Research On Microstructure And Property Of Substituted M-type Barium Ferrite

The rapid development of modern communication and radar system requests ferrite circulators to be smaller, lighter and more ease of integration. Ferrite material is an important part of ferrite circulators and the optimization of its properties is very important to the improvement of ferrite circulators. Hexagonal ferrite is composed of strontium oxide, barium oxide and iron oxide, and it has a high anisotropy field. The high anisotropy field can produce an inside magnetic field in the ferrite material, so that, the ferrite circulators can work without an extra magnetic field or with a small extra magnetic field. So there is a great significance of producing M-type barium ferrite with large anisotropy field. In this thesis, we produced La-Co substituted, La-Mn substituted, La-Co-Mn substituted and La-Cu substituted M-type barium ferrite, and the relationship between densification, magnetic properties and substituted amount were studied. As the results showed:The activation energy and density of La-Co substituted M-type barium ferrite samples decreases with the increasing of the substituted amount, while the grain size and porosity increasing with the increasing of the substituted amount. The anisotropy field of the samples first increases then decreases with the increasing of the substituted amount, and it gets a maximum of 630 kA/m while the substituted amount x=0.3. The activation energy of La-Mn substituted M-type barium ferrite samples first increases slightly then decreases with the increasing of the substituted amount, while the grain size and porosity increasing with the increasing of the substituted amount. The density of La-Mn substituted M-type barium ferrite samples decreases with the increasing of the substituted amount. The anisotropy field of the samples first increases then decreases with the increasing of the substituted amount, and it gets a maximum of 636 kA/m while the substituted amount x=0.15. The activation energy of La-Co-Mn substituted Mtype barium ferrite samples first decreases then increases, while the grain size first increasing then decreasing with the increasing of the substituted amount. The density of La-Co-Mn substituted M-type barium ferrite samples decreases with the increasing of the substituted amount, while the porosity increasing with the increasing of the substituted amount. The anisotropy field of the samples first increases then decreases with the increasing of the substituted amount, and it gets a maximum of 815 kA/m while the substituted amount x=0.1. The grain size of La-Cu substituted M-type barium ferrite samples first increases then decreases with the increasing of the substituted amount, and the porosity first decreases then increases with the increasing of the substituted amount. The anisotropy field of the samples first increases then decreases with the increasing of the substituted amount, and it gets a maximum of 783 kA/m while the substituted amount x=0.1.