Thermoelectric properties of β-Indium sulfide with sulphur deficiencies

We prepared a bulk sample of beta-In2S3, which was predicted to possess high thermoelectric performance by ab initio calculations, using pulsed current sintering technique and conventional solid reaction method. The composition of prepared sample was In2S2.94, and the deficient in sulfur led to n-type behaviors of thermoelectric properties. The absolute value of Seebeck coefficient was vertical bar S vertical bar = 220 mu V/K at room temperature, and monotonically increased with temperature up to 600K then moderately decreased. The thermal conductivity was relatively low (0.68W m(-1) K-1) at 700 K presumably due to the phonon scattering with anharmonic lattice vibrations. The dimensionless figure of merit ZT consequently reached 0.38 at 700 K. We also estimated the value of ZT as a function of carrier concentration, and found that p-type beta-In2S3 has potential to possess a large value of ZT exceeding 1.4. (C) 2015 AIP Publishing LLC.