（La,Ce,Pr,Nd）0.95（Mg,Zn,Pb,Cd,Ca,Sr,Ba）0.05F2.95 的神经网络势分子动力学模拟
Neural network potential molecular dynamics simulations of (La,Ce,Pr,Nd)0.95(Mg,Zn,Pb,Cd,Ca,Sr,Ba)0.05F2.95
AI总结：
本文利用神经网络势分子动力学模拟研究二价阳离子掺杂氟铈矿结构氟化物的 F- 离子传导，揭示掺杂离子尺寸匹配、约500 K时不同F位点扩散机制转变以及CeF3基化合物扩散系数更高的势能成因。
摘要：
以 Ce0.95Ca0.05F2.95 为代表的掺入二价阳离子的氟铈矿结构氟化物，与萤石结构化合物一样，是一类良好的 F- 离子导体。由于三个对称性不同的 F 位点之间存在复杂的相互作用，并且实验观察到 F 扩散机制在略高于室温时发生变化，因此对 F- 传导过程进行计算理解十分困难。这使得通常在远高于转变温度下进行的第一性原理分子动力学（FP-MD）模拟在分析转变点以下的行为时实际上没有用处。神经网络势（NNP）分子动力学模拟表明，当二价掺杂阳离子尺寸与三价阳离子尺寸相近时，F 扩散系数更高。在 Ce0.95Ca0.05F2.95 中，不同位点上 F 的扩散行为在大约 500 K 时发生变化，因为在此温度以下只有 F1 位点子晶格对 F 扩散有贡献，而在此温度以上，其余的 F2 和 F3 子晶格逐渐变得活跃。CeF3 基化合物比类似的 LaF3 基化合物具有更高的扩散系数，尽管后者的晶格参数更大，这一矛盾现象可能是由于与 LaF3 对应物相比，CeF3 中 Ce 和 F 的势能更浅所致。
英文摘要：
Tysonite structure fluorides doped with divalent cations, represented by Ce0.95Ca0.05F2.95, are a class of good F- ion conductors together with fluorite-structured compounds. Computational understanding of the F- conduction process is difficult because of the complicated interactions between three symmetrically distinct F sites and the experimentally observed change in the F diffusion mechanism slightly above room temperature, effectively making first principles molecular dynamics (FP-MD) simulations, which are often conducted well above the transition temperature, useless when analyzing behavior below the transition point. Neural network potential (NNP) MD simulations showed that the F diffusion coefficient is higher when the divalent dopant cation size is similar to the trivalent cation size. The diffusion behavior of F in different sites changes at roughly 500 K in Ce0.95Ca0.05F2.95 because only the F1 site sublattice contributes to F diffusion below this temperature but the remaining F2 and F3 sublattices becomes gradually active above this temperature. The paradox of higher diffusion coefficients in CeF3-based compounds than similar LaF3-based compounds even though the lattice parameters are larger in the latter may be caused by a shallower potential of Ce and F in CeF3 compared to the LaF3 counterparts.
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。
