Study On Barium Ferrite Lattice Doping And Microwave Sintering

Barium ferrite is widely used as permanent magnetic materials and microwave absorbing materials due to its cheap and good chemical stability. The Curie temperature, coercivity and permeability can be controlled by doping barium ferrite with other elements. That enhanced the performance of barium ferrite. However, the high sintering temperature, long sintering time, and complex doping process are still the shortcomings of the conventional sintering process, which constrained the research and application of barium ferrite. In this paper, conventional sintering technology and microwave sintering were compared, the process of sinter barium ferrite, manganese doping barium ferrite, lattice doping and surface defects were also discussed in this article.Barium ferrite was obtained by sinter coprecipited barium ferrite precursor in different temperature. The effects of sinter time, sinter temperature and microwave absorbing material were studied in this article by comparing the conventional sintering and microwave sintering. The conclusions are:①The temperature of barium ferrite conventional sintering is high, usually about 1300℃, the temperature of barium ferrite microwave sintering with SiC is lower than the temperature of barium ferrite conventional sintering, usually about 1000℃, the temperature of barium ferrite microwave sintering without SiC is lowest, usually around 700℃, the mass susceptibility of microwave sintered barium ferrite without microwave absorbing materials is much higher than the one sintered by conventional device and the one sintered with microwave absorbing materials.②With the Fe/Ba ratio increased, the sintering temperature of barium ferrite reduced, The Fe/Ba ratio should not large than 12 or small than 10, Fe/Ba ratio of 11 is the optimal ratio in barium ferrite, otherwise, it will form unexpected products.③The differential thermal analysis shows with the increase of manganese content in barium ferrite, the absorption peaks of barium ferrite temperature decrease from 1191℃to 1078℃.④XRD patterns show that the crystal structure and spectra of different Fe/Ba ratio barium ferrite and manganese doped barium ferrite were crystal and as same as crystal BaFe12O19, the manganese was doped in the form of a lattice structure in the crystal.The comparison of conventional sintering, microwave sintering with microwave absorbs materials, and microwave sintering without microwave absorbing materials were based on the experimental data and theoretical analysis. The study shows the dielectric loss of barium ferrite in electromagnetic fields caused by microwave is the key to heating itself to the sinter temperature, which rapid sintering densification. Barium ferrite was self heating by dipole rotation and conductivity loss. An induction period existed in the heating process. The mass susceptibility of microwave sintered barium ferrite without microwave absorbing materials is much higher than the one sintered by conventional device and the one sintered with microwave absorbing materials. The manganese was not only contribution in replacing the iron element to form lattice replacement, but also contribution in microwave absorption.