Impact of Interstitial Ni on the Thermoelectric Properties of the Half-Heusler TiNiSn
AbstractTiNiSn is an intensively studied half-Heusler alloy that shows great potential for waste heat recovery. Here, we report on the structures and thermoelectric properties of a series of metal-rich TiNi1+ySn compositions prepared via solid-state reactions and hot pressing. A general relation between the amount of interstitial Ni and lattice parameter is determined from neutron powder diffraction. High-resolution synchrotron X-ray powder diffraction reveals the occurrence of strain broadening upon hot pressing, which is attributed to the metastable arrangement of interstitial Ni. Hall measurements confirm that interstitial Ni causes weak n-type doping and a reduction in carrier mobility, which limits the power factor to 2.5–3 mW m−1 K−2 for these samples. The thermal conductivity was modelled within the Callaway approximation and is quantitively linked to the amount of interstitial Ni, resulting in a predicted value of 12.7 W m−1 K−1 at 323 K for stoichiometric TiNiSn. Interstitial Ni leads to a reduction of the thermal band gap and moves the peak ZT = 0.4 to lower temperatures, thus offering the possibility to engineer a broad ZT plateau. This work adds further insight into the impact of small amounts of interstitial Ni on the thermal and electrical transport of TiNiSn. View Full-Text
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Barczak, S.A.; Buckman, J.; Smith, R.I.; Baker, A.R.; Don, E.; Forbes, I.; Bos, J.-W.G. Impact of Interstitial Ni on the Thermoelectric Properties of the Half-Heusler TiNiSn. Materials 2018, 11, 536.
Barczak SA, Buckman J, Smith RI, Baker AR, Don E, Forbes I, Bos J-WG. Impact of Interstitial Ni on the Thermoelectric Properties of the Half-Heusler TiNiSn. Materials. 2018; 11(4):536.Chicago/Turabian Style
Barczak, Sonia A.; Buckman, Jim; Smith, Ronald I.; Baker, Annabelle R.; Don, Eric; Forbes, Ian; Bos, Jan-Willem G. 2018. "Impact of Interstitial Ni on the Thermoelectric Properties of the Half-Heusler TiNiSn." Materials 11, no. 4: 536.
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