Preparation of cadmium chromite spinel: a combustion approach

The effect of preparation precursors as well as the presence and/or the absence of a combustion fuel, viz. urea, on the texture of Cd-Cr-O system was investigated. The phase changes accompanying the thermal treatment of three CdCr-O parents were monitored using thermogravimetry, differential scanning calorimetry, X-ray diffractometry and Fourier transform infrared spectroscopy. Moreover, the surface excess charge, Cr6+ ions, was determined spectrophotometrically. The textural features were assessed via the analysis of nitrogen sorption isotherms. The present results revealed that the presence of chromia gel, as one of the precursors, together with the burning fuel is responsible for the high surface areas measured. In addition, the presence of urea favours the formation of cadmium chromite spine at low temperatures as such as 250 degreesC. Finally, a trail was made to check the effect of the removal of water-leached Cr6+ ions on the textural properties of the prepared solids. (C) 2002 Elsevier Science B.V. All rights reserved.