| Autor: |
Douglas, Jason E., Birkel, Christina S., Verma, Nisha, Miller, Victoria M., Mao-Sheng Miao, Stucky, Galen D., Pollock, Tresa M., Seshadri, Ram |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 2014, Vol. 115 Issue 4, p1-11, 11p, 2 Color Photographs, 3 Black and White Photographs, 2 Charts, 9 Graphs |
| Abstrakt: |
Thermoelectric properties and phase evolution have been studied in biphasic Ti-Ni-Sn materials containing full-Heusler TiNi2Sn embedded within half-Heusler thermoelectric TiNiSn. Materials, prepared by levitation induction melting followed by annealing, were of the nominal starting composition of TiNi1+xSn, with x between 0.00 and 0.25. Phases and microstructure were determined using synchrotron X-ray diffraction and optical and electron microscopy. The full-Heusler phase is observed to be semi-coherent with the half-Heusler majority phase. Differential thermal analysis was performed to determine melting temperatures of the end-member compounds. The thermal conductivity is reduced with the introduction of a dispersed, full-Heusler phase within the half-Heusler material. This leads to an increased thermoelectric figure of merit, ZT, from 0.35 for the stoichiometric compound to 0.44 for TiNi1.15Sn. Beyond x=0.15 ZT decreases due to a rise in thermal conductivity. Density functional theory calculations using hybrid functionals were performed to determine band alignments between the half- and full-Heusler compounds, as well as comparative energies of formation. The hybrid functional band structure of TiNiSn is presented as well. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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