Nanocrystalline LaFeO3 preparation and thermal process of precursor

Nanocrystalline LaFeO3 was synthesized by calcining precursor La2(CO3)2(OH)2–Fe2O3⋅1.5H2O in air. XRD analysis showed that precursor dried at 80 °C was a mixture containing orthorhombic La2(CO3)2(OH)2 and amorphous Fe2O3⋅1.5H2O. Orthorhombic LaFeO3 with highly crystallization was obtained when La2(CO3)2(OH)2–Fe2O3⋅1.5H2O was calcined at 900 °C in air for 2 h. Magnetic characterization indicated that the calcined product at 900 °C behaved weak magnetic behavior at room temperature. The thermal process of La2(CO3)2(OH)2–Fe2O3⋅1.5H2O experienced five steps, which involves, at first, dehydration of 0.8 absorption water, then dehydration of 0.7 crystal water, decomposition of orthorhombic La2(CO3)2(OH)2 into orthorhombic LaCO3OH, reaction of two LaCO3OH into hexagonal La2O2CO3 and crystallization of tetragonal Fe2O3, at last, reaction of hexagonal La2O2CO3 with tetragonal Fe2O3 into orthorhombic LaFeO3. In the DTG curve, four DTG peaks indicated the precursor experienced mass loss of four steps.