Effect of pH on the Infrared Radiation Property of CoFe2O4 Powders Synthesized by Sol-Gel Method

Cobalt ferrite powders with excellent infrared radiation property were synthesized via the Sol-Gel method, where iron nitrate and cobalt nitrate were used as the original materials and citric acid as the chelating reagent. The effects of pH of the starting solution (pH=1, 3, 5 and 7) on the infrared radiation property of CoFe2O4 powders were examined according to the normal direction emissivity. The structure and morphology of the powders were characterized basing on FTIR, TG/DSC, XRD, SEM and BET measurements. It was found that the dried gels obtained from the starting solutions possessed the self-propagating combustion behavior. The pure spinel CoFe2O4 powders were obtained by the further treatment of sintered at 600℃ for 2 h. It was foumd that the optimum pH of the starting solution was 5. Under this condition, the highest infrared emissivity (0.92) of the sample was achieved in the 8−14 μm waveband, and the primary mesoporous structure was formed with the largest specific surface area of 65.44 m 2 /g.