制备方法对LaFeO_3纳米粉体的影响

Effect of Synthesis Method on Synthesis of LaFeO_3 Nanopowders

分别采用熔盐法和溶液燃烧法合成了钙钛矿型LaFeO3纳米粉体,系统研究了两种制备方法对粉体相结构、形貌的影响,用XRD、SEM和TG/DSC对纳米粉体进行了表征。结果表明:熔盐体系、煅烧温度、燃料类型和燃料/氧化剂的摩尔比对合成LaFeO3有重要的影响。450-750℃的熔盐NaNO2体系及650-800℃的熔盐NaNO3–KNO3体系分别反应2h,均可合成单一的LaFeO3纳米晶体。乙二醇为燃料,富燃时(+40%)LaFeO3晶型最好,产物为蓬松的多孔网状纳米结构,晶粒尺寸为28.0 nm;而甘氨酸为燃料,在燃料/氧化剂比为化学计量比时可得到19.0 nm LaFeO3纳米粉体。

Perovskite type of compound LaFeO3 nanopowders were successfully prepared by both molten salt and solution combustion methods.The effects of the two methods on phase composition and morphology of products were studied systematically.The products were characterized by XRD,SEM and TG/DSC techniques.The results showed that the type of molten salt,annealing temperature,fuel type and fuel-to-oxidant ratio play an important role in the synthesis of LaFeO3,LaFeO3 nanocrystals were successfully synthesized in molten NaNO2 at 450-750℃ and molten NaNO3–KNO3 at 650-800℃ for 2 h,respectively.When glycol was used as fuel,net-like porous LaFeO3 powders with a crystallite size of 28.0 nm were obtained in the fuel-rich condition（＋40%）.While LaFeO3 nanocrystals with a crystallite size of 19.0 nm were obtained with glycine in stoichiometric fuel-to-oxidant ratio.