Yttrium-doped barium zirconate is known for its good oxygen ion conductivity and excellent proton conductivity. Since a full hydration is selfdom achieved in practice, the partially hydrated material contains a significant residual fraction of oxygen vacancies which enable oxygen ion migration through a classical vacancy hopping mechanism. Effectively, this renders the material a mixed ionic conductor, with both protons and oxygen ions being mobile. Yet, the oxygen transport is often neglected since oxygen ions are expected to be far less mobile than protons within these materials. In this contribution, a combination of density functional theory calculations and kinetic Monte Carlo ensemble simulations is applied to investigate the influence of vehicle migration on the oxygen ion transport in yttrium-doped barium zirconate assuming the corporate migration of OH⁻ species. The first-principles energy calculations suggest substantially reduced migration barriers in comparison to isolated O²⁻ migration and the subsequent Monte Carlo simulations indicate an increase of the oxygen ion conductivity due to the concerted migrations, while the proton movement remains almost unaffected. Surprisingly, the inclusion of vehicle movement does not increase the oxygen ion transport directly but seems to enable oxygen vacancies trapped at yttrium defects to leave trapping regions. This greatly improves the total oxygen ion mobility in the system by classical vacancy hopping, while the direct contribution of the OH⁻ hopping to the oxygen ion conductivity seems to be detrimental.

中文翻译：

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钇掺杂锆酸钡中 OH− 载体迁移的从头算研究


掺钇锆酸钡以其良好的氧离子传导性和优异的质子传导性而闻名。由于在实践中完全水合是自行实现的，因此部分水合的材料含有大量残留的氧空位，这使得氧离子能够通过经典的空位跳跃机制迁移。实际上，这使得该材料成为混合离子导体，质子和氧离子都可以移动。然而，氧传输经常被忽视，因为氧离子在这些材料中的移动性远低于质子。在本文中，假设 OH ^-物质共同迁移，结合密度泛函理论计算和动力学蒙特卡罗系综模拟，研究车辆迁移对钇掺杂锆酸钡中氧离子输运的影响。第一原理能量计算表明，与孤立的 O ²⁻迁移相比，迁移势垒大大降低，随后的蒙特卡罗模拟表明，由于协同迁移，氧离子电导率增加，而质子运动几乎不受影响。令人惊讶的是，车辆运动的加入并没有直接增加氧离子传输，但似乎使得钇缺陷处捕获的氧空位能够离开捕获区域。这通过经典的空位跳跃极大地提高了系统中的总氧离子迁移率，而^OH-跳跃对氧离子电导率的直接贡献似乎是有害的。