Effect of pH on the Infrared Radiation Property of CoFe_2O_4 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 m2/g.