Electron paramagnetic resonance (EPR) and X-ray absorption fine structure measurements were combined with first principles calculations to investigate the substitutional behavior of Mn ions in perovskite CaTiO₃ ceramics. While transition-metal dopants in perovskite-structured oxides often act as aliovalent defects, Mn in CaTiO₃ is amphoteric and concurrently occupies both Ca and Ti sites as Mn²⁺ and Mn⁴⁺, respectively. Contrary to the behavior of Mn in SrTiO₃ and BaTiO₃, which exhibit larger geometric perovskite tolerance factors, in CaTiO₃, it is determined that Mn²⁺ prefers A-site substitution. Density functional theory (DFT) calculations provide insight to the unique defect chemistry of Mn-doped CaTiO₃ compared to SrTiO₃ and BaTiO₃, highlighting the role of octahedral rotations which accommodate ionic size mismatch between the larger host and smaller dopant cations on the cuboctahedral sites without significant dopant-ion displacements. Superposition models of the EPR zero-field splitting parameters for multiple types of Mn defect centers were considered based on the structural parameters of DFT calculations, and these results, combined with the EPR, DFT, and X-ray absorption analysis, were used to determine the point defect substitution mechanisms of Mn-CaTiO₃.

将电子顺磁共振（EPR）和X射线吸收精细结构测量与第一性原理计算相结合，以研究钙钛矿CaTiO ₃陶瓷中Mn离子的取代行为。尽管钙钛矿结构氧化物中的过渡金属掺杂剂通常是铝同价缺陷，但CaTiO _3中的Mn是两性的，并且同时占据Ca和Ti的两个位置，分别为Mn ²⁺和Mn ⁴⁺。与表现出较大几何钙钛矿容忍因子的SrTiO ₃和BaTiO _3中的Mn行为相反，在CaTiO _3中，确定了Mn ²⁺倾向于A站点替代。密度泛函理论（DFT）计算提供了与SrTiO ₃和BaTiO ₃相比，Mn掺杂的CaTiO ₃独特的缺陷化学的见解，突出了八面体旋转的作用，适应了八面体上较大的主体和较小的掺杂阳离子之间的离子尺寸失配。没有明显的掺杂离子位移的位点。基于DFT计算的结构参数，考虑了多种类型的Mn缺陷中心的EPR零场分裂参数的叠加模型，并将这些结果与EPR，DFT和X射线吸收分析相结合来确定Mn-CaTiO ₃的点缺陷替代机理。