Properties Research And Expansion Of Ni-Zn Ferrite Prepared With Layered Precursor Method

Soft magnetic ferrite NiZnFe2O4 with low coercivity and high saturation magnetization has been the research target of people for quite a long time. With fine resistance, high Curie temperature, low temperature coefficient and well high-frequency performance, nickel-zinc ferrite materials have long been widely used in high-frequency magnetic recording fields such as VCRs (video cassette recorder), hard disk machines and floppy disc drives, where high-density magnetic recording is required. And recently, nickel-zinc ferrite materials start to be used as magnetic carrier for the immobilized enzyme as well, for they can control the movement of the magnetic immobilized enzyme through the external magnetic field and make immobilized enzyme separate and recovery from the reaction system easily.The performance of ferrite is closely related to its preparation methods. Nowadays, the ways to prepare the ferrites mainly include the traditional dry method, the wet chemical method and the layered precursor method. Both of them have the problems that the distribution of ions is uneven and the magnetic domain structure is quit complex and the ferrite materials prepared by them have the defect of small specific surface area and small pore volume. Compared with those traditional methods, NiZnFe2O4 prepared by layered precursor method possesses such properties as even ions distribution, fixed chemical composition, single magnetic domain structure and high saturation magnetization, exhibiting excellent magnetic properties. By introducing some ions into layered precursor, we can prepared porous NixZn1-xFe2O4 and NixMgyZn1-x-yFe2O4 ferrite and establishes the character of the ferrite.Chapter 1 is the introduction, which introduce researching background and the related theory review of the research. In chapter 2, we introduce the process of preparing NiZnFe2O4 ferrite with layered precursor method and the research of its property. In chapter 3, we introduce the preparing method and mainly property of the porous NixZn1-xFe2O4 ferrite magnetic materials. Comparing with NiZnFe2O4 ferrite, the porous NixZn1-xFe2O4 ferrite has larger pore volume and specific surface area. In chapter 4, we introduce the preparing method and mainly property of the porous NixMgyZn1-x-yFe2O4 ferrite magnetic materials.. Comparing with the porous NiZnFe2O4 ferrite, porous NixMgyZn1-x-yFe2O4ferrite has the alkali member of MgO which establishes the applied range of ferrite magnetic materials.Chapter 5 is the conclusion of the research. The conclusion includes: NiZnFe2O4 ferrite prepared with layered precursor method have high specific saturation magnetization (79.15emug-1), low coercivity (14 Oe). Comparing with NiZnFe2O4 ferrite, the porous NiZnFe2O4 ferrite has larger pore volume (0.027559 cm3/g to 0.161157 cm3/g) and specific surface area (from 3.8878m2/g to 16.3845m2/g). The pore distribution of the NixMgyZn1-x-yFe2O4 is even and the surface area of NixMgyZn1-x-yFe2O4 has been greatly improved after removing the ZnO. Comparing with the porous NiXZn1-XFe2O4 ferrite, porous NixMgyZn1-x-yFe2O4ferrite has the alkali member of MgO and can be used in drug slow release and immobilized enzyme.