Study On Preparation And Properties Of Ni-Zn Ferrites By Hydrothermal Method

The cubic spinel structured ferrites is an important kind of soft magnetic materials. Soft magnetic materials are used to make magnetic conductor, which coercive force is extraordinary small, typical valued about1A/m. Small coercive force means magnetic domain wall domains moves easily when the strength and direction of magnetic field is changed. Ni-Zn Ferrite is important cubic spinel structured ferrite. On purpose to prepare high quality Ni-Zn ferrite materials, traditional ceramic technology have fallen behind. In recent years the hydrothermal synthesis method is developed and used widely because of the advantages of low cost, simple technology, convenient operation, by which well-distributed particles and little agglomerated ultrafine powders are prepared. In this thesis using hydrothermal reactor and PEG (polyethylene glycol) as addition agent, Ni-Zn ferrite particles is synthesized by hydrothermal method, and properties are improved by doping. By changing four factors hydrothermal temperature, hydrothermal time, pH value and the contant of doped-Cu2+multiple experiments are made, and properties are compared among samples. Effect on structure and properties of Ni-Cu-Zn ferrite by doped-Co2+are investigated. Seek doping regulation to provide theoretical basis of preparing Ni-Cu-Zn ferrite with high quality and excellent properties.In this thesis Ni0.2ZnxCu0.8-xFe2O4(x=0.7,0.6,0.5,0.4) systems of ferrites and Co2+-doped Ni-Cu-Zn ferrite are introduced. In experiments CUSO4, ZnSO4, NiSO4, FeSO4, COSO4, NaOH is used as raw materials. Ni0.2ZnxCu0.8-xFe2O4(x=0.7,0.6,0.5,0.4) and Ni0.2Zn0.4Cu0.4-xCoxFe2O4(x=0.1,0.2,0.3,0.4) powders are synthesized by hydrothermal method under appropriate conditions. After sintering under different temperatures, the crystal structure, morphology, magnetic performance and dielectric and Permeability performance are characterized by XRD(X-ray Diffraction)、SEM(Scanning Electronic Microscopy)、 VSM(Vibrating Sample Magnetometer、Agilent and so on.Ni-Zn ferrite powders synthesized under180℃of hydrothermal temperature are studied in detail. The main impact factors are investigated, and powders structure and morphology as analysed by XRD and SEM. The results from different electrical property and magnetic property analysed by Agilent and VSM show that Ni-Zn ferrite which is synthesized by hydrothermal method have better electromagnetic performances than the same ferrite synthesized by solid state method.The structure and properties of doped-Co2+Ni-Cu-Zn ferrite synthesized by hydrothermal conditions are investigated. The result indicates that doped-Co2+Ni-Cu-Zn ferrite prepared via hydrothermal reaction have better permittivity, low dielectric constant and dielectric loss. Materials of low dielectric constant are suitable for application in high-frequency.