Thermoelectric properties of image prepared by CS2 sulfurization Original Research Article

Titanium disulfide (TiS2) powder was prepared by sulfurizing TiO2 powder with CS2 gas at 1073 K for 4 h. Because CS2 gas is a powerful sulfurizing agent for TiO2, CS2 sulfurization can be performed at a low temperature. The TiS2 powder thus prepared was first mixed with sulfur powder in a mass ratio of 1:0.04 and pressure sintered at 973 K for 1 h under a uniaxial pressure of 50 MPa in vacuum. The addition of a small amount of sulfur powder to the TiS2 powder prevents sulfur deficiency in the sintered compact, resulting in the formation of a near-stoichiometric Ti1.008S2 composition. X-ray diffraction patterns show that the crystalline ab-axis is preferentially oriented perpendicular to the pressing direction. The Seebeck coefficient, electrical resistivity and thermal conductivity of the oriented TiS2 sintered compacts with near-stoichiometric and sulfur-poor (titanium-rich) compositions were measured in the temperature range 300–723 K. The thermoelectric figure of merit ZT was enhanced by prevention of sulfur deficiency and formation of the oriented texture. The highest ZT of 0.34 was observed at 663 K in Ti1.008S2 for the direction perpendicular to the pressing axis.