Enhancement in Thermoelectric Properties of TiS2 by Sn Addition

A series of Sn added TiS2 (TiS2:Sn (x) ; x = 0, 0.05, 0.075 and 0.1) were prepared by solid state synthesis with subsequent annealing. The Sn atoms interacted with sulfur atoms in TiS2 and formed a trace amount of misfit layer (SnS)(1+m)(TiS2-delta)(n) compound with sulfur deficiency. A significant reduction in electrical resistivity with moderate decrease in the Seebeck coefficient was observed in Sn added TiS2. Hence, a maximum power factor of 1.71 mW/m-K-2 at 373 K was obtained in TiS2:Sn-0.05. In addition, the thermal conductivity was decreased with Sn addition and reached a minimum value of 2.11 W/m-K at 623 K in TiS2:Sn-0.075, due to the impurity phase (misfit phase) and defects (excess Ti) scattering. The zT values increased from 0.08 in pristine TiS2 to an optimized value of 0.46 K at 623 K in TiS2:Sn-0.05.