pH对溶胶–凝胶法合成CoFe_2O_4红外辐射性能的影响

Effect of pH on the Infrared Radiation Property of CoFe_2O_4 Powders Synthesized by Sol-Gel Method

以硝酸铁和硝酸钴为原料，柠檬酸为络合剂，采用溶胶-凝胶法合成具有高红外辐射性能的钴铁氧体，并考察初始混合溶液pH（pH=1、3、5、7）对CoFe2O4红外辐射性能的影响。利用FTIR、TG／DSC、XRD、SEM、BET和红外发射率测试等对CoFe2O4的形成过程、结构、形貌以及红外辐射性能进行表征。结果表明：不同pH的初始混合溶液所得干凝胶均具有自蔓延燃烧特性，经600℃煅烧后得到无杂质的尖晶石型CoFe2O4粉体。研究发现，初始混合溶液的最佳pH为5，此时样品8～14μm波段的红外发射率最高（0．92），形成以介孔为主的孔结构，比表面积为65．44m2/g。

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 CoFe204 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 8-14μm waveband, and the primary mesoporous structure was formed with the largest specific surface area of 65.44 m2/g.