High thermoelectric performance in the multi-valley electronic system Zr3Ni3−xCoxSb4 and the high-mobility Zr3Ni3−xCuxSb4

Abstract

We report synthesis and thermoelectric performance of the p-type Zr3Ni3−xCoxSb4 and the n-type Zr3Ni3−xCuxSb4, which are derived from the same parent semiconductor Zr3Ni3Sb4. We found a high thermoelectric performance for both the p-type compound (the figure-of-merit ZT is 0.52 at 760 K) and the n-type compound (ZT = 0.41 at 670 K). ZT of the p-type compound exceeded the value of the p-type half-Heusler compounds consisting of similar elements. The Hall-coefficient measurements indicate that the high ZT in the n-type compounds is a consequence of the high electron mobility of 52.4 cm2/Vs. In contrast, the p-type compounds showed higher ZT in spite of much lower mobility. We discuss the mechanism for the high ZT in the p-type compound from the viewpoint of the multi-valley band structure.