Department of Materials Science and Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi 466-8555, Japan.
Phys Chem Chem Phys. 2013 Jul 7;15(25):10494-9. doi: 10.1039/c3cp50316j. Epub 2013 May 16.
The configurations of oxygen ions and vacancies at various oxygen stoichiometries and temperatures in double perovskite oxides (GdBaCo2O(5+δ), 0 ≤ δ ≤ 1) have been determined by density functional theory (DFT) combined with Monte Carlo (MC) simulations. The MC simulations confirmed the existence of a superstructure at δ = 0.5, showing alternating linear ordering of oxygen ions and vacancies along the b-axis in the GdO layer. This structure is identical to that reported experimentally. Increasing the temperature up to 1200 K induces a phase transition manifested in the breaking of the oxygen/vacancy arrangement at around δ = 0.5. In the high-temperature phase, vacancies are distributed in the GdO and CoO2 layers, whereas there are no vacancies in the BaO layer. In addition, the characteristic linear arrangement is partly preserved even in the disordered high-temperature phase. Consequently, oxygen ions can migrate between the GdO and CoO2 layers, as reported in previous classical molecular dynamics simulation studies.
通过密度泛函理论（DFT）结合蒙特卡罗（MC）模拟，确定了双钙钛矿氧化物（GdBaCo2O（5+δ），0≤δ≤1）在不同氧化学计量比和温度下氧离子和空位的构型。MC 模拟证实了δ=0.5 时存在超结构，表明 GdO 层中氧离子和空位沿 b 轴交替线性排列。这种结构与实验报道的结构相同。升高温度至 1200 K 会引起相变，表现在大约δ=0.5 时氧/空位排列的破坏。在高温相中，空位分布在 GdO 和 CoO2 层中，而 BaO 层中没有空位。此外，即使在无序的高温相中，特征线性排列也部分保留。因此，正如先前的经典分子动力学模拟研究报道的那样，氧离子可以在 GdO 和 CoO2 层之间迁移。
