Doping effects of Mg for In on the thermoelectric properties of β-In2S3 bulk samples

Abstract

β-In2S3 was developed as a potential thermoelectric material both experimental and computational. In this work, Mg doped In2S3 samples were prepared by conventional solid-state reaction method followed by pulsed current sintering. For In2-xMgxS3 (0 ≤ x ≤ 0.20), the prepared samples maintains tetragonal β-In2S3 phase while α-In2S3 with cubic structure were obtained at x ≥ 0.30. The both Mg and S concentrations were less than the nominal values, and the lack of S naturally lead to an effective increase of electron concentration in the bands crossing the Fermi level. The lattice thermal conductivity was reduced by the Mg-substitution, and the value of ZT reached 0.53 at 700 K for x = 0.05, which is 1.4 times larger than that of non-doped sample.