Authors: C. S. Lue and Y. H. Tseng, Y. K. Kuo
We report a study of the temperature-dependent electrical resistivity, Seebeck coefficient, and thermal conductivity in the Sr0.9-zCa0.1Si2 (z=0, 0.07, 0.13, and 0.2) alloys to elucidate the vacancy effect on the thermoelectric performance, characterized by the figure-of-merit, ZT. It is found that the room-temperature electrical resistivity and Seebeck coefficient decrease through the introduction of vacancies onto the Sr sites of Sr0.9Ca0.1Si2. It is important that the room-temperature thermal conductivity of these samples was substantially reduced upon introducing vacancies. Such a promising result leads to a significant enhancement in the ZT value as compared to the non-vacancy compound Sr0.9Ca0.1Si2. Namely, the highest room-temperature ZT value of 0.27 was obtained for Sr0.77Ca0.1Si2, about two times larger than that of Sr0.9Ca0.1Si2.
Keywords: intermetallic silicade; thermoelectric; figure-of-merit