Gudelli Vijay Kumar, Kanchana V, Vaitheeswaran G
Department of Physics, Indian Institute of Technology Hyderabad, Ordnance Factory Estate, Yeddumailaram-502 205, Telangana, India.
J Phys Condens Matter. 2016 Jan 20;28(2):025502. doi: 10.1088/0953-8984/28/2/025502. Epub 2015 Dec 18.
We present here the thermoelectric properties of olivine-type Fe2GeCh4 (Ch = S, Se and Te) using the linear augmented plane wave method based on first principles density functional calculations. The calculated transport properties using the semi-local Boltzmann transport equation reveal very high thermopower for both S and Se-based compounds compared to their Te counterparts. The main reason for this high thermopower is the quasi-flat nature of the bands at the valence and conduction band edges. The calculated thermopower of Fe2GeS4 is in good agreement with the experimental reports at room temperature, with the carrier concentration around 10(18)-10(19)cm(-3). All the investigated systems show an anisotropic nature in their electrical conductivity, resulting in a value less than the order of 10(2) along the a-axis compared to the b- and c-axes. Among the studied compounds, Fe2GeS4 and Fe2GeSe4 emerge as promising candidates with good thermoelectric performance.
我们基于第一性原理密度泛函计算，采用线性缀加平面波方法，在此展示了橄榄石型Fe2GeCh4（Ch = S、Se和Te）的热电性质。使用半局域玻尔兹曼输运方程计算得到的输运性质表明，与基于Te的化合物相比，基于S和Se的化合物具有非常高的热电势。这种高热电势的主要原因是价带和导带边缘能带的准平坦性质。Fe2GeS4计算得到的热电势在室温下与实验报告吻合良好，载流子浓度约为10(18)-10(19)cm(-3)。所有研究的体系在电导率方面都表现出各向异性，导致沿a轴的值比b轴和c轴小一个数量级，小于10(2)。在研究的化合物中，Fe2GeS4和Fe2GeSe4成为具有良好热电性能的有前景的候选材料。
