[21p-P09-1~10] 9.4 Thermoelectric conversion

[21p-P09-9] Thermal stability and thermoelectric properties of Cu₇Ti_xV_1−xSnS₈

〇Shuya Kozai¹, Koichiro Suekuni¹, Seiya Takahashi², Eiji Nishibori², Philipp Sauerschnig³, Michihiro Ohta³, Michitaka Ohtaki¹ (1.Kyushu Univ., 2.Univ. of Tsukuba, 3.AIST GZR)

Keywords:thermoelectric materials, sulfides, semiconductor

We have synthesized a new semiconductor, Cu₇VSnS₈, with a sphalerite-derived structure in our previous study. The substitution of Ti⁴⁺ for V⁵⁺ increased the hole carrier concentration, leading to the enhanced dimensionless figure of merit ZT of 0.6–0.7 at 673 K. The electrical resistivity and Seebeck coefficient of the substituted systems exhibited large increases in their temperature coefficients upon heating and a hysteresis between heating and cooling processes. In this study, we investigated the mechanism of the anomalous behavior in electronic properties by means of thermogravimetry/differential thermal analysis and powder X-ray diffraction.