Synthesis process and thermoelectric properties of the layered crystal structure SnS2

Abstract

This work reports on the thermoelectric properties of bulk SnS₂, which shows a similar composition and layered crystal structure to the extensively studied SnS and SnSe. The synthesis process for mechanical alloying (MA) SnS₂ was also investigated. The SnS₂ compound was formed in the reaction between SnS and S, after the formation of SnS using Sn and S as raw materials. However, single-phase SnS₂ appears to be difficult to obtain by MA because Sn₂S₃ is produced when milling times are extended. Nevertheless, a pure-phase SnS₂ bulk is achieved by further spark plasma sintering. The pristine SnS₂ bulk shows an n-type conductive characteristic and a moderate absolute Seebeck coefficient between 100 and 700 μV/K. However, with a low figure of merit value ZT, the thermoelectric property is poor because of the low electrical conductivity of below 0.2 S/cm and the relatively high thermal conductivity of above 1.5 W/mK. Further, the electrical conductivity is enhanced and the thermal conductivity decreases significantly after Ag doping. An enhanced ZT value of 0.01 is achieved which is two times higher than pristine one.