The Research Of High Performance Gyromagnetic Ferrite Materials And Their Applications

The development of the modern electronic and information technology has made the gyromagnetic ferrite devices essential for applications in a wide range of industry fields. Yttrium iron garnet, usually YIG, is a very promising material in gyromagnetic ferrite devices which are becoming smaller in size, lighter in weight, and more highly integrated, due to its narrow ferromagnetic resonance linewidth, good temperature stability and low dielectric loss.In the respect of material studies, this paper mainly focused on YIG. Firstly, the preparation process of YIG samples was studied. Traditional oxide method was applied to prepare YIG sample. Sintering temperature was used as the main variable of the preparation process. YIG samples were tested via XRD(X-Ray Diffration), SEM(Scanning Electron Microscope) and VSM(Vibrating Sample Magnetometer). The results showed that 1450℃ was the best sintering temperature for YIG. Then, the effect on the properties of YIG substituted by different ions Al3+, Gd3+ and In3+ was studied. The analysis of phase structure and microscopic morphology on Al3+, Gd3+ and In3+ substituted YIG samples indicated that the best compositions of Al3+, Gd3+ and In3+ were x=1.2 for Y3Fe5-xAlxO12, x=1.8 for Y3-xGdxFe5O12, and x=0.45 for Y3Fe5-xInxO12, respectively. Magnetic properties of those samples were tested. Al3+ Substitution could reduce the saturation magnetization 4?Ms and in the meantime keep a relatively narrow ferromagnetic resonance linewidth ?H of YIG. Gd3+ Substitution also had a reduction on 4?Ms, not so steep as it was for Al3+ Substitution. Besides, the introduction of Gd3+ could make a better temperature stability for YIG. Gd3+ Substitution, on the other hand, In3+ could mildly narrow the ?H of YIG and lower its dielectric loss, which was good for low loss devices.In terms of the study on the application of YIG materials, a circulator was designed and fabricated. After a brief introduction of the operating theories for ferrite junction circulators, a model of a YIG based circulator was created and simulated on the ANSYS HFSS platform. The results of the simulation showed that the transmission loss of the circulator was about-0.15 dB at X-band, and the return loss and isolation were both below-20 dB. A real circulator based on the simulated model was fabricated eventually. Relative tests suggested it a working circulator with a good performance corresponding to the simulated one, which proved that the gyromagnetic ferrite YIG had a promissing application in ferrite devices.