ZnO-Co ceramic pigments have been prepared by microwave-assisted gel combustion of zinc-nitrate-nitrate cobalt-citric acid precursors calcined at 700 to 1000 oC. The Combustion process has been investigated using thermal analysis and Fourier transformation infrared spectroscopy. X-ray diffraction, diffuse reflectance and scanning-transition electron microscopy was used to characterize the pigments. Results were compared with a solid state reaction. It was demonstrated that powders synthesis by combustion caused 200 oC reduction in the calcination temperature compared with the solid state reaction. The results demonstrated that the microwave-assisted combustion reaction was very simple and rapid to prepare 27-37.2 nm nanocrystalline pigments. Colorimetric results also indicated a broad reflectance band around 540 nm (green region) for all samples. It was deduced that the fuel-rich sample has more chromaticity and has a deeper green color.

Keywords: Microwave-assisted-gel combustion, ZnO-Co nano-crystalline, Pigment