微波工艺对溶胶-凝胶自蔓延燃烧法制备Ni_(1-x)Mn_xFe_2O_4晶体结构的影响

Effect of Microwave Processing on Crystal Structure of Ni_(1-x)Mn_xFe_2O_4 Synthesized by Sol-gel Self-propagating Process

以硝酸铁、硝酸镍和硝酸锰作为反应物,柠檬酸作为凝胶剂,采用溶胶-凝胶自蔓延燃烧工艺合成Ni1-xMnxFe2O4纳米粉体,并采用XRD、SEM和气敏性测试等分析方法对其物相组成、显微形貌和气敏性作了系统研究。结果表明:干凝胶在250℃自燃所得的粉体即为单相NiFe2O4尖晶石相。为消除残余碳,采用微波热处理15 min就能得到和在600℃下热处理1 h相同的相结构。但采用微波处理的样品颗粒形貌为块状,采用烧结炉处理的样品颗粒形貌类似菜花状。气敏性能测试结果表明:添加Mn2+有利于Ni1-xMnxFe2O4气敏性的提高,但微波处理不能有效改善材料的气敏性。

Single phase spinel type composite oxide Ni1-xMnxFe2O4 nanopowder were prepared by Sol-gel with self-propagating method using purity nickel nitrate,ferric nitrate,manganese nitrate and citric acid as reactants.The phase structure,morphology and gas sensing properties were characterized.The results indicated that the powders synthesized by gel self-propagating combusting at 250 ℃ was single NiFe2O4 phase.In order to eliminate carbon remnants,microwave heat treatment method was used.And the sample treated for 15 min in microwave oven has the same phase structure as the sample treated at 600 ℃ for 1 h in sinter furnace.The morphology of grain treated by microwave is block,while the grain treated by sinter furnace is like cauliflower.The gas sensitirity properties results show that adding Mn2＋ is help to enhance the gas sensitirity of Ni1-xMnxFe2O4 gas sensor,but the gas sensitirity can＇ t be improved by the microwave process availably.