【作者】 侯生益；

【导师】 吴文伟；

【作者基本信息】 广西大学 ， 应用化学， 2008， 硕士

【摘要】 铁酸盐是一类重要的合成磁性氧化物,它有几种不同的晶体结构。其中,尖晶石型是一种最重要的结构,它又分尖晶石和反尖晶石结构两种。铁酸盐被广泛用于许多领域,如铁磁流体,磁药物传输,磁高密度信息存储。铁酸镍和铁酸镍锌是两种重要的铁酸盐,它的性质与合成方法有关,长期以来一直是人们关注的焦点。为此,本研究采用低热固相反应法合成了NiFe₂O₄和Zn_0.5Ni_0.5Fe₂O₄纳米晶。同时,对Zn_0.5Ni_0.5Fe₂O₄结晶动力学进行了研究。本研究论文共分为四章:第一章绪论综述了固相反应法制备无机材料的原理、研究进展及其在合成无机材料中的优点。介绍了铁酸盐的性质、用途及其合成研究进展。并对结晶动力学进行了概述。第二章铁酸镍的低热固相合成与表征在表面活性剂聚乙二醇-400存在下,以NH₄HCO₃、NiSO₄·7H₂O、Fe₂（SO₄）₃为原料,采用低热固相法合成了反尖晶石型NiFe₂O₄纳米晶,用TG/DTA、IR、XRD、TEM和VSM对前驱体及其煅烧产物进行表征。用均匀设计法确定最优实验条件。获得的最佳条件为:NH₄HCO₃与NiSO₄·7H₂O的物质量比为10,表面活性剂（聚乙二醇-400）的用量为499.8μL,研磨时间为38min,前驱体的灼烧温度为550℃,前驱体的灼烧时间为170min。在最佳条件下,得到了近似球形、平均颗粒粒度约为55nm的立方晶反尖晶石结构的铁酸镍纳米晶。NiFe₂O₄的比饱和磁化强度为50.7emu·g-1,矫顽力Hc为40Oe,剩磁Mr为1.5emu·g-1,结晶度为88.5%。第三章铁酸镍锌的低热固相合成与表征以ZnSO₄·7H₂O、NiSO₄·7H₂O和NH₄HCO₃为原料,采用低热固相法合成Zn_xNi_1-xFe₂O₄。用TG/DTA、IR、XRD、SEM和VSM对前驱体及其煅烧产物进行表征,用均匀设计法确定最优条件。获得的最佳条件为:x=0.5,NH₄HCO₃用量为理论量的1.2倍,煅烧温度为800℃。在此条件下,得到了组成为Zn_0.5Ni_0.5Fe₂O₄、形貌近似球形、平均颗粒粒度约为59.1nm的立方Zn_0.5Ni_0.5Fe₂O₄纳米晶。该产物的比饱和磁化强度为75.4emu·g-1,矫顽力Hc为40Oe,剩磁Mr为3emu·g-1,结晶度为91.5%。第四章铁酸镍锌的结晶动力学研究分别以等温结晶动力学分析理论和非等温结晶动力学分析理论为基础,研究了Zn_0.5Ni_0.5Fe₂O₄的晶化过程。等温结晶动力学分析理论研究结果表明:结晶活化能为110.6～113.3kJ/mol,结晶指数Avrami参数（n）为0.2～0.6之间,结晶过程以三维（3D）生长机理的Jander模型处理。非等温结晶动力学分析理论结果表明,Zn_0.5Ni_0.5Fe₂O₄的结晶过程的结晶活化能为155.6～242.4KJ·mol^-1,结晶指数Avrami参数（n）为0.4579,频率因子1nv为17.81～36.16。动力学机理函数为Jander模型中的三维扩散机理函数g（x）为[1-（1-x）^1/3]^1/2。更多还原

