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First-Principles Investigation of the Effect of M-Doped (M = Zr, Hf) TiCoSb Half-Heusler Thermoelectric Material

¹ College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai, China
² College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai, China
³ College of Fundamental Studies, Shanghai University of Engineering Science, Shanghai, China
⁴ College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai, China
⁵ College of Fundamental Studies, Shanghai University of Engineering Science, Shanghai, China

Journal of Materials Science and Chemical Engineering·Volume 03 (2015)·Pages 78–86·Published 17 December 2015·DOI10.4236/msce.2015.312012

Abstract

The M-doping (M = Zr, Hf) effects on the electronic structures and thermoelectric performance of TiCoSb were studied by first-principles calculations. The band structure analysis shows that substituting Ti with M does not change the band structures of these systems significantly. Most of the M-doped systems have a lower band gap value than that of TiCoSb; especially Ti0.5Zr0.5CoSb has the lowest energy band gap value of 0.971 eV. Besides, the amplitudes of the density of states in the region of the valence bands for M-doped systems show a similar but slightly higher value than TiCoSb. Those suggest that these compounds could have better thermoelectric performance than TiCoSb. The phonon dispersion relations show that the larger mass of Zr/Hf with respect to Ti lowers the optical modes and induces mixing with the acoustic branches. Our calculations offer a valuable insight on how to characterize complicated crystal structures of thermoelectric materials and optimize the material composition.

KeywordsHalf-Heusler CompoundThermoelectricFirst-PrinciplesElectronic Structure

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First-Principles Investigation of the Effect of M-Doped (M = Zr, Hf) TiCoSb Half-Heusler Thermoelectric Material

Abstract

References (34)