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 degrees 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 degrees C for 1 h in air.