Formation of LaFeO3 and thermal decomposition reactions in lanthanum(III) oxalate-iron(II) oxalate crystalline mixture

摘要

Thermal processes involved during the decomposition course of La-2(C2O4)(3)center dot 10H(2)O-FeC2O4 center dot 2H(2)O (1:2 mole ratio) mixture up to 750 degrees C, in an atmosphere of air, were monitored by thermogravimetry and differential thermal analysis. X-ray diffraction and Mossbauer spectroscopy were used to characterize the intermediates and the final product. The results showed that a microcrystalline or possibly amorphous iron(III) oxide with a paramagnetic nature was appeared in the early stages of decomposition at 250 degrees C. By increasing the temperature, a well crystalline hematite with ferromagnetic properties was obtained. XRD pattern of the mixture calcined at 1100 degrees C shows the formation of LaFeO3 single phase in consistent with the hyperfine magnetic splitting (one sextet of lines) characteristic of LaFeO3 obtained in the Mossbauer spectra of the mixture calcined at the same temperature.