Abstract
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.
Highlights
In the past few decades, researchers have been focused on the investigation of multi-functional materials, which can be used in various applications such as in spintronics, optoelectronics, thermoelectrics, and so on
To check the dynamical stability, phonon spectrum calculations have been performed with a 4 ×4× 4 q− mesh in phonon Brillouin Zone (BZ), which is based on the density functional (DF) perturbation theory (DFPT) implemented in the Quantum Espresso (QE) package
We found that the acoustical phonon branches of NiScP and NiScAs extend nearly to 200 cm−1, while NiScSb and NiTiSn lie within 150 cm−1 in frequency
Summary
In the past few decades, researchers have been focused on the investigation of multi-functional materials, which can be used in various applications such as in spintronics, optoelectronics, thermoelectrics, and so on. The highly efficient TE devices (cooler, power generator, temperature sensors, and so on) can utilize a large amount of wasted thermal energy to generate electricity and vice versa.. Recent experimental and theoretical investigations on hH alloys are mainly focused on improving their thermoelectric efficiency ZT by tuning the power factor and thermal conductivity. The zero moment on Ti or Sc at the Y site and P or As or Sb at the Z site will give rise to zero moment for the Ni atom at the X site resulting in a non-magnetic system.49,50 This motivates us to explore the electronic, TE, and other related properties to confirm if these groups of materials could be suitable for TE devices The zero moment on Ti or Sc at the Y site and P or As or Sb at the Z site will give rise to zero moment for the Ni atom at the X site resulting in a non-magnetic system. This motivates us to explore the electronic, TE, and other related properties to confirm if these groups of materials could be suitable for TE devices
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