Mass Fluctuation Effect in Ti1-x Nb x S2 Bulk Compounds

The thermoelectric properties of Nb-substituted TiS2 compounds have been investigated in the temperature range of 300 K to 700 K. Polycrystalline samples in the series Ti1-x Nb (x) S-2 with x varying from 0 to 0.05 were prepared using solid-liquid-vapor reaction and spark plasma sintering. Rietveld refinements of x-ray diffraction data are consistent with the existence of full solid solution for x a parts per thousand currency sign 0.05. Transport measurements reveal that niobium can be considered as an electron donor when substituted at Ti sites. Consequently, the electrical resistivity and the absolute value of the Seebeck coefficient decrease as the Nb content increases, due to an increase in the carrier concentration. Moreover, due to mass fluctuation, the lattice thermal conductivity is reduced, leading to a slight increase of ZT values as compared with TiS2.