Study on La Doping Modification and Transport Characteristics of Indium Oxide-Based Thermoelectric Materials for Waste-Heat Power Generation Application

To address the trade-off between thermoelectric efficiency in oxide thermoelectric materials used in Aiye Processing Equipment, this study investigates the effect of La doping on the thermoelectric properties of indium oxide (In2O3) through experimental characterization and mechanism analysis. The results show that La doping induces synergistic optimization of the electronic structure, lattice dynamics, and defect state of In2O3, leading to simultaneous enhancements in thermoelectric and mechanical properties. Specifically, La3+ substitution for In3+ significantly increases carrier concentration, which, combined with the band convergence-induced elevation of density of states (DOS) near the Fermi level, results in a remarkable improvement in power factor (from the intrinsic enhancement driven by electrical conductivity) while mitigating the reduction in Seebeck coefficient. Meanwhile, lattice distortion caused by ionic radius mismatch and decreased Young’s modulus (due to weakened In-O bonds) jointly enhance phonon scattering and reduce phonon propagation velocity, leading to a significant decrease in lattice thermal conductivity and total thermal conductivity. Consequently, the thermoelectric figure of merit (ZT) of La-doped In2O3 increases from 0.055 to 0.358, a six-fold enhancement. Additionally, La doping improves Vickers hardness through three synergistic mechanisms: internal stress from lattice distortion, enhanced interatomic bonding (synergistic reinforcement of ionic and covalent bond components), and dislocation pinning by substitutional defects (La_In). This study demonstrates that La doping achieves the dual regulation of “promoting electrical transport, suppressing thermal conduction, and enhancing mechanical strength” in In2O3, breaking the traditional trade-off between thermoelectric and mechanical properties. The findings provide a feasible strategy for the performance optimization of oxide thermoelectrics and lay a foundation for their practical applications in energy conversion systems requiring high efficiency and structural reliability.