Effect of Decomposition Temperature on the Crystallinity of α-Fe 2 O 3 (Hematite) Obtained from an Iron(III)-Hexamethylenetetramine Precursor

Abstract

Iron(III) oxides has often been synthesized by techniques that require expensive equipment, extra purification steps and long reaction times. For practical applications, methods that use readily available, cost-effective and non-toxic precursors should be employed. Nanoparticles of α-Fe2O3 were synthesized by thermal decomposition of a precursor prepared from hexamethylenetetramine (HMTA) and iron(III) nitrate in an ethanol/water mixture. The precursor, (Fe(HMTA)2(H2O)3(NO3))(NO3)2·2H2O, was characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), and thermal gravimetric analysis. It was calcined at 300, 400 and 500oC for 2 h, and the iron oxide obtained was characterized by X-ray diffraction (XRD), FTIR, scanning electron microscopy, high resolution transmission electron microscopy and nitrogen physisorption. XRD shows that the α-Fe2O3 obtained changed from amorphous to crystalline with variation in calcination temperature. The particles tend to form a gel-like porous matrix. Our approach uses simple and cheap precursors, which should make it suitable for large-scale synthesis.