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Study on Preparation and Properties of CoFe2O4 Ferrite and Its Composites

Author: LiuHongYan
Tutor: DaiJianMing
School: Huaibei Normal
Course: Materials Physics and Chemistry
Keywords: CoFe2O4 Composites Magnetic annealing Magnetic properties Microwave absorption
CLC: TB383.1
Type: Master's thesis
Year: 2011
Downloads: 63
Quote: 0
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Abstract


With the rapid development of microwave communication technology, more and more serious electromagnetic pollution, electromagnetic immunity and microwave absorbing material received extensive attention. Magnetic micro-nano structural material due to its unique micro-structure and magnetic and electric properties, is expected to become a new high-performance microwave absorbing material and become a hot topic. Of CoFe 2 O 4 high saturation magnetization and high Snoek limit, and high permeability in a wide frequency range, making this type of material in a wide frequency range as thin The absorber has an important value. , Despite the variety of preparation techniques have been reported and the use of method induced by the magnetic field changes, however, the morphology, structure and microwave absorption properties reported rare, there are to be further studied. The papers using chemical co-precipitation method Preparation of CoFe 2 O 4 particles and their composite materials, preparation of samples by annealing in a magnetic field a more systematic study of the magnetic field morphology structure as well as magnetic and microwave absorption properties. The main work includes the following sections: (1) chemical coprecipitation, respectively, in zero magnetic field and the magnetic field strength of 0.5T, 800 ℃ temperature annealing the the synthetic of CoFe 2 O 4 particles. By XRD, SEM, magnetic and microwave absorption performance test analysis showed that the magnetic field annealed sample crystallinity changed for the better, to become more rounded cylindrical particles of CoFe2O4 particles due to the magnetic field induced. Meanwhile, the increase in the saturation magnetization of the sample and the magnetic permeability, is more conducive to achieve impedance matching and improve microwave absorbing properties. (2) the use of chemical co-precipitation method in the hollow microspheres coated with a layer of CoFe 2 O 4 , a low-density hollow magnetic microspheres. Structure morphology and magnetic properties were characterized by XRD, SEM, SQUID technology. Vector network analyzer measurement samples and paraffin mixture in the broadband segment (2-18GHz) complex permittivity and magnetic permeability, reflection loss curve of the sample through computer simulation. The results showed that the samples of the coated structure of CoFe 2 O 4 / hollow ball is a lightweight microwave absorbent material. (3) using the hydrothermal method and chemical co-precipitation method and two-step synthesis of ZnO / CoFe 2 O 4 composite sample. The micro-structure and performance test results show that the the ZnO/CoFe2O4 complex relative to the pure of CoFe 2 O 4 better microwave absorbing properties. The CoFe 2 O 4 and ZnO magnetic loss and dielectric loss combination, it is possible to obtain a lightweight, strong absorption of the microwave absorbent material.

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