Low Temperature Sintering YIG Ferrite And Its Application

With the development of 5G wireless communication technology,low loss low temperature co-fired ceramics（LTCC）materials have attracted more and more attention.For many years,LTCC technology has been a good process technology in the field of passive devices and integrated circuit packaging,because it can integrate low-loss dielectric materials,multilayer films and passive devices.Yttrium iron garnet(Y₃Fe₅O₁₂,YIG)is used to fabricate passive microwave components,such as isolators,circulators,phase shifters and micro antennas,due to its excellent properties.Its operating frequency range is 1-100GHz.The sintering temperature of YIG material is generally above 1400°C,but to apply it to the LTCC process,the sintering temperature needs to be lowered to below 960°C to achieve low temperature co-firing with silver（Ag）electrodes.This paper focuses on the research of YIG gyromagnetic ferrite substituted by different ions under low temperature sintering,hoping to use different doping substitution to realize its low temperature sintering characteristics and improve the performance of low temperature sintered YIG gyromagnetic ferrite,and finally through the simulation of microstrip circulator optimize the application value of verification materials.Firstly,use low melting point oxide Bi₂O₃ as the raw material,and replace part of the Y³⁺ions with Bi³⁺ions,which can reduce the activation energy of the reaction process during the sintering process,and significantly reduce the sintering temperature of the YIG gyromagnetic ferrite.Bi:YIG ferrite was prepared,and the effect of the amount of Bi³⁺substitution on the properties of YIG gyromagnetic ferrite was studied.Bi:YIG can successfully form a garnet phase when sintered at a low temperature of 900-960℃,but the ferromagnetic resonance linewidth is too high（>400Oe）.Through analysis,it is found that the amount of iron in Bi:YIG may be too high.Therefore,an experiment to reduce Fe content was carried out on the basis of Bi:YIG,and it was found that compared with the experiment without iron deficiency,the performance parameters of the material have been improved,especially when the iron deficiency x=0.3,the ferromagnetic resonance line width reaches the minimum value is 203Oe.Then,V₂O₅,Zn O and Ni O were added as raw materials on the basis of Bi³⁺ion substitution.The effect of multi-element replacement on the structure and electromagnetic properties of low-temperature sintered YIG gyromagnetic ferrite was studied.It is found that at a sintering temperature of 960℃,when the substitution amount x=0.04,the coercivity of the Bi³⁺-Zn²⁺-V⁵⁺ternary ion substituted ferrite reaches the minimum value of 13.5Oe.The Bi³⁺-Ni²⁺binary ion-substituted ferrite sample has a single phase corresponding to the garnet structure when sintered at 900～960℃,which belongs to the Ia3d space group.As the amount of Ni²⁺substitution increases,the crystallinity first increases and then decreases.When the substitution amount is 0.1,the coercivity reaches the minimum value of 14.2Oe.Finally,using the material parameters obtained in the previous experiment,saturation magnetization 1604Gs,ferromagnetic resonance line width 418Oe,design the device model structure and size,establish a simulation model of the microstrip circulator,simulate analysis and optimize.Finally,a circulator structure with a relative bandwidth greater than 20%,return loss and isolation greater than 15d B,transmission loss less than1d B,and VSWR less than 1.3 is obtained.