Idiochromatic blue cobalt aluminate (CoAl2O4) and purple pyroborate Co2B2O5 were prepared by solution combustion method using corresponding metal nitrates, boric acid and carbohydrazide mixtures. Allochromatic Co2+ doped in Al2O3/ZnAl2O4 and Mg2B2O5 pigments having the same colour intensity as idiochromatic pigments were obtained similarly. All the pigments are voluminous, homogeneously coloured with a large surface area. The products are characterized by their characteristic colours, XRD, IR and electronic spectra.
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