The Study Of Preparation And Electromagnetic Properties Of Composite Substituted YIG Ferrites With Low Temperature Sintering

In this dissertation, Y2O3,Fe₂O₃,Bi₂O₃,V₂O₅,CaCO₃,In₂O₃ and SnO4 were used as the raw materials to prepare [Bi_0.75Y_1.05-xCa_1.2+x](Fe_4.4-xSn_xV_0.6)O₁₂ (Snx:Bi-CVG) and Y₂Bi₁Fe_5-xIn)_xO₁₂ ferrite materials by conventional ceramic technique. Based on this, the conventional oxide ceramics technique was improved. Y₂Bi₁Fe_5-xIn)_xO₁₂ ferrites were prepared by the method of Compound calcined process combining ion substitution. The bulk density, micro-structure, morphology and magnetic properties were investigated by XRD, SEM, MATS, Vector Network Analyzer and Microwave Ferrite Parameters Meter.⑴The moderate addition of Sn⁴⁺ in Bi-CVG could lower the sintering temperature and enhance the soft magnetic properties obviously. With the increase of Sn⁴⁺ content, the saturation magnetization first increased and then decreased, while the coercivity and the ferromagnetic resonance linewidth (ΔH) first sharply decreased and then slightly increased. Additionally, the specimen of [Bi_0.75Y_0.65Ca_1.6](Fe_4.0Sn_0.4V_0.6)O₁₂ sintered at 1075 ?C had the highest density and the optimum magnetic properties: RD (the relative density) = 98.49%, Hc = 152.3 A/m, 4πMs = 711.3×10-4 T,ΔH = 2.1 kA/m.⑵In-substitution may improve magnetic properties of Bi-YIG ferrite material. With proper In-substitution, a significant increase in saturation magnetization (4πMs), remanent magnetization (Br) and a considerable reduction in coercivity (Hc) will be achieved. Substitution of In3+ icon helps to reduce the sintering temperature to some degree. Also, there is no significant change with the addition of In₂O₃. When x = 0.4, the electromagnetic properties of the sample with sintering temperature of 1050℃are as follows:ρ=5.88g/cm³,4πMs=1029.0×10-4T,Hc=710.2 A/m,ε′is 10.0¹4.0, tgδe is 0.0015⁰.0085.⑶With the method of compound calcined process combining ion substitution, the sintering temperature of In doped Bi-YIG ferrites was decreased to 1000℃, and there was little change on the saturation magnetization(4πMs) and dielectric properties, also slight decrease of remannent magnetization (Br) and significant decrease of the coercivity (Hc) were achieved. Specific performance parameters are as follows: 4πMs = 998.8×10-4T, Hc = 0.646kA/m, Br=451.6×10-4T,ε' is 10.595 ¹3.257, tanδe is 0.0009⁰.0088,μ' is 1.045¹.298, tanδm is 0.0025⁰.0292.In summary, preparation and electromagnetic properties of composite substituted YIG ferrites with low-temperature sintered have been studied. Sn substituted Bi-CVG sintered materials, which have been successfully prepared, can not only be co-firing with the Ag-Pd (1145℃) electrode materials, but also significantly improve the magnetic properties of materials. The method of Compound calcined process combining ion replacement may significantly reduce sintering temperature; the material prepared can fully achieve co-fired purposes with the low-cost Cu electrode in the low temperature.