Effect of the substitution of Co2+ by Mg2+ on the color of the CoCr2O4 ceramic pigment synthesized by solution combustion

This research presents the effect on the color of the green ceramic pigment CoCr2O4 when Co2+ was replaced by Mg2+. The objective is to reduce the concentration of cobalt in the pigments, which is considered an expensive and toxic raw material. The pigments were synthesized by solution combustion in one-step. The X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) of the as-prepared powders showed that the spinel structure was obtained during the combustion reaction. The microstructure of the pigments was observed by Scanning Electron Microscopy (SEM) and the powders are porous due to the gases formed during the reaction. Finally, the color change of the powders was evidenced by UV-vis-NIR Diffuse Reflectance Spectroscopy (DRS) and calculation of CIEL*a*b* chromatic coordinates. The largest color change Delta E*(ab) of 9.8 was between CoCr2O4 and MgCr2O4 as a result of the absence of electronic transitions in Mg2+. The results of thermal stability of the green pigments using a commercial frit showed that they could be used in ceramic decoration at 1050 degrees C. (C) 2019 SECV. Published by Elsevier Espana, S.L.U. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).