Effect of pH molar ratio of fuel to nitrates and calcination temperature on the glycine-nitrate synthesis of nano CoAl2O4

In this research, solution-based combustion synthesis is applied to prepare the spinel CoAl2O4 pigment from precursor solution of Al(NO3)3 .9H2O, Co(NO3)2 .6H2O and glycine. Effect of pH values (2.5, 7, 10.5), molar ratio of fuel to metal nitrates in the precursor solutions (1.5, 2) and subsequent calcination temperature (800, 1000, 1200 °C) on the powder characteristics are described. Gel formation, morphologies, specific surface area and colour of the powder are characterized using DTA/TG, XRD, TEM, BET and UV-Vis. The results indicate that the crystalline spinel CoAl2O4 is formed at all different Gl/(metal nitrates) molar ratios, pH and temperatures and higher temperature promote the increase of the crystallite size. According to TEM figures most of the particles calcined at 800 and 1000 °C has sizes less than 50 and 100 nm, respectively. Corresponding to results of BET experiment, specific surface area has its maximum values at pH 7 and decreases with increasing of temperature. Finally, colorability test indicates the complete stability of the synthesized powder in the glass matrix.