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This paper selects the biocompatibility Fe 3 O 4 and chitosan as an object of study in order to study the impact of the external magnetic field of magnetic nanomaterials prepared, in different magnetic field conditions The preparation of magnetic nanoparticles and magnetic nanocomposites, and the structure and nature of the products were characterized and analyzed the study: 1) 0 T, 0.25 T, 0.45 T in different magnetic fields using the Massart hydrolysis Preparation Fe 3 O 4 nanoparticles. The results show that: 0 T, the particles were spherical; the strength of the magnetic induction of 0.25 T and 0.45 T, the particles along a crystal plane orientation growth is one-dimensional rod-like structure, and the degree of crystallinity increased, the specific surface area decreases. All Products show superparamagnetic and obtained under Fe ; over 0 T 3 O 4 nanoparticles, 0.25 T and 0.45 T obtained under saturated particle magnetization 0.28 times and 1.14 times, and the residual magnetization were increased to 13.48 and 14.10 times the coercive force are increased by 1.45 times. 2) Fe3 and Fe2 pre uniformly dispersed in the chitosan acetic acid solution, 0 T, 0.25 T, 0.45 T in different magnetic fields using a one-step preparation Fe of 3 O 4 / chitosan composite. The results show that the: Fe 3 O 4 with chitosan presence of a bond and the formation of a stable core / shell structure. Chitosan environment, the external magnetic field induced by Fe 3 O 4 nanoparticles along certain crystal plane orientation growth, to generate chain or rod-like particles, the specific surface area decreases. 0 T, 0.25 T, 0.45 T in different magnetic field under the conditions obtained Fe 3 O 4 / chitosan composite performance superparamagnetic, but its associated magnetic parameter is not much difference. 3) The the preliminarily prepared Fe 3 O 4 nano-particles, and then embedded in the chitosan, at 0 T, 0.25 T, 0.45 T different magnetic field using a two-step the prepared Fe 3 O 4 / chitosan composites. Glutaraldehyde cross-linking process, the introduction of an external magnetic field, Fe 3 O 4 the particle itself morphology did not change significantly, does not appear one-step chain or rod-like particles , but a large number of the Fe 3 O 4 / chitosan particle orientation gathering arranged like structure showing the fiber bundles. According to the theory of crystal growth, a more systematic analysis of the growth mechanism of the magnetic field Fe 3 O 4 nanocrystals, as well as one-dimensional structure forming mechanism, and experimental phenomena and experimental results as the basis for a reasonable explanation.
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