High-Pressure Energy Dispersive X-Ray Diffraction Investigation of Lithium-Manganese Spinel

The formation of the tetragonal high-pressure structure, attributed to the Jahn-Teller distortion, was proved. The c/a axial ratio shows an increasing trend towards a stronger tetragonal distortion at high pressure. Rietveld refinement after the pressure relaxation demonstrates the presence of tetragonal artefacts of the high-pressure structure only for the LiMn2O4 sample compressed in hexagonal boron nitride (h-BN), whereas the sample compressed in silicone reveals the pure cubic phase. Confrontation with the result of the first angle-dispersive diamond-anvil-cell experiment is presented.