Crystal structure investigation of spinel-type LiAlON with multiple atomic disorders

Spinel-type lithium aluminum oxynitride (LiAlON) contains atomic disorders at every crystallographic position, including vacancies, cation, and anion disorders. In this work, the crystal structure of spinel-type LiAlON with multiple atomic disorders was systematically studied by first-principles calculation, solid-state NMR, and the Rietveld crystal structure refinement. The theoretical simulations demonstrate that the Li+ occupies octahedral positions and prefers to be far away from the N3- and cation vacancies in the crystal structure of LiAlON. A spinel-type LiAlON compound with chemical formula of Li0.06Al2.72O3.77N0.23 was prepared by solid-state reaction. The local structure of Li+ and Al3+ was probed by Li-7 and Al-27 solid-state NMR technology. Combined with theoretical calculations and solid-state NMR, the crystal structure of Li0.06Al2.72O3.77N0.23 was fully resolved by the Rietveld refinement. This work provides a deep understanding on the disordered crystal structure of the spinel-type LiAlON solid solution.