Thermoanalytical study of iron(III) phosphate obtained by homogeneous precipitation from different media

Amorphous iron(III) phosphate has been synthesised by homogeneous precipitation from equimolecular Fe(NH4)2(SO4)2·6H2O and NH4H2PO4 aqueous, water–ethanol and water–iso-propanol solutions at pH=2.0 and ambient temperature using hydrogen peroxide as precipitating agent. The precipitates have been characterised by TG/DTG/DTA techniques, chemical analysis, X-ray powder diffraction (XRD) analysis and scanning electron microscopy (SEM). The presence of ethanol and iso-propanol in the precipitation medium suppressed the co-precipitation of ferric sulphate as it does in aqueous medium. Thermal treatment of the as-precipitates at 750 °C in air yields a crystalline quartz-like structured FePO4 with markedly different morphological features.