【作者】 李翠环；

【导师】 冯旺军；

【作者基本信息】 兰州理工大学 ， 凝聚态物理， 2011， 硕士

【摘要】 尖晶石结构的锌铁氧体由于良好的气敏特性、光催化活性等,使得其在气敏传感器、催化剂等方面具有广泛的应用。本文以硝酸盐溶液为原料,分别使用溶胶-凝胶法和碳吸附法制备了尖晶石ZnFe₂O₄纳米颗粒,主要研究内容和结论如下:采用改进的溶胶-凝胶法制备尖晶石ZnFe₂O₄纳米颗粒。在前驱体溶液中通过加入丙烯酰胺使溶液更好的成胶,同时加入一定量的葡萄糖用以防止凝胶体在干燥过程中的塌缩。实验结果表明:使用络合剂柠檬酸、柠檬酸和EDTA、EDTA均可在500℃时得到高纯相的ZnFe₂O₄纳米颗粒,使用不同的络合剂对制得ZnFe₂O₄纳米颗粒的尺寸大小和形貌具有一定的影响。其中使用络合剂柠檬酸制得的ZnFe₂O₄纳米颗粒分散性较好,使用络合剂EDTA对ZnFe₂O₄纳米颗粒晶粒的细化具有一定的作用,但是ZnFe₂O₄纳米颗粒有一定程度的团聚现象。碳吸附法是利用活性炭的强吸附作用制备纳米材料的一种新方法。本文分析了使用碳吸附法制备ZnFe₂O₄纳米颗粒流程中各参数（活性炭的使用量、溶液的pH值和烧结温度）对ZnFe₂O₄纳米颗粒的影响,结果表明:用碳吸附法能够制备出纯度较高的尖晶石ZnFe₂O₄纳米颗粒,并得出最佳制备参数为:活性炭与金属原子的摩尔比为2:1、溶液的pH值为3、烧结温度为500℃。分析比较了溶胶-凝胶法和碳吸附法制得ZnFe₂O₄纳米颗粒的物性和磁性,结果表明:两种方法制得的ZnFe₂O₄纳米颗粒在烧结温度为500℃时,均具有较小的尺寸和良好的分散性,VSM分析显示室温下制得的ZnFe₂O₄纳米颗粒显示出超顺磁性,其中碳吸附法制得的ZnFe₂O₄纳米颗粒的磁滞回线呈现出明显的“S”形,说明碳吸附法制得的ZnFe₂O₄纳米颗粒的尺寸更小一些。更多还原

【Abstract】 Spinel zinc ferrite was widely used in gas-sensitive sensors, catalyst, for its good gas-sensitive and characteristics photocatalytic activity. In this paper, with nitrate solution as raw materials, spinel ZnFe₂O₄ nanoparticles were prepared by sol-gel and carbon adsorption. The main contents and conclusions were as follows:Spinel ZnFe₂O₄ nanoparticles were preared by a modified sol-gel route.In this route, the solution was better gelled by using acrylamide, simultaneously an appropriate amount of glucose was added to prevent the gel shrinkage during drying. The results showed that high-phase-purrity ZnFe₂O₄ nanoparticles can be prepared by using the chelating agent citric acid, ethylenediamine-tetraacetic acid （EDTA） and ethylenediamine-tetraacetic acid （EDTA） at a sintering temperature of 500℃. Using different chelating agent had influence on the grain size and morphology of ZnFe₂O₄ nanoparticles. By using citric acid as chelating agent the ZnFe₂O₄ nanoparticles have a good dispersion; the ZnFe₂O₄ nanoparticles by using ethylenediamine-tetraacetic acid （EDTA） as chelating agent has a certain effect on grain refinement, but with a certain degree of adhension phenomenon.Carbon adsorption is a new route to the preparation of nanoparticles, which is used the strong adsorption property of activated carbon. We analyzed the parameters, which included the amount of activated carbon, the pH value of solution, the sintering temperature to the influence of ZnFe₂O₄ nanoparticles.The results revealed that high-phase-purrity ZnFe₂O₄ nanoparticles can be prepared by carbon adsorption, the best parameters for carbon adsorption was: the molar ratio of activated carbon to metal atoms is 2:1, the solution pH value for 3, the sintering temperature for 500℃.Analysed and compared the morphology and magnetic of ZnFe₂O₄ nanoparticles prepared by sol-gel and carbon adsorption .The result revealed that high-phase-purrity ZnFe₂O₄ nanoparticles can be prepared by using two methods at the sintering temperature for 500℃.The ZnFe₂O₄ nanoparticles prepared by sol-gel and carbon adsorption have a smaller grain size and a good dispersion. The VSM showed the ZnFe₂O₄ nanoparticles displayed paramagnetic at room temperature.The hysteresis loop of ZnFe₂O₄ nanoparticles preparaed by carbon adsorption displayed an obvious "S" shape, explained that ZnFe₂O₄ nanoparticles prepared by carbon adsorptionwith a smaller size.更多还原