The influence of hydration on the thermal transport properties of yttria-doped barium zirconate

Perovskites exhibit excellent plasmonic conductivity in the mid-temperature range, and one of them, yttria-doped barium zirconate (BZY), is considered to be one of the most promising perovskite proton conductors. Molecular simulations provide an efficient method to study the thermal transport behavior of nanocrystalline materials. The effect of doping concentration on the thermal transport properties of yttria-doped barium zirconate (BZY) structures was investigated using the equilibrium molecular dynamics (EMD) method and phonon spectral energy density (SED) analysis. It was found that the thermal transport properties gradually decreased with increasing doping concentration, and for the structure introducing only doping without oxygen vacancies, the thermal conductivity was found to decrease similarly but higher than that of the structure introducing doping and containing oxygen vacancies. Comparison of phonon lifetime and group velocity revealed that oxygen vacancy defects enhance phonon scattering, thus causing a decrease in thermal transport properties, and doping decreases the thermal transport properties by weakening the simple harmonicity. The effect of different hydration levels on the thermal transport properties of BZY was investigated, and it was found that the thermal conductivity fluctuates for structures with low hydration levels, and continues to decrease as the proton defect content within the structure rises with increasing hydration levels. Comparing the phonon lifetime and group velocity, it was found that the proton defects caused a decrease in the thermal transport properties from both enhanced phonon diffusion and weakened harmonicity.