Enhanced ionic conductivity of rare-earth doped zirconia: Molecular dynamics simulation and solid-state synthesis

Zirconia-based solid electrolytes have low ionic conductivity at high temperatures, which limits the sensitivity of high-temperature oxygen sensors. Although doping modification can improve ionic conductivity by introducing oxygen vacancies to enhance ionic migration ability, the mechanism of rare earth doping in tetragonal zirconia remains unclear, and research efficiency is low. Herein, the effects of rare earth on the ionic conductivity of tetragonal zirconia were investigated through molecular dynamics simulation and high-temperature solid-state experiments. Simulations reveal that highest ionic conductivity was observed at a doping concentration of 4.17 mol%, and with Sc₂O₃ doping reaching 0.106 S/cm. Co-doping zirconia with 1 mol% Sc₂O₃ and 4.55 mol% Lu₂O₃ achieved a high ionic conductivity of 0.058 S/cm, increasing by 32 % compared to single Lu₂O₃ doping. Based on these computational findings, zirconia-based ceramics with an ionic conductivity of 0.054 S/cm were synthesized. The experimental results closely matched the computational predictions, validating the computational model. This study provides a computational framework for selecting rare-earth-doped zirconia solid electrolytes with high ionic conductivity.