Experimental and computational study of the role of defects and secondary phases on the thermoelectric properties of TiNi1+xSn (0 ≤ x ≤ 0.12) half Heusler compounds
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2023-07-30
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en
Pages
9
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Nanotechnology, Volume 34, issue 31
Abstract
The half Heusler TiNiSn compound is a model system for understanding the relationship among structural, electronic, microstructural and thermoelectric properties. However, the role of defects that deviate from the ideal crystal structure is far from being fully described. In this work, TiNi1+xSn alloys (x = 0, 0.03, 0.06, 0.12) were synthesized by arc melting elemental metals and annealed to achieve equilibrium conditions. Experimental values of the Seebeck coefficient and electrical resistivity, obtained from this work and from the literature, scale with the measured carrier concentration, due to different amounts of secondary phases and interstitial nickel. Density functional theory calculations showed that the presence of both interstitial Ni defects and composition conserving defects narrows the band gap with respect to the defect free structure, affecting the transport properties. Accordingly, results of experimental investigations have been explained confirming that interstitial Ni defects, as well as secondary phases, promote a metallic behavior, raising the electrical conductivity and lowering the absolute values of the Seebeck coefficient.Description
Funding Information: Authors acknowledge the CINECA award under the ISCRA initiative, for the availability of high-performance computing resources and support. S. Casassa, L. Maschio, M. Baricco and A. Castellero acknowledge support from the Project CH4.0 under the MUR program “Dipartimenti di Eccellenza 2023-2027” (CUP: D13C22003520001). Publisher Copyright: © 2023 IOP Publishing Ltd.
Keywords
band structure, defects, DFT, half Heusler, secondary phases, thermoelectric, transport properties
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Citation
Ascrizzi, E, Casassa, S, Daga, L E, Dasmahapatra, A, Maschio, L, Karttunen, A J, Boldrini, S, Ferrario, A, Fanciulli, C, Aversano, F, Baricco, M & Castellero, A 2023, ' Experimental and computational study of the role of defects and secondary phases on the thermoelectric properties of TiNi 1+x Sn (0 ≤ x ≤ 0.12) half Heusler compounds ', Nanotechnology, vol. 34, no. 31, 315703 . https://doi.org/10.1088/1361-6528/acd120