Control of atomic ordering of LiNiO2 thin films on a sapphire substrate from rock-salt to layered structure using uniaxial compression

Atomic ordering in oxide thin films influences electrical and catalytic properties of the materials. Herein, we investigated the atomic arrangement of LiNiO2 thin films on sapphire substrates treated by uniaxial compression (UAC) and annealing at 600∘C. Thin films with a rock-salt structure were grown using a pulsed laser deposition method at room temperature. We found that the as-grown thin films treated by UAC at 600∘C transformed from a rock-salt to a layered structure. The layer thickness of the later structure increased with increasing UAC pressure. UAC offers a useful tool in oxide thin film research that will contribute to development of new functional oxide materials and adjustment of the atomic ordering of cation materials.