AN X-RAY-DIFFRACTION AND MOSSBAUER STUDY OF NANOCRYSTALLINE FE2O3-CR2O3 SOLID-SOLUTIONS

A series of gels with nominal composition Fe2-xCrxO3 (x = 0-2) was pre pared at room temperature by an inorganic sol-gel route and studied by X-ray diffraction and Mossbauer spectroscopy. The gels dried at 105 d egrees C were found to be X-ray amorphous, but Mossbauer studies revea led the gels to be nano-crystalline solid-solution particles of the co mposition above, with super-paramagnetic properties. Further heating t o 600 degrees C gave crystalline X-ray patterns which allowed lattice parameter and crystallite size calculations to be made. It was found t hat lattice parameters and crystallite sizes decreased with increasing chromia content, and that at the higher chromia/iron ratios, a partia lly collapsed Mossbauer pattern results, indicating reductions in crys tallite size and hyperfine field with increasing chromia content.