Half-Heusler TiXSn (X=Pd, Pt and Ni): electronic, vibrational, and defect properties from first-principles calculations
| Autor: | Lopes, Mateus Corradini, Antonelli, Alex |
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| Rok vydání: | 2023 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | The knowledge of Half-Heusler compounds have attracted much attention as materials for thermoelectric applications. In this work, we investigate, using first-principles calculations, the electronic, vibrational, and defect properties of TiXSn (X=Ni, Pd, Pt) half-Heusler compounds. The knowledge of such properties is vital for the understanding and improvement of thermoelectric transport properties of these materials. The band gap of the three compounds increase with the atomic number of the group 10 elements, in agreement with previous findings. The electronic effective masses of the three compounds are similar, while the heavy hole effective mass of TiPtSn is larger than those of the other two materials. Our calculations of the phonon dispersion included the calculation of the LO-TO splitting indicating that TiNiSn has a stronger ionic character and polar scattering of charge carriers by optical phonons in the case of low doping. Calculation of the formation energy of Ni interstitial defect in TiNiSn is very low, in agreement with previous results. Surprisingly, for the Pd interstitial in TiPdSn the formation energy is negative, suggesting that the full-Heusler structure can be more stable than the half-Heusler one. On the other hand, the formation energy of an interstitial in TiPtSn is significantly higher, suggesting smaller effects on both electronic structure and transport properties. The formation energy of all substitutional defects investigated are substantially higher than that of interstitial ones, suggesting that they should occur in very low concentrations. Comment: 7 pages, 7 figures |
| Databáze: | arXiv |
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