Synthesis Of W Type Ferrites And Their Magnetic Research

W-type ferrites have been used as permanent magnets for microwave devices, for high-density magnetic recording and for bubble domain memories in the form of thin monocrystalline layers due to their relatively strong anisotropy and moderated magnetization. Leccabue et al. have dicussed the magnetic properties of BaZn2Fe16O27 ferrites prepared by the coprecipitation method.Fine-particle ferrites show magnetic properties different from sintered materials. A wide range of chemical methods in the solution such as sol-gel, chemical coprecipitation, glass crystallization method have been used to obtain ultrafine mixed particles. In comparision with the classical ceramic methods, these methods have many advantages as follows: They reduce reaction temperatures; There is a finer and more homogenous granulometry in the obtained ferrites; Magnetic properties have greatly been improved under the same sintered temperatures.We have employed citric acid method to obtain W-type ferrite. Citric acid method as a solution-based method, which allows mixing of precursors at the molecular level, has an advantage in the preparation of ultrafine materials. In the citric acid method reagents are very simple, special equipment is not needed, dopants can be easily introduced into the final product, and agglomeration remains in a limited range. The attractive features of citric acid are its ability to synthesize materials with high purity, better homogeneity and high surface area in single steps.1. We have tried to synthesize W-type ferrite by citric acid method.The samples were characterized by X-ray diffraction(XRD) analysis and vibrating-sample magnetometer(VSM) in a field of 10.1KOe. Measuring results exhibit that crystal structures of final objects are the same as those of standard W-type sample and magnetic properties are different from those of counterparters gained by other methods.2. Effects of microstructures and magnetic properties in various conditions have been investigated. We have obtained the best synthesis conditions such as pH values, the amounts of citric acid and sintered temperatures. In this paper, we also discussed the mechanism of citric acid method. It's generally considered that nitrates and organic compounds behave to oxidants and fuels. The redox reaction takes place between them.3. Dopants can alter microstructures and magnetic properties of W-typeferrites to satisfy various requirements in different application realms. The high value of crystalline magnetic anisotropy is obtained by adding Co element to W-type ferrite. The amounts of Co element have great effects in coercivity. The rare earth ions affect magnetic properties and crystal microstructures. Those are attributed to changing crystal lattice constant and occupation of the Fe3+ cations in the different magnetic sublattices.