Improved thermoelectric performance of n-type half-Heusler MCo1-xNixSb (M = Hf, Zr)

• Published in: Materials today physics Vol. 1; pp. 24 - 30
• Main Authors: He, Ran, Zhu, Hangtian, Sun, Jingying, Mao, Jun, Reith, Heiko, Chen, Shuo, Schierning, Gabi, Nielsch, Kornelius, Ren, Zhifeng
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2017
• Subjects: Half-Heusler; n-type; Thermoelectric; ZrCoSb; ZrCoSb; Thermoelectric; n-type; Half-Heusler
• ISSN: 2542-5293; 2542-5293
• DOI: 10.1016/j.mtphys.2017.05.002

The MCoSb-based (M = Hf, Zr) half-Heusler compounds were recognized as a promising p-type thermoelectric (TE) material for more than 2 decades although the base compound is intrinsically n-type. Here we investigate the TE properties of Ni-substituted n-type MCoSb. The anomalous changes of carrier concentration and lattice thermal conductivity with higher amount of Ni indicate the presence of atomic disorder. Peak power factor of ∼33 μW cm−1 K−2 and peak ZT of 0.6 are obtained in ZrCo0.9Ni0.1Sb. Further substitute Zr by Hf suppresses the lattice thermal conductivity and yields a peak ZT exceeding 1 in the composition Zr0.5Hf0.5Co0.9Ni0.1Sb at 1073 K. Thus the MCoSb compounds possess promising TE properties by both n- and p-type doping, which is unique among the half-Heusler based TE materials. [Display omitted] •The MCoSb-based half-Heusler compounds were turned into n-type through Ni substitution at the Co site.•The mechanisms of the observed anomalous variations of carrier concentration and lattice thermal conductivity were discussed.•Peak ZT exceeding 1 was obtained in Hf0.5Zr0.5Co0.9Ni0.1Sb at 1073 K.