Asia Pacific Physics Week 2024 (APPW2024)

Monday, Nov. 4, 2024

2:50 PM - 3:30 PM Plenary Talk: Narayan Prasad Adhikari (Tribhuvan University)

Theoretical Insights on Thermoelectric Behavior of 18-Valence Electron Half-Heusler XFeTe (X=Ti, Hf) and TiXPb (X=Ni, Pd, Pt) Compounds

Narayan Prasad Adhikari1 , Prakash Khatri1, 2, and Prasenjit Ghosh3,4 

1 Central Department of Physics, Tribhuvan University, Kirtipur, Kathmandu, 44613, Nepal

2 Department of Physics, Tribhuvan University, Siddhanath Science Campus, Mahendranagar, 10406, Nepal

3 Department of Physics, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pune, Maharashtra, 411008, India

4 Department of Chemistry, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pune, Maharashtra, 411008, India

Half-Heusler (hH) compounds provide an efficient solution to the energy crisis due to their high-temperature thermoelectric properties. The present study examines the stability, electronic, lattice dynamics, mechanical, and thermoelectric (TE) properties of hH XFeTe (X = Ti, Hf) and TiXPb (X = Ni, Pd, Pt) using Density Functional Theory (DFT) and Semi-Classical Boltzmann Transport Theory (BTE). The compounds are thermodynamically, dynamically, mechanically stable and  exhibits non-magnetic semiconducting behavior with indirect band gaps between (0.32-0.93) eV. All the compounds, except HfFeTe, are ductile. They exhibit stiffness, hardness, elastic anisotropy, and high melting points. Fermi surfaces, effective mass, and temperature-dependent relaxation time were evaluated to analyze the thermoelectric properties. XFeTe are more suitable for achieving a high power factor, while the TiXPb compounds exhibit very low lattice thermal conductivity, resulting in a zT > 1 for all compounds. Among all compounds, TiPtPb achieves a maximum zT value of 2.22 for n-type doping at a concentration of 9.46 × 1020 cm-3  at 900 K, and a zT value of 1.80 for p-type doping at a concentration of 4.51 × 1020 cm-3,  at 900 K. From a thermoelectric perspective, electrons exhibit better transport properties than holes in all the compounds.