Conductivities in Yttrium-Doped Barium Zirconate: A First-Principles Study

Yttrium-doped barium zirconate (BZY) has emerged as an attractive candidate for application as a proton (H+)-conducting solid electrolyte due to its high ionic conductivity and excellent chemical stability. In this study, the conductivities of BaZr(1-x)YxO3-delta (BZY, x = 0, 0.037, 0.074, 0.148, and 0.22) with different carriers were studied based on density functional theory (DFT) and experiments. The results revealed that yttrium doping can effectively reduce the energy barrier for the migration of protons and oxygen ions (O2-). When comparing the energy barriers for protons and oxygen ions, the energy barriers for proton migration were found to be lower than those for oxygen ion migration, which indicates that a proton conductor can offer the advantages of lower activation energy and, possibly, higher conductivity. An analysis of the electronic structure of the BZYs found that the top of the valence band exceeded the Fermi energy level following yttrium doping. As a result, the electron conductivity increased as the yttrium content increased. Furthermore, this study also tested the total conductivity of BaZr(1-x)YxO3-delta (BZY, x = 0.1, 0.2, 0.3, and 0.4) and found the trend of the total conductivity to be consistent with the results of the DFT calculations.