Tuning conduction properties and clarifying thermoelectric performance of P-type half-heusler alloys TiNi1−xCoxSn (0 ≤ x ≤ 0.15)

• Published in: Solid state sciences 2024-11, Vol.157, Article 107708
• Main Authors: Yamazaki, Kosuke, Sam, Sopheap, Okamoto, Yoichi, Nakatsugawa, Hiroshi
• Format: Article
• Language: English
• Subjects: Conduction properties; Half-heusler; P-type; Thermoelectric performance; TiNiSn
• ISSN: 1293-2558
• DOI: 10.1016/j.solidstatesciences.2024.107708

TiNiSn is an N-type thermoelectric material with a high-power factor composed of low toxicity and abundant elements. TiNiSn also shows P-type electrical conduction by hole doping. In this study, we tune the conduction properties of TiNi1−xCoxSn (0 ≤ x ≤ 0.15) with Co substitution at the Ni site. The samples were prepared by the arc melting method, and thermoelectric properties were investigated up to 800 K. The results of the Hall effect and the Seebeck coefficient measurements indicate that the majority of charge carriers changes from electrons to holes at x ≥ 0.03, suggesting that Co acts as an acceptor. We report for the first time that Ti0.994Ni1.00Co0.051Sn1.01 exhibits ZT = 0.12 at 675 K. This work reveals that Ti0.994Ni1.00Co0.051Sn1.01 could be a potential P-type thermoelectric material operating at high temperatures. [Display omitted] •We investigate ZT and thermoelectric properties of TiNi1−xCoxSn.•Thermoelectric properties change N-type to P-type after Co3%-doped.•Co acts as an acceptor impurity and increases hole carrier density.•Co5%-doped TiNiSn can be used as a candidate for P-type thermoelectric materials.