Preparation and characterization of α-Fe2O3–CeO2 composite

In our previous study we attempted to see the effect of cerium doping (Ce/Fe ratio 0.015 to 0.074) on goethite matrix and conversion of doped goethite to hematite. In the present communication, nano-structured α-Fe2O3–CeO2 composite with Fe/Ce weight ratio as 1.1 has been synthesized by calcination of goethite-cerium hydroxide precursor prepared by co-precipitation method. It was observed that co-precipitation of cerium along with iron in hydroxide medium resulted in hindering the formation of crystalline order as the precursor formed showed poorly crystallized goethite and almost no crystallinity in Ce(OH)4. Calcination of the precursor at 400 °C showed the formation of hematite together with a broad peak corresponding to cerium oxide whereas at 800 °C, two distinct phases of α-Fe2O3 and CeO2 were observed. The Mössbauer spectra showed the presence of a paramagnetic component both for the precursor as well as for the sample calcined at 400 °C but on raising the calcination temperature to 800 °C, the paramagnetic component disappeared and the spectrum corresponding to pure α-Fe2O3 phase was observed. The microstructure of the product obtained by calcining at 800 °C showed rod like structure (30 to 50 nm width and 300 to 500 nm length) of α-Fe2O3 having equi-dimensional CeO2 particles on and around the surface. Besides the rods, equi-dimensional particles and agglomerates corresponding to CeO2 were also observed. The results show that co-precipitation followed by calcinations gives nanorods hematite with CeO2 particles bonded to its surface.