Graph analysis of proton conduction pathways in scandium-doped barium zirconate
Graph analysis of proton conduction pathways in scandium-doped barium zirconate
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DOI：
10.1063/5.0039103
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发表时间：
2021-02-21
影响因子：
4.4
通讯作者：
Khan, Samira
中科院分区：
文献类型：
--
作者：
Gomez, Maria A.;Brooks-Randall, Sophia;Khan, Samira
了解锆酸钡（BaZrO 3）中受主掺杂剂尺寸和质子传导率之间的关系对于最大化这种有前途的燃料电池材料的效率非常重要。虽然已经探索了具有较大YZr '和较小AlZr '缺陷的质子传导途径，但是还没有使用中心性测量、周期性途径搜索和动力学Monte Carlo（KMC）研究具有ScZr '（与被替换离子的尺寸相当的缺陷）的质子途径。BaSc0.125Zr0.875O3中的中心性措施突出了ScZr '的捕获区域和未掺杂平面上的分散的高中心性区域。连接的远程高中心区域被发现主要是在未掺杂的平面BaAl 0.125 Zr 0.875 O3和掺杂剂的平面BaY 0.125 Zr 0.875 O3。AlZr '和ScZr '系统中最好的长程质子传导周期性路径在掺杂剂平面之间行进，而钇掺杂的BaZrO 3的长程质子传导周期性路径保持在掺杂剂平面上。KMC轨迹在1000 K显示长程质子传导势垒为0.86 eV，0.52 eV，和0.25 eV的AlZr '，ScZr '，和YZr '系统，分别。长距离周期性传导高速公路限制势垒平均值与每个系统中最中心区域的连接性良好相关，但忽略掺杂剂周围的扩散和通过其他高中心区域的扩散。BaSc0.125Zr0.875O3显示了一个中间的整体导电势垒限制的陷阱，早期的实验和模拟表明，它可以减轻与增加氧空位浓度。
Understanding the relationship between the acceptor dopant size and proton conductivity in barium zirconate, BaZrO3, is important for maximizing efficiency in this promising fuel cell material. While proton conduction pathways with larger YZr ' and smaller AlZr ' defects have been explored, proton pathways with ScZr ', a defect of comparable size to the replaced ion, have not been investigated using centrality measures, periodic pathway searches, and kinetic Monte Carlo (KMC). Centrality measures in BaSc0.125Zr0.875O3 highlight a trapping region by ScZr ' and scattered high centrality regions on undoped planes. Connected long-range high centrality regions are found mainly in undoped planes for BaAl0.125Zr0.875O3 and in the dopant planes for BaY0.125Zr0.875O3. The best long-range proton conduction periodic pathways in AlZr ' and ScZr ' systems travel between dopant planes, while those for yttrium-doped BaZrO3 remained on dopant planes. KMC trajectories at 1000 K show long-range proton conduction barriers of 0.86 eV, 0.52 eV, and 0.25 eV for AlZr ', ScZr ', and YZr ' systems, respectively. Long-range periodic conduction highway limiting barrier averages correlate well with the connectivity of the most central regions in each system but ignore diffusion around the dopant and through other high centrality regions. BaSc0.125Zr0.875O3 shows an intermediate overall conduction barrier limited by trapping, which earlier experiments and simulations suggest that it can be mitigated with increased oxygen vacancy concentration.