Influence of grain size, oxygen stoichiometry, and synthesis conditions on the gamma-Fe2O3 vacancies ordering and lattice parameters

摘要

The soft chemistry method has been used to synthesize gamma-Fe2O3 nanoparticles: various synthesis temperature were applied to obtain nanometric powders with crystallite size in the 9-14 nm range. Powders were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectrophotometry, surface area measurements, and electron microscopy (TEM, SEM). It is clearly shown that these nanometric powders are very well cry stallized as indicated by XRD and IR spectra which present substructural bands attributed to vacancies ordering (P4(1)32). Based on these model materials and in the crystallite size range studied here, cell parameter appears to be not linked to, crystallite size. It rather depends both on hydroxide adsorption and chemical composition. (C) 2002 Elsevier Science. [References: 35]