【作者】 李享；

【导师】 杨海滨；

【作者基本信息】 河南理工大学 ， 矿物加工工程， 2007， 硕士

【摘要】 本文主要对Fe₃O₄纳米颗粒的制备,及其在空气中通过热处理向γ-Fe₂O₃和α-Fe₂O₃的转变,纳米Fe₃O₄与β-环糊精、空心玻璃微珠核壳结构复合材料的制备和性能表征进行了较为系统的研究。用还原沉淀法合成纳米Fe₃O₄颗粒,通过微波吸收材料（RAM）反射远场雷达截面（RCS）测量法对产物的微波吸收性能进行测量,证实其为优良的高频段微波吸收材料。在空气中分别对纳米Fe₃O₄颗粒进行150℃、200℃、300℃和400℃下30min的热处理,通过X射线衍射仪（XRD）和振动样品磁强计（VSM）测试得出300℃以下时产物为具有超顺磁性的γ-Fe₂O₃纳米颗粒,400℃时样品全部转化为α-Fe₂O₃纳米颗粒并由于产物粒径的增大而产生800Oe矫顽力,随着热处理温度的升高,产物出现烧结现象。分别在不同反应温度、不同反应时间及不同摩尔比例的条件下将β-环糊精包覆于Fe₃O₄纳米颗粒表面,形成具有较好单分散性及较小粒径的Fe₃O₄/β-环糊精纳米复合颗粒。探讨了包覆机理,发现β-环糊精对Fe₃O₄颗粒的包覆能够有效的抑制Fe₃O₄颗粒的长大并可以提高其在空气中的稳定性,并观察到该复合颗粒分散于水中在磁场的作用下具有磁光现象。在较低合成温度下β-CD能大大降低颗粒尺寸对合成时间的敏感性,这为稳定获得小尺寸Fe₃O₄颗粒提供了一条新途径。将Fe₃O₄纳米颗粒均匀地沉积到经预处理的空心微珠表面,得到密度仅为0.4-0.5g/cm3并具有超顺磁性的复合颗粒;通过改变空心微珠的装载量能控制包覆层厚度。该复合颗粒的饱和磁化强度可以通过改变玻璃微珠装载量及反应温度加以控制。提出Fe₃O₄对空心玻璃微珠的包覆机理。更多还原

【Abstract】 In this paper, the preparation of Fe₃O₄ nanoparticles; the conversion of Fe₃O₄ toγ-Fe₂O₃ andα-Fe₂O₃; the preparation and properties of Fe₃O₄/β-CD and GMB/Fe₃O₄ core-shell composite materials were systemically studied, respectively.Fe₃O₄ nanoparticles were synthesized by reduction-precipitation method in water solution. The microwave absorbing property of the sample was measured by RAM reflectivity far-field RCS which showed that Fe₃O₄ nanoparticle was a kind of good microwave absorbing material at high-frequency. The products of Fe₃O₄ heated at 150℃, 200℃, 300℃and 400℃were characterized by XRD and VSM. It was observed that Fe₃O₄ transformed forγ-Fe₂O₃ with superparamagnetic character at 300℃, then transformed forα-Fe₂O₃ when the temperature reached 400℃. The coercive force （800Oe） ofα-Fe₂O₃ appeared along with the particle size grew. The products agglutinated along with the temperature elevated.β-CD was placed into the preparation solution of Fe₃O₄ at different reaction temperature, different reaction time and different mole of proportion to prepare good dispersivity Fe₃O₄/β-CD composite material. The preparation mechanism of Fe₃O₄/β-CD was discussed. The magneto-optical phenomenon was observed. It also found that theβ-CD coating could restrain the growth of Fe₃O₄ nanoparticles and enhance their stability in air. The sensitivity of particle size to reaction time was greatly reduced at low temperature which provided a new method to obtain Fe₃O₄ particles with small size.We coated Fe₃O₄ nanoparticles on the surfaces of the pretreated GMBs to provide superparamagnetic hollow microspheres with low density （0.4-0.5g/cm3）. The magnetization of GMB/Fe₃O₄ could be controlled by changing the GMB content and the reaction temperature. The mechanism of how Fe₃O₄ nanoparticles coated on the surfaces of GMBs were proposed.更多还原