Novel TiPdC Half-Heusler Alloys with High Thermoelectric Performance for High-Grade Waste Heat Energy Harvesting

n-type beta-TiPdC (TPC) half-Heusler (HH) alloys recover waste at high-temperature heat energy from industries, thermal energy plants, and nuclear energy plants. Therefore, this article thoroughly investigates the structural, mechanical, electronic, and thermoelectric properties of novel polymorphic HH TPC alloys using density functional theory and Boltzmann transport theory. The optimal structural parameters are obtained from the energy-volume curves. Negative formation energy (EForm) and formation enthalpy (Delta H) demonstrate that these alloys can be prepared experimentally. Excellent ductility and hardness, i.e., mechanical stability is verified by Born-Huang stability criteria. Semimetallic (alpha, beta) and semiconducting (gamma, Eg = 0.99 eV) behaviors are established from their band structure and density of states. n-type beta-TPC exhibits the highest figure of merit (ZT = 0.79) at 1000 K for its high-power factor (PF) and low total thermal conductivity (Kt). High PF is reflected by the effective mass effect, high Seebeck coefficient (S), electrical conductivity (sigma), and band alignment that lead to low Kt.