Simple and Efficient Rout for Synthesis of Spinel Nanopigments

Nano-sized CoxMg1-xAl2O4 (x = 0, 0.1, 0.2, 0.4, 0.6, 0.8, and 1) inorganic pigments were synthesized via combustion method using beta-alanine, as a single and novel fuel, at 800 degrees C in open furnace. The obtained powders were characterized by means of X-ray diffraction (XRD), energy dispersive X-ray (EDX) elemental analysis, diffuse reflectance spectrum (DRS), CIE L*a*b* color measurements, and scanning electron microscope (SEM). XRD patterns show that all calcined powders have single phase cubic spinel structure. EDX analysis revealed the composition of desired spinels. The diffuse reflectance spectra of the CoxMg1-xAl2O4 (x > 0) pigments confirmed the presence of tetrahedrally coordinated Co2+ ions in the spinel lattice. The colorimetric data pointed out the formation of blue pigments (for x > 0), corresponding to highly negative values of b*, and the bluest color was produced for x = 0.8 and 1. SEM images showed nanoparticles with less than 30 nm crystallite size and flakes-like appearance of all synthesized powders.