Effect of mechanical activation on the synthesis of α-Fe₂O₃-Cr₂O₃ solid solutions

Abstract

Continuous α-Fe₂O₃-Cr₂O₃ solid solution series have been synthesized by two methods: (i) direct heating of coprecipitated hydroxides, and (ii) mechanical pre-treatment followed by heating. It is shown that mechanical treatment leads to a decrease in the preparation temperature of the solid solutions to 623 K. The formation of a continuous solid solution series by direct heating begins only at 773 K. The formation of the solid solutions was established by X-ray diffraction analysis, infrared and Mössbauer spectroscopy. The decrease in synthesis temperature of the α-Fe₂O₃-Cr₂O₃ solid solutions is attributed to activation of the samples during their mechanical treatment. The samples obtained have large specific surface areas (up to 130 m² g⁻¹).