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Synthesis and Characterization of Ultrafine Well-dispersed Magnetite Nanoparticles

Author: WangHanBin
Tutor: LiuZuLi
School: Huazhong University of Science and Technology
Course: Condensed Matter Physics
Keywords: Nanoparticles Fe3O4 Control co-precipitation method Magnetic Dispersion
CLC: TB383
Type: Master's thesis
Year: 2004
Downloads: 661
Quote: 5
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Abstract


Due to the tiny size ( 1 - 100nm ) , the nanoparticles tend to be able to demonstrate the nature of many different macroscopic solid material . Especially in recent years , magnetic nanoparticles because of its significant value in the field of biology, medicine has been studied extensively . The direction of these applications include: fixed enzyme , protein , gene , radiopharmaceuticals , magnetic resonance contrast agent , immunoassay , RNA and DNA purification , targeted drugs and other biomedical fields . Preparation of magnetic nanomaterials becomes one of the important direction . In many method for preparing magnetic nanoparticles , the coprecipitation method has been widely used due to the operation of simple, low cost , high yield and other characteristics . But prepared by the particle diameter is typically greater than 8nm, and wide distribution , limiting its application value in many ways . The purpose of this study is the preparation of surplus small well-dispersed Fe3O4 nanoparticles . Citrate is introduced in the reaction to inhibit the growth of Fe3O4 particles , we prepared an average particle size of less than 5nm in the ultra- small particles , while a variety of preparation conditions to generate Fe3O4 particles size , crystallinity , surface adsorption , and magnetic properties of . The results show that : the size of the generated particles with the increase in the concentration of citrate in the reaction ; than the saturation magnetization of the Fe3O4 particles have significantly reduced due to the particle size decreases . In addition, the following conclusions were drawn in the preparation process : The reaction shall be carried out under anaerobic conditions ; final pH value of the reaction system had a significant effect on the the Fe3O4 particle diameter distribution and dispersion stability . The aqueous phase Fe3O4 particles dispersed . The results showed that the citrate in the the Fe3O4 particle surface chemical adsorption . Such adsorption leading to the surface of the particles with a negative charge to avoid mutual agglomeration , and the particles in 4 lt ; pH lt ; 12 wider range dispersed . In addition, the oxidation process of the ultra-small Fe3O4 particles are non- negligible factor of these particles can be oxidized in a few days at room temperature as gamma - Fe2O3 , although the latter magnetic decreased , it is not easily oxidized in air becomes high , the dispersion stability of the .

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