Preparation and characterization of spinel MCr2O4 (M = Zn, Co, Cu and Ni) by combustion reaction

The ceramic industry applies many natural and synthetic pigments as coloring agents in glasses. enamels and unglazed bodies. The purpose of the present work was to prepare a series of chromium spinels MCr2O4 (M = Zn, Co, Cu and Ni) by combustion reaction, using urea as fuel and characterizing the resulting powders. The compositions were prepared by a single step solution combustion reaction using nitrates and urea as fuel. The fired pigments and enameled samples were characterized by X-ray diffraction, BET, scanning electron microscopy (SEM), UV-VIS-NIR spectroscopy, and CIE-L*a*b* color-measurements. The results demonstrated that synthesis by the combustion reaction was very fast and safe, resulting in crystalline spinel with nanoparticles in all the compositions under study. The pigments obtained by combustion reaction displayed better solubility in the molten glazes than pigments obtained by mechanical mixture of oxide precursors. The results demonstrate the viability of using the powders obtained as ceramic pigments.