Chemical pressure effect on thermoelectric properties of Ca and Ba substituted SrSi2 alloys

Abstract

We report the study of temperature-dependent electrical resistivity, Seebeck coefficient, and thermal conductivity of the Sr1−xCaxSi2 and Sr1−xBaxSi2 alloys to elucidate the chemical pressure effect on the thermoelectric performance, characterized by the figure-of-merit, ZT. It is found that the room-temperature electrical resistivity and thermal conductivity are slightly reduced through the substitution of Ca and Ba (x < 0.10) onto the Sr sites of SrSi2. Moreover, the room-temperature Seebeck coefficients of these samples are substantially enhanced upon substitution. These promising results lead to a significant enhancement in the ZT value of the substituted SrSi2 alloys as compared to the parent compound SrSi2. Namely, the highest room-temperature ZT values of ∼0.17 and ∼0.11 were obtained for the Sr0.92Ca0.08Si2 and Sr0.93Ba0.07Si2 alloys, much larger than that of pure SrSi2.