We investigated the electronic and thermoelectric properties of half-Heusler alloys NiTZ (T = Sc and Ti; Z = P, As, Sn, and Sb) having an 18 valence electron count. Calculations were performed by means of density functional theory and the Boltzmann transport equation with constant relaxation time approximation, validated by NiTiSn. The chosen half-Heuslers were found to be indirect bandgap semiconductors, and the lattice thermal conductivity was comparable with the state-of-the-art thermoelectric materials. The estimated power factor for NiScP, NiScAs, and NiScSb revealed that their thermoelectric performance can be enhanced by an appropriate doping rate. The value of ZT found for NiScP, NiScAs, and NiScSb is 0.46, 0.35, and 0.29, respectively, at 1200 K.

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Thermoelectric phenomena provides an alternative for power generation and refrigeration which can be the best solution to the energy crisis by utilizing waste heat energy in the near future. In...

On the basis of density functional theory and semi-classical Boltzmann theory, we have investigated the structural, elastic, electronic, optical and thermoelectric properties of 18-valence electron count rhodium based half-Heusler alloys focusing on RhTiP, RhTiAs, RhTiSb, and RhTiBi. The absence of imaginary frequencies in the phonon dispersion curve for these system verifies that they are structurally stable. RhTiP is ductile in nature, while others are brittle. The alloys are found to be semiconducting with indirect band gaps ranging from 0.94 to 1.01 eV. Our calculations suggest these materials to have high absorption coefficient and optical conductivity in the ultraviolet as well as visible region. While considering thermoelectricity, we found that p-type doping is more favorable in improving the thermoelectric properties. The calculated values of power factor with p-type doping are comparable to some of the reported half-Heusler materials. The optimum figure of merit ZT is ∼ 1 for RhTiBi suggesting it as a promising candidate for thermoelectric applications while RhTiP, RhTiAs, and RhTiSb with optimum ZT values between 0.38 to 0.67 are possible candidates for use in thermoelectric devices.

Computational details Structure Optimization Results and discussionsElectronic properties Thermolectric properties Conclusions 3/16