Cobalt chromite nano pigments synthesis through microwave-assisted polyol route

In this study, cobalt chromite (CoCr₂O₄) nano pigments were synthesized in a microwave oven at 180 °C for 2 h by using corresponding metal acetates in diethylene glycol media. The resulting powders (as-synthesized and calcined) were successfully characterized by X-ray diffraction, thermogravimetry–differential scanning calorimetry, fourier transform infrared, field emission scanning electron microscopy and dynamic light scattering method. Results show that the as-prepared powders consist of amorphous compound with 30 nm average particle size. Upon calcination of this product, CoCr₂O₄ spinel phase starts forming at 400 °C and stable spinel phase formation was completed at 700 °C. The pigment calcined at 700 °C for 3 h showed blue-green hue by ultraviolet-visible spectra. In addition, the particle size distribution remained nano size even after calcination.