|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||Alloys and Compounds for Thermoelectric and Solar Cell Applications VI
||Ni-interstials Making Strong Influence on Thermoelectric Properties of TiNiSn Half Heuslers
||Yinglu Tang, Xiaoshuang Li, Lukas H. J. Martin, Christian Leinenbach, Toni Ivas, Shashwat Anand, Jeffrey G. Snyder, Corsin Battaglia
|On-Site Speaker (Planned)
From phase boundary mapping, we find that the TiNiSn phase is stable only in a narrow region of the Ti-Ni-Sn phase diagram. At least four invariant points associated with four three-phase regions with different Ni content are found. We characterized the thermoelectric properties of these invariant points. We demonstrate that Ni excess in TiNiSn results in a narrower Goldsmid gap, which we interpret to be due to the formation of an impurity band from interstitial Ni in the forbidden gap. The excess Ni forms interstitial and scatters both electrons and phonons, with the latter being much stronger and thus compensating the electron mobility decrease and leading to better zT. The temperature dependence of the solubility of TiNiSn is also studied, demonstrating increasing solubility as well as Ni interstitial amount as temperature increases, which could be useful for enhancing zT. A Calphad simulation was performed to model the temperature dependent solubility.
||Planned: Supplemental Proceedings volume