时表现出极低的热导率，导致声子模式软化。为了解释含铜离子的硫银锗矿结构为何有利于低热导率，我们在密度泛函和玻尔兹曼输运理论框架下，利用了对CuPS晶体的电子、声子和热电性质的从头算。为了获得CuPS可靠的热电性质，我们考虑了电子有效质量m对多余载流子浓度n的依赖性。我们建议使用伯斯坦 - 莫斯效应来计算半导体的电子有效质量m。我们发现CuPS中铜原子振动具有很强的非线性特征，这大大超过了磷和硫原子的类似值。在CuPS中发现的铜原子的大振动非线性解释了类似扩散的热传递以及相对较低的晶格热导率系数（κ = 0.7 W/(m·K)），这有利于实现大的热电优值。
