Mn3−xZnxO4 spinel phases in the Zn–Mn–O system

The thermal evolution of the Zn–Mn–O system in air was studied by X-ray diffraction, transmission electron microscopy–energy dispersive spectroscopy and electron energy loss spectroscopy. The obtained results suggest that this evolution involves the formation of different Mn3−xZnxO4 spinel-type phases. With increasing temperature these spinels experience phase transformations which are found to be induced by the Mn(IV) to Mn(III) reduction process. This last cation is an active Jahn–Teller ion which leads to an appreciable distortion of the Mn3−xZnxO4 spinel structure, from a cubic symmetry at low temperatures to highly distorted tetragonal symmetries at high temperatures.