Preparation of CoAl2O4 nanoblue pigment via polyacrylamide gel method

The purpose of this study is to define the preparation of CoAl2O4 as a nano-ceramic blue pigment via the polyacrylamide gel method. The powders were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), thermo-gravimetric (TG) and differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR) and UV–visible techniques (UV–vis). Crystallized CoAl2O4 was obtained after calcination at 600 °C. The obtained powders in low temperature had a platy structure. By increasing the temperature, the layered structure was crushed into smaller pieces. The average particle size was approximately 18 nm. The UV–vis spectra presented three bands at 551, 590 and 628 nm attributed to the Co2 + spin transitions in tetrahedral sites. The results showed that a different calcination temperature causes a variation in the color and size of the particles. The temperature for obtaining blue CoAl2O4 was about 1000 °C.