Enhancement of Thermoelectric Behavior of La0.5Co4Sb12−x Te x Skutterudite Materials

Abstract

In this work, the effects of Te doping on the microstructure and thermoelectric properties of the partially filled skutterudite La0.5Co4Sb12 compounds have been examined. La0.5Co4Sb12−x Te x skutterudite compounds were synthesized by a combination of the mechanical alloying technique and spark plasma sintering processing, which resulted in partial substitution of Te atoms in Sb sites. The XRD results showed that all the Te-doped bulk samples were composed of a major phase of the Co4Sb12 skutterudite with a small amount of CoSb2 and Sb as the secondary phases. Thermoelectric measurements of the consolidated samples were examined in a temperature range of 300 K to 800 K (27 °C to 527 °C). With the La0.5Co4Sb11.7Te0.3 sample, the highest absolute Seebeck coefficient of 300 μV/K was obtained at 404 K (131 °C) and the lowest lattice thermal conductivity of 2 W/mK was achieved at 501 K (228 °C). Moreover, the minimum electrical resistivity of 19.7 μΩm was recorded at 501 K (228 °C) for La0.5Co4Sb11.5Te0.5 sample. The effect of the secondary phases was negligible for the electrical resistivity, and between 0.5 to 1.6 pct for the thermal conductivity. Thus, the highest figure of merit, ZT = 0.47, was obtained at 792 K (519 °C) for La0.5Co4Sb11.5Te0.5 sample due to a significant reduction in electrical resistivity and a moderate increase in the absolute Seebeck coefficient.