There is growing interest to discover suitable calcium containing oxides that can be used as electrode materials in calcium ion batteries. A comprehensive computational investigation of ionic defects and Ca-ion diffusion in Ca-bearing oxide materials at the atomic level is important so as to predict their suitability for use in Ca-ion batteries. In this study, we apply atomistic simulation techniques to examine the energetics of defects, dopants, and Ca-ion diffusion in Ca₃Fe₂Si₃O₁₂. The calculations suggest that the Ca/Fe anti-site defect is the most favorable intrinsic defect causing such significant disorder, which would be sensitive to synthesis conditions. Diffusion of Ca²⁺ ions within Ca₃Fe₂Si₃O₁₂ is three-dimensional, with the activation energy of migration of 2.63 eV inferring slow ionic conductivity. The most favorable isovalent defects are Mn²⁺, Sc³⁺, and Ge⁴⁺ on Ca, Fe, and Si, respectively, for this process. The formation of extra calcium was considered to increase the capacity and diffusion of Ca in this material. It is found that Al³⁺ and Mn²⁺ are the candidate dopants on the Si and Fe sites, respectively, for this process and there is a reduction observed in the activation energies. The electronic structures of favorable dopant configurations are discussed using density functional theory simulations.

中文翻译：

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石榴石Ca3Fe2Si3O12的缺陷，迁移和掺杂性质

发现合适的含钙氧化物可用作钙离子电池中的电极材料的兴趣日益浓厚。在原子水平上对含钙氧化物材料中的离子缺陷和Ca离子扩散进行全面的计算研究非常重要，以便预测它们在Ca离子电池中的适用性。在这项研究中，我们应用原子模拟技术来检查Ca ₃ Fe ₂ Si ₃ O _12中的缺陷，掺杂剂和Ca离子扩散的能级。计算表明，Ca / Fe抗位缺陷是引起这种显着紊乱的最有利的内在缺陷，对合成条件很敏感。Ca ₃内Ca ²⁺离子的扩散Fe ₂ Si ₃ O ₁₂是三维的，迁移能量为2.63 eV，表明离子电导率较低。对于此过程，最有利的等价缺陷分别是Ca，Fe和Si上的Mn 2 ⁺，Sc ³⁺和Ge ⁴⁺。多余钙的形成被认为可以增加Ca在这种材料中的容量和扩散。发现对于该过程，Al ³⁺和Mn ²⁺分别是Si和Fe位点上的候选掺杂剂，并且观察到活化能降低。使用密度泛函理论模拟讨论了有利的掺杂剂结构的电子结构。