Alluaudite phases are very attractive as both cathode and electrolyte materials for rechargeable sodium-ion batteries. In this work, the combined experimental and DFT studies have been performed to establish the diffusion mechanism in alluaudite-like compound Na₅In(MoO₄)₄. The ionic conductivity was found to reach 3.3 × 10⁻⁴ S/сm at 687 K, with an activation energy of 0.66 eV. The sodium diffusion mechanisms have been revealed from the analysis of the ²³Na NMR spectra along with the DFT estimations of Na-ion migration barriers. Our results predict that one-dimensional diffusion of sodium in the separate channels along the c-axis is accompanied by the cross-linking jumps providing two-dimensional diffusion in the bc-plane. It is clearly demonstrated that the indium deficiency favors 2D diffusion, but sharply increases the energy barrier for 1D diffusion. Comparison of our results for Na₅In(MoO₄)₄ and related Na₅Sc(MoO₄)₄ shows that the type and deficiency of M-metal in the Na_xM_y(MoO₄)_z alluaudites can control the sodium diffusion. The present work highlights the key aspects of cation influence on the diffusion properties in alluaudite materials.

作为可充电钠离子电池的阴极材料和电解质材料，钙铝石相非常有吸引力。在这项工作中，已进行了组合的实验研究和DFT研究，以建立在变石样化合物Na ₅ In（MoO ₄）_4中的扩散机理。的离子导电性，发现，达到3.3×10 ^{- 4}  S /сm在687 K，用0.66电子伏特的激活能。通过对²³ Na NMR光谱的分析以及对Na离子迁移势垒的DFT估算，揭示了钠扩散机理。我们的研究结果预测钠的该一维扩散在沿着这些单独通道Ç轴伴随着交联跃迁，在bc平面内提供了二维扩散。清楚地表明，铟缺乏有利于2D扩散，但会大大增加1D扩散的能垒。我们对Na ₅ In（MoO ₄）₄和相关Na ₅ Sc（MoO ₄）_4的结果的比较表明，Na _x M _y（MoO ₄）_z脲基甲酸盐中M-金属的类型和缺乏可以控制钠扩散。本工作重点介绍了阳离子对钙铝石材料扩散性能影响的关键方面。