Complex Cation (dis-)Order in Sodium Perovskites for Battery Applications

The cost, geographical distribution and relative scarcity of lithium reserves has led us to search for sodium-based battery materials in a new compositional series Na1.5Ln1.5TeO6. These display a range of unusual Na+ environments that facilitate fast Na+ conduction. The property makes these structures candidates for use in Na-based batteries. Our current understanding of the ion transport is limited by analysis of X-ray diffraction data and electron microscopy, which are both insensitive to the Na and oxide positions giving only a partial picture of the crystal structures. All these compounds form variations on the perovskite structure displaing cation (dis)order or other superstructures. Neutron diffraction is vital to build a complete picture of the cation coordination, cation ordering and oxide displacements that facilitate Na migration in these new materials.