Computational research of ionic conductance mechanism in bulk and interfaces of proton conductive oxides

采用基于密度泛函理论的理论计算方法，系统地计算了BaZrO_3的点缺陷形成行为。估算了热平衡缺陷浓度，包括缺陷缔合模型。我们的计算结果定量地揭示了化学计量比对BaZrO_3中缺陷形成行为的强烈影响。合成质子导电性BaZrO_3需要有富BA的条件。如果BaZrO_3样品的相平衡条件向相反的富锆侧转变，则掺杂对Ba位的替代抑制了水化反应。通过基于密度泛函理论和热力学的计算，成功地再现了与降温有关的水分子对氧化物空位的水合作用。结合能计算表明，在较低的温度条件下，质子主要与三价受主掺杂结合。为了提高氧化物的质子导电性，需要选择低缔合能的掺杂剂。

Theoretical calculations based on density functional theory have been systematically performed to compute the point defect formation behavior of BaZrO3. Thermal equilibrium defect concentrations are evaluated including defect association models. Our calculations have quantitatively revealed that stoichiometry strongly affects defect formation behavior in BaZrO3. Ba-rich condition is necessary for synthesizing proton conductive BaZrO3. If phase equilibrium condition of BaZrO3 samples changes to opposite Zr-rich side, hydration reaction is suppressed by dopants substituted for Ba sites. Hydration of oxide vacancy by water molecules associated with temperature decreasing is successfully reproduced by calculations based on DFT and thermodynamics. Calculations of association energy show that protons are mostly bound with trivalent acceptor dopants at lower temperature conditions. In order to improve proton conductivity in oxides, dopants showing low association energy need to be chosen.