An X-ray diffraction and Mossbauer study of nano-crystalline Fe₂O₃-Cr₂O₃ solid solutions

Abstract

A series of gels with nominal composition Fe_2-xCr_xO₃ (x=0–2) was prepared at room temperature by an inorganic sol-gel route and studied by X-ray diffraction and Mossbauer spectroscopy. The gels dried at 105°C were found to be X-ray amorphous, but Mossbauer studies revealed the gels to be nano-crystalline solid-solution particles of the composition above, with super-paramagnetic properties. Further heating to 600°C gave crystalline X-ray patterns which allowed lattice parameter and crystallite size calculations to be made. It was found that lattice parameters and crystallite sizes decreased with increasing chromia content, and that at the higher chromia/iron ratios, a partially collapsed Mossbauer pattern results, indicating reductions in crystallite size and hyperfine field with increasing chromia content.