Solution Combustion Synthesis of (Co,Fe)Cr2O4 pigments

The synthesis of mixed cobalt–iron chromites, Fe1−ΨCoΨCr2O4 (0 ≤ Ψ ≤ 1), has been studied by Solution Combustion Synthesis using urea as fuel. Characterization by XRD and SEM showed that crystallinity, cell parameters, crystallite size and grain size depend on Ψ. The higher is the cobalt content of the initial composition the greater are these four characteristics, but evolution of cell parameters, crystallite size and grain size is not regular, since the variations are more pronounced for the spinels with high iron content. Apparently, the method causes some deficiency in the oxygen content of the spinels and a slight enrichment in chromium with respect to the theoretical composition, but does not alter the proportions of iron and cobalt. All synthesized chromites showed a high tinting strength in ceramic glazes without any additional annealing step