【Abstract】 Ferrites are a broad class of complex magnetic oxides of considerable technological importance,which occur in several different crystal structure forms.Within this group,spinel is a kind of the most important structure that occurs in two forms:spinel and inverse spinel structure.Ferrites are widely applied in many fields such as ferrofluids,magnetic drug delivery,magnetic high-density information storage.Nickel ferrite and zinc nickel ferrite are two kinds of ferrites which properties depend on their preparation methods.Therefor,they have been received considerable amount of attention.In this paper,pure phase nanocrystalline NiFe₂O₄ and Zn_0.5Ni_0.5Fe₂O₄ were synthesized via solid-state reaction at low heat.Besides, thermal decomposition kinetics of Zn_0.5Ni_0.5Fe₂O₄ precursor and crystallization kinetics of Zn_0.5Ni_0.5Fe₂O₄ were also investigated.The paper consists of four chapters:Chapter one:IntroductionPrinciple,preparation progress,and its advantage of preparing inorganic material via solid-state reaction were summarized.Characteristic,purpose,and preparation progress of ferrite were also introduced.Crystallization kinetics of was summarized.Chapter two:Preparation of NiFe₂O₄ via solid-state reaction at low heat and CharacterizationThe nanocrystalline NiFe₂O₄,with inverse spinel structure,was obtained via solid-state reaction at low heat in the presence of surfactant PEG-400 when NiSO₄·7H₂O,Fe₂（SO₄）₃ and NH₄HCO₃ were used as raw materials.The precursor and its calcined products were characterized by TG/DTA,IR,XRD,TEM,and VSM.The uniform design method was used for obtaining the optimal experimental conditions.The optimal experimental conditions as follow:molar ratio of NH₄HCO₃ to NiSO₄·7H₂O was 10:1,PEG-400 dosage was 499.8μL, grinding time was 38 min,calcining temperature and time were 550℃and 170 min respectively.The cubic NiFe₂O₄ crystalline with inverse spinel structure was obtained under the optimum conditions.Its appearance close to roundness,and average diameter about 55 nm. The saturation magnetization of NiFe₂O₄ was 50.7 emu·g-1,coercive force Hc was 40 Oe, remanence Mr was 1.5 emu·g-1,and crystallinity was 88.5%.Chapter three:Preparation of zinc nickel ferrite via solid-state reaction at low heat and CharacterizationThe Zn_xNi_1-xFe₂O₄ was prepared via solid-state reaction at low heat when ZnSO₄·7H₂O, NiSO₄·7H₂O,Fe₂（SO₄）₃,and NH₄HCO₃ were used as raw materials.The precursor and its calcined products were characterized by TG/DTA,IR,XRD,SEM,and VSM.The uniform design method was used for obtaining the optimal experimental conditions.The optimal experimental conditions as follow:x=0.5,NH₄HCO₃ dosage is as 1.2 times as theoretic value, grinding time was 38 min,calcining temperature was 800℃.The cubic Zn_0.5Ni_0.5Fe₂O₄ crystalline was obtained under the optimum conditions.Its appearance closes to roundness, and average diameter was about 59.1 nm.The saturation magnetization of Zn_0.5Ni_0.5Fe₂O₄ was 75.4 emu·g-1,coercive force Hc was 40 Oe,remanence Mr was 3 emu·g-1,and crystallinity was 91.5%.Chapter four:Study on crystallization kinetics of Zn_0.5Ni_0.5Fe₂O₄A study on crystallization process of Zn_0.5Ni_0.5Fe₂O₄ was carried out on the basis of theory of isothermal and non-isothermal crystallization kinetics.The kinetics parameters and mechanism functions of Zn_0.5Ni_0.5Fe₂O₄ crystallization process were obtained from different analysis theories respectively,that is:E = 110.6～113.3 kJ/mol,crystallization exponent Avrami constant（n）= 0.2～0.6,3D for growth mechanism for isothermal crystallization kinetics theory based on Jander model,and E = 155.6～242.4 kJ/mol,crystallization exponent Avrami constant（n）= 0.4579,lnv= 17.81～36.16 for non-isothermal crystallization kinetics theory,and crystallization kinetics mechanism function g（x）was[1-（1-x）^1/3]^1/2,which is one of the Jandle model.更多还原