Synthesis and Characterization of Co-precipitated Hematite-α-Fe2O3 Nanoparticles (AIO-NPs)

In the present work, we used a co-precipitation-calcination approach to synthesized Hematite-Fe2O3 Nanoparticles (AIO-NPs). In this technique we have taken 10 g of FeCl3∙6H2O, 150 ml of pure water was used to dissolve with stirring. After that, at room temperature, a 2 ml NH4OH solution was added drop by drop (drop rate = 1 ml min−1) to the stirring mixture. Throughout the synthesis, the pH remained at a constant one. After being continuously stirred for one hour at room temperature, the black dispersion was heated to evaporate for two hours at 80 °C to produce a brown powder. After being brought down to the room temperature, the product was then calcined for four hours at 500 °C. The as-prepared samples were subjected to calcination at various temperatures ranging from 400 °C to 800 °C. To study the structural properties in details, characterized by XRD. The lattice constant so obtained for α-Fe2O3 Nanoparticles (AIO-NPs) were a = b = 5.03421 Å and c = 13.746502 Å. The size of the particles was calculated from the XRD spectra with the help of Scherrer formula around 30 nm. Having increase in the annealing temperature phase transformation from magnetite (Fe3O4) to hematite (α-Fe2O3) is observed. The Raman study exhibited the lattice expansion and line broadening optical modes were observed. The modes observed at 217 and 490, 821 cm−1 are corresponding to A1g phonon modes corresponding to Fe–O symmetrical structure whereas the modes observed at wave numbers 278, 391 and 589 cm−1 are pointing the Eg phonon modes correspond Fe–O symmetrical bend. All these results are discussed in this paper. The morphology of hematite particle was not uniform and there was agglomeration.