Preparation and thermoelectric properties of ternary rare earth sulfide γ-Ce3–xEuxS4

The effect of Eu-substitution on the density and thermoelectric properties of ternary sulfide Ce3–xEuxS4 (0≤x≤0.8) compacts was investigated. Ce3–xEuxS4 powders were prepared via the sulfurization of the oxide using CS2 gas at 1473 K. The pressureless sintered Ce3–xEuxS4 compacts in the atmosphere were crystallized in the γ-phase. The density of the Ce3–xEuxS4 compacts increased with the increasing of Eu-substitution. Eu-substitution yielded a higher Seebeck coefficient and lower electrical resistivity. The highest value of the thermoelectric power factor of 1.41×10−4 W/K2m was obtained for the Ce2.2Eu0.8S4 compact at 673 K. It indicated that Eu-substitution was effective for improving thermoelectric properties of Ce3–xEuxS4.