Phase compositions and reaction models of zinc manganese oxides with different Zn/Mn ratios

This study investigated the phase compositions and reaction models of zinc manganese oxides with different Zn/Mn ratios. These oxides were synthesized through a conventional solid-state reaction, and the reaction between ZnO and MnO2 generates a ZnMn2O4-based spinel-like phase. Furthermore, a reaction model with a MnO2 core and a ZnMn2O4-based shell was proposed in this work. The ZnO particles on the surface hardly diffuses into the core because of the protection provided by the shell, thus, a ZnO second-phase was detected in ZM11 and ZM12 ceramics calcined at 1000 °C for 3 h and sintered at 1450 °C for 3 h. A single ZnMn2O4-based spinel-like phase was generated when Zn/Mn ratio was less than 1:2 or when the calcining time was prolonged to 30 h for ZM12 ceramics. [Display omitted] •Determine the dependent of phase compositions on the Zn/Mn ratios of zinc manganese oxides.•Propose the reaction model between ZnO and MnO2 raw powders.•Clarify the preparing processes for a single ZnMn2O4 spinel-like phase.