Hydrothermal synthesis of flake-like MnCO3 film under high gravity field and their thermal conversion to hierarchical Mn3O4

A flake-like MnCO₃ film has been successfully synthesised by the hydrothermal method, with high gravity field using 0.5 mol/L MnCl₂ and 5 mol/L CO(NH)₂ as precursor at 120°C for 30°min in the aqueous solution°bromobenzene system. The effects of the relative centrifugal field and the reaction temperature on the formation of flake-like MnCO₃ film were examined. The resultant samples were characterised by X-ray diffraction, Fourier transform infrared, FE-scanning electron microscopy and thermogravimetric differential thermal analysis. The results reveal that low temperature and high gravity field are favourable for the formation of flake-like MnCO₃ film. The hierarchical Mn₃O₄ were obtained after calcinations of the flake-like MnCO₃ film at 700°C for 1°h in air.