Fe₂O₃纳米粒子和纳米棒的制备研究

【作者】 姜国华；

【导师】 姜继森；

【作者基本信息】 华东师范大学 ， 物理化学， 2004， 硕士

【摘要】 γ-Fe₂O₃纳米粒子具有优良的磁性能，因此有关其制备和应用是纳米材料领域的一个研究热点，而粒子的颗粒形貌和尺寸是影响其使用性能的一个重要因素。因此，探索新的简单的制备γ-Fe₂O₃纳米粒子的方法仍具有重大的实际意义。一维纳米结构材料（纳米棒或纳米线）因其独有的小尺寸和维度而使其具有独特的电学，光学和动力学性质，这也使其在纳米器件与微型传感器方面具有潜在的应用前景。因而，有关一维纳米结构材料的制备和性能研究是近年来国内外研究的主要方向和前沿领域。氧化铁被广泛应用于半导体，磁记录材料，光催化剂等方面，有关其纳米薄膜和纳米粒子制备方面已有许多相关研究，但有关其纳米棒或纳米线制备方面的报道不多。 本论文中，用简单的（湿）固相研磨法制备得到γ-Fe₂O₃纳米粒子。通过液相反应-焙烧法制备得不同形貌的γ-Fe₂O₃纳米粒子。通过在溶液中加入适当的表面活性剂制得前驱物再将前驱物热处理得到α-Fe₂O₃纳米棒。运用XRD、M（?）ssbauer谱、TEM、TG-DTA、FTIR等手段对所得的纳米粒子和纳米棒样品进行了表征，并对制备过程进行讨论和研究。 主要结果如下： 在聚乙二醇（PEG-400）存在的条件下，室温研磨适量FeCl₃与NaOH的混合物制备了γ-Fe₂O₃纳米粒子。实验结果证明：所得产品经洗涤、在空气中于60℃下干燥后即可得结晶较差的γ-Fe₂O₃纳米粉体，经450℃热处理1h后得粒径约为30nm结晶较好的γ-Fe₂O₃纳米粒子，500℃热处理1h后得到粒径约为40nm左右、结晶完好的γ-Fe₂O₃纳米粒子。 发现三氯化铁与氢氧化钠反应时加入有机物聚乙二醇，所得沉淀不洗涤除去NaCl直接干燥并在300℃热处理得到长径比约为6的棒状γ-Fe₂O₃纳米粒子，其中长约为200nm，直径在30nm左右，否则将得到立方体形γ-Fe₂O₃粒子，粒子尺寸在20 nm左右。同时讨论了聚乙二醇的加载量对粒子晶相和形貌的影响。当聚乙二醇的加载量为2ml／60mlH₂O时，样品300℃热处理后得到的γ-Fe₂O₃纳米粒子的粒径为最小，此加载量为聚乙二醇的最佳加载量。 通过在FeSO₄-NH₄Ac溶液中加入表面活形剂十二烷基硫酸钠（SDS），华东师范硕!:学位论文辛基酚聚氧乙烯（9）醚（TritonX一1 00）和十六烷基三甲基嗅化钱（CTAB）发生陈化反应，研究不同浓度的SDS，TritonX一100和十六烷基三甲基澳化钱（CTAB）对前驱物粒子形貌的影响，发现SDS的加入使粒子的长径比大大增加，并且【SDS压e1值为0.15时前驱物粒子的平均长径比最大，为25（样品记为NR4），而Tritonx一1 00与CTAB则对粒子形貌没有影响。并且通过在500℃热处理NR4获得了长径比约在15一20之间的a一FeZO3纳米棒，其中长约为500·600刊m，直径约为30nm左右。此方法相对现有的金属氧化物纳米棒制备方法来说比较简单，易于操作，原料廉价易得，反应条件易于控制。更多还原

【Abstract】 The preparation and application of γ-Fe2O3 nano-particles are currently attracting considerable attention because of their excellent ferromagnetic properties. And the morphology and size of particles are important factors to influence their performance. Thereby it is still significant to find new preparation methods of γ-Fe2O3 nano-particles.Nanoscale one-dimensional structures have attracted many people to research because of their unique electric, optical, and mechanical properties as a result of their low dimensionality, which also results in their potential applications in nanodevices and microsensors. Thereby a number of recent studies have been focused on the preparation and research of properties of nanoscale one-dimensional structures. Iron oxides are widely used as semiconductor , recording materials and photocatalyst. Nanostructured Fe2O3 thin films and particles have been prepared, and little work exists for Fe2O3 nanorods or nanowires.In this thesis, γ-Fe2O3 nano-particles were prepared by using simple (wet)solid -phase grinding method. And different morphological γ-Fe2O3 nano-particles were prepared by using solution reaction-calcining method. By adding one kind of surfactant and resultant calcining of precursors, α-Fe2O3 nanorods were synthesized. The resultant samples were characterized by XRD,Mossbauer Spectroscopy, TEM, TG-DTA, FTIR and the preparation process was also studied.The main results are as follow:In the presence of polyethylene glycol(PEG-400), the mixture of FeCl3·6H2O and NaOH was grounded and the γ-Fc2O3 nanoparticles were prepared. The product obtained was washed and dried at 60℃ and calcined at different temperatures for Ih. XRD. Mossbauer Spectroscopy, TEM, TG-DTA and FTIR were used to characterize the samples. The results show that after dried at 60℃ for 2h, the as-grounded sample was transformed into poor-crystalline γ-Fe2O3 ultrafine powder. After being calcined at450℃ for 1h,the ultrafine powder became good crystalline γ-Fe2O3 nanoparticles with particle size of 30nm. After being calcined at 500℃ for 1h, perfect-crystalline γ-Fe2O3 nanoparticles were gotten with particle size of 40nm.When FeCl3 and NaOH react, if PEG added and the resultant deposit not being washed, the rod-like γ-Fe2O3 nanoparticles were gotten with aspet ratio at ca.6, length ca.200nm, width ca.30nm,otherwise the cubic-like γ-Fe2O3 nanoparticles were gotten with particle diameter at about 20nm. We found the loading amount of PEG affects the composition and morphology of particles. When the loading amount of PEG is 2ml/60mIH20, the particle size of γ-Fe2O3 by calcining of sample at 300℃ is minimum, thereby the loading amount of PEG 2ml/60mlH2O is optimal.By adding surfactants-sodium dodecyl sulphate(SDS) , TritonX-100 and CTAB into the solution of FeSO4- NH4Ac, we studied their effect on the morphology of precursor. No effect on the morphology of precursor was observed for TritonX-100 and CTAB, but the addition of SDS progressed the particle growth and the aspect ratio(25) of particles is maximum when [SDS/Fe] is 0.15(the sample marked as NR4). After NR4 was calcined at 500℃ α-Fe2O3 nanorods were gotten with aspect ratio at about 15-20 (length 500-600nm,width 30nm)更多还原