Thermoelectric Properties for a Suspended Microribbon of Quasi-One-Dimensional TiS3

Transition-metal trichalcogenides MX3 (M = Ti, Zr, Nb, Ta; X = S, Se) are well-known inorganic quasi-one-dimensional conductors. Among them, we have investigated the thermoelectric properties of titanium trisulfide TiS3 microribbon. The electrical resistivity rho, thermal conductivity kappa, and thermoelectric power S were measured using 3 omega method. The weight mean values were found to be rho = 5 m omega m and kappa = 10 W K-1 m(-1) along the one-dimensional direction (b-axis) of the TiS3 microribbon. Combined with the thermoelectric power S = -530 mu V K-1, the figure of merit was calculated as ZT = 0.0023. This efficiency is the same as that of randomly oriented bulk TiS3. We also estimated the anisotropy of sigma and kappa using the present results and those for randomly oriented bulk material. The obtained weak anisotropy for TiS3 is attributable to strong coupling between triangular columns consisting of TiS3 units. These experimental results are consistent with theoretical results obtained using density functional theory (DFT) calculations.