Synthesis and Characterization of CoAl2O4 Nano Pigments by Polyol Method

Blue nano pigments of CoAl2O4 were successfully prepared by polyol method. Two different groups of materials containing chloride and acetate compounds were used to synthesis the nano pigments. The nano pigments were calcinated at 1100 °C. The CoAl2O4 nano pigments were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), dynamic light scattering (DLS), UV–Vis spectroscopy and CIE-L*a*b* colorimetric measurement. Dynamic light scattering analysis confirmed the formation of nanoparticles in the suspensions. XRD data of CoAl2O4 powders shows the acetate compounds resulted in a mono-phase CoAl2O4 spinel structure, while the chloride compounds resulted in two phases of CoAl2O4 and Al2O3 crystal structures. The SEM images showed that the average size of nano CoAl2O4 pigments is about 50 nm for all nano pigments while they have some agglomerations. The formation of blue pigments in all samples was confirmed by means of colorimetric parameters and DRS spectra. The purity and intensity of color for the samples were different.