水化Y掺杂BaZrO $_3$的局域畸变和动力学
Local distortions and dynamics in hydrated Y-doped BaZrO$_3$
摘要：
钇掺杂BaZrO $_3$是一种很有前途的中温固体氧化物燃料电池质子导体。在这项工作中，结合静态DFT计算和基于DFT的分子动力学（DFT-MD）来研究质子在这种材料中的传导。100个掺杂浓度为12.5%的结构的几何优化使我们能够识别出金属-氧-金属角的弯曲与模拟电池的能量之间的明确相关性。根据弯曲的类型，定义了两种配置，指定为向内弯曲和向外弯曲。结果表明，较大的弯曲降低能量，并且观察到向内弯曲与靠近掺杂剂原子的质子相结合的结构的最低能量。这些能量最低的结构是具有最强氢键的结构。在具有不同钇分布的细胞中的DFT-MD模拟提供了关于质子扩散的补充微观信息，因为它们捕获了由热运动引起的晶格的动态扭曲。对不同环境之间质子跳跃的仔细分析证实，向内和向外弯曲状态与理解质子扩散有关。事实上，八面体内的跳跃只发生在向外的构型，而向内的构型似乎有利于围绕氧的旋转。平均而言，在DFT-MD模拟中，向外构型的氢键长度较短，这有利于八面体内跳跃。扩散系数和活化能也被确定和以前的理论和实验数据相比，显示出良好的协议与以前的数据对应的本地质子运动。
英文摘要：
Y-doped BaZrO$_3$ is a promising proton conductor for intermediate temperature solid oxide fuel cells. In this work, a combination of static DFT calculations and DFT based molecular dynamics (DFT-MD) was used to study proton conduction in such a material. Geometry optimisations of 100 structures with a 12.5% dopant concentration allowed us to identify a clear correlation between the bending of the metal-oxygen-metal angle and the energies of the simulated cells. Depending on the type of bending, two configurations, designated as inwards bending and outwards bending, were defined. The results demonstrate that a larger bending decreases the energy and that the lowest energies are observed for structures combining inwards bending with protons being close to the dopant atoms. These lowest energy structures are the ones with the strongest hydrogen bonds. DFT-MD simulations in cells with different yttrium distributions provide complementary microscopic information on proton diffusion as they capture the dynamic distortions of the lattice caused by thermal motion. A careful analysis of the proton jumps between different environments confirmed that the inwards and outwards bending states are relevant for the understanding of proton diffusion. Indeed, intra-octahedral jumps were shown to only occur starting from an outwards configuration while the inwards configuration seems to favor rotations around the oxygen. On average, in the DFT-MD simulations, the hydrogen bond lengths are shorter for the outwards configuration which facilitates the intraoctahedral jumps. Diffusion coefficients and activation energies were also determined and compared to previous theoretical and experimental data showing a good agreement with previous data corresponding to local proton motion.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
