The effect of temperature on the crystallization of α-Fe2O3 particles from dense β-FeOOH suspensions

The effect of temperature on the crystallization of α-Fe2O3 particles from dense β-FeOOH suspensions was monitored by 57Fe Mössbauer spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and energy dispersive spectroscopy. Dense suspensions of very long laterally arranged β-FeOOH fibrils were obtained at 90 °C. Crystallization at 120 °C between 18 and 72 h yielded monodisperse α-Fe2O3 particles of a shape close to that of double spheres with ring. The double spheres with ring showed two narrow particle size distributions. In these particles a substructure was detected, i.e., the spheres consisted of the linear chains of interconnected α-Fe2O3 subparticles. With further rise in the crystallization temperature the increase in α-Fe2O3 particles and porosity became pronounced. Obviously, the aggregation mechanism played an important role in the formation of α-Fe2O3 particles.