PHASE-TRANSFORMATION OF FEC2O4-CENTER-DOT-2H(2)O HEAT-TREATED IN H-2 NH3/

The phase transformation of FeC2O4 . 2H(2)O heat treated in H-2/NH3 is studied with differential scanning calorimetry (DSC), X-ray diffracti on (XRD) and Mossbauer spectroscopy. The results indicate that the deh ydration of the precursor and the decomposition of FeC2O4 take place a t the same time, but their reaction rates are different at the same te mperature. The initial solid products of the decomposition are Fe1-xO and superparamagnetic Fe3O4. During the growth of Fe1-xO and Fe3O4, Fe 1-xO changes to Fe3O4 and alpha-Fe. With increasing temperature, the r eduction and nitridation processes tend gradually towards simultaneous ness, and the phase transition of nitrides takes place. If the heat tr eating temperature is higher,such as 750 degrees C, the content of nit rogen in the sample decreases and the alpha-Fe phase is reproduced fro m nitrides.