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Nature of thermoelectric properties occurring in defected Sn2P2S6 chalcogenide crystals
CrystEngComm ( IF 2.6 ) Pub Date : 2020/02/25 , DOI: 10.1039/c9ce02017a
T. Babuka 1, 2, 3, 4, 5 , K. Glukhov 6, 7, 8, 9 , A. Kohutych 6, 7, 8, 9 , Yu. Vysochanskii 6, 7, 8, 9 , M. Makowska-Janusik 1, 2, 3, 4, 5
Affiliation  

Detailed first-principles calculations were performed to explain the physical nature of the thermoelectric properties occurring in Sn2P2S6 (SPS) crystals with deviation from stoichiometry. Consequently, a computational model was formulated to calculate the thermoelectric parameters of nonstoichiometric SPS crystals in the paraelectric phase by taking into account the calculations of cohesive energy, Ecoh, crystal formation energy, Ef, and vacancy formation energy, Evf, using the DFT and DFT+U methods. Using the Boltzmann formula, the relative concentrations of different types of point defects in bulk SPS systems were determined. These data were used to calculate the temperature behavior of nonstoichiometric SPS crystals. Experimental temperature dependence of conductivity was determined. Consequently, the concentration of charge carriers, their mobilities, and temperature behaviors of the Seebeck coefficient in the SPS crystal could be determined. The experimentally obtained dependencies of the thermoelectric effect demonstrated an agreement with the experimental measurements, confirming the validity of the proposed model of point defect formation in the material under consideration, thereby proving the unexpected properties of the SPS crystal.

中文翻译:

Sn2P2S6硫族化物晶体中发生热电性质的性质

进行了详细的第一性原理计算,以解释Sn 2 P 2 S 6(SPS)晶体中发生的热电特性的物理性质,其偏离化学计量比。因此,计算模型配制通过考虑内聚能,的计算来计算在顺电相的非化学计量SPS晶体的热电参数ë COH,晶体形成能,ë ˚F,和空位形成能,ê VF,使用DFT和DFT + U方法。使用玻尔兹曼公式,确定了整体SPS系统中不同类型点缺陷的相对浓度。这些数据用于计算非化学计量SPS晶体的温度行为。确定了电导率的实验温度依赖性。因此,可以确定SPS晶体中载流子的浓度,其迁移率和塞贝克系数的温度行为。实验获得的热电效应依赖性证明了与实验测量结果的一致性,从而确认了所考虑材料中点缺陷形成模型的有效性,从而证明了SPS晶体的出乎意料的特性。
更新日期:2020-03-30
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