【作者】 张伟；

【导师】 马万勇；

【作者基本信息】 山东轻工业学院 ， 应用化学， 2009， 硕士

【摘要】 磁性Fe₃O₄纳/微米颗粒由于其特殊的磁学和电学性质,使得它在磁记录、磁流体、传感器、催化剂尤其是生物医药领域有着广泛的应用。本文采用水热合成法,低温下（90℃）制备了具有八面体形貌、高磁性的Fe₃O₄亚微米晶体。对典型八面体Fe₃O₄样品进行了XRD,SEM,TEM,XPS,FTIR和VSM表征。XRD和XPS分析表明,制备的Fe₃O₄亚微米晶物相纯净、结晶性良好。SEM和TEM分析表明,颗粒尺寸在200～300 nm,八面体晶粒形貌规整。XPS和FTIR分析表明,颗粒表面担载具有生物相容性的PEG-6000。VSM分析表明,样品饱和磁化强度为85.5 emu/g,矫顽力为118 Oe。对八面体Fe₃O₄颗粒的形成机理以及Fe₃O₄颗粒链状生长的机理进行了探讨。考察了体系的pH值、反应温度、反应时间、NaOH以及KNO₃滴加速率、初始NaOH溶液的浓度、阴阳离子对八面体Fe₃O₄的纯度、尺寸以及形貌的影响,通过XRD以及SEM对产物进行了分析。采用高温高压水热法制备了颗粒尺寸在的球形Fe₃O₄颗粒,对典型球形Fe₃O₄样品进行了XRD,TEM,VSM表征。结果表明:制备的球形Fe₃O₄颗粒物相纯净,颗粒尺寸为250～330 nm,相对于八面体Fe₃O₄晶体,晶体结晶性差。样品饱和磁化强度为90.3 emu/g,矫顽力为60 Oe,相对于八面体Fe₃O₄,球形Fe₃O₄颗粒有着较高的饱和磁化强度和较低的矫顽力。更多还原

【Abstract】 Magnetite Fe₃O₄ nano- and/or microparticles have been extensively applied in information storage, ferrofluids, sensors, catalysts, and especially biomedical fields due to their special magnetic and electrical properties.In this thesis, Octahedral Fe₃O₄ microcrystals with a relatively high magnetic saturation value have been prepared at a low temperature of 90°C via a hydrothermal approach. Typical octahedral Fe₃O₄ samples were characterized by means of XRD, SEM, TEM, XPS, FTIR, and VSM. The XRD and XPS analyses indicate a cubic phase of the as-prepared Fe₃O₄ submicrocrystals with high crystalline perfection. The SEM and TEM analyses show that the particle size distribution is in the range of 200～300 nm with regularly octahedral morphology. The XPS and FTIR analyses reveal that biocompatible PEG-6000 molecules cover the surface of Fe₃O₄ crystals. The VSM measurements show that the Fe₃O₄ octahedrons have a relatively high magnetic saturation value of 85.5 emu/g and a coercive field of 118 Oe. The formation mechanisms related to Fe₃O₄ octahedral crystals and their linear self-assembly structures are discussed.The effects of reaction parameters on the resulting product were investigated, including the starting materials, oxidizing agent, pH value, reaction temperature, reaction time, and dropping rate of NaOH and KNO₃ aqueous solution.Spherical Fe₃O₄ paticles with size range of 250～330nm were prepared by a solvothermal method in a Teflon-lined static autoclave. Typical spherical Fe₃O₄ samples were characterized with XRD, TEM and VSM. It is found that the crystallinity of spherical particles is lower in intensity than that of octahedrons. Although a higher magnetic saturation value of 90.3 emu/g possessed by the sphericals, a lower coercive field of 60 Oe occurs in comparison with those of octahedrons （85.5 emu/g and 118 Oe）.更多还原