| As functional ceramics, microwave ceramics have excellent dielectric properties and have already widely used on mobile communication, satellite communication,microwave communication,electronic countermeasure,aircraft-borne and ECM equipment, they have also greatly promoted the development of related domain.With the rapid development of mobile communications and information technology, higher requirements have been put forward to microwave circuit components on the basis of microwave ceramic, which is make microwave circuit components further miniaturization. Low temperature co-fired ceramics(LTCC)technology which applied in communication system has been an important approach to actualize miniaturization, low-cost and modulization of various components,Co-firing which achieved microwave dielectric ceramics with high conductivity of silver or copper electrode is a key. Therefore,in ensuring good dielectric properties of the material premise,reducing the sintering temperature of the material, so that it can co-fired with Cu or Ag electrode in low sintering temperature ceramic,which has become an inevitable trend for future development.Using low-melting point glass or oxides additives is the common method, which was found to effectively lower the sintering temperature. However, the microwave dielectric properties of the ceramic materials will be degraded seriously due to the formation of amorphous phase resulting from the addition of glass of oxides materials.Therefore, many researchers are currently turning to those inherent low sintering temperature of the microwave dielectric ceramics system.This paper studies the Ca3LiCoV3O12, Ca3LiNiV3O12, Ca3LiZnV3O12 three microwave dielectric ceramic materials,the original powder of three materials were mixed and milling according to the stoichiometry,using conventional solid-phase method to prepare a ceramic sample.Specific contents and results are as follows:(1)For Ca3LiCoV3O12 ceramics were prepared some samples under different sintering temperature,we studied their microstructure, sintering characteristics and microwave dielectric properties.Studies have shown that:Ca3LiCoV3O12 ceramics sintered dense at 900℃,and this time have good dielectric properties:εr=15.32,τf=-57.31ppm/℃,Q×f=22957GHz;bulk density ρ=3.41g/cm3,which has reached 93.8% of theoreticaldensity.Combined XRD patterns of samples prepared under different sintering temperatures and their corresponding bulk density map,Show that it have been able to crystallize well at 800 ℃,With increasing temperature does not generate a second phase,sintered samples at different temperatures showed the same crystal structure,grains exhibit hexagonal columnar and closely packed.The ceramic can be co-fired with silver electrodes at 900 ℃,and closely、no interfacial reaction 、no diffusion phenomenon.it has good low-temperature sintering matching and co-fired properties,the LTCC microwave dielectric ceramic materials have application values.(2)Ca3Li NiV3O12 ceramics sintered dense at 900 ℃, and this time have good dielectric properties:εr=11.84;bulk density ρ=3.48g/cm3,which has reached 95.8% of theoretical density.It’s crystallization conditions similar trend with CLCV, grains show ellipsoidal and closely.The materials have application values.(3)Ca3Li ZnV3O12 ceramics sintered dense at 875 ℃, and this sample have good dielectric properties::εr=15.32; τf=-63.57ppm/℃; Q×f=45143GHz; bulk densityρ=3.41g/cm3, which has reached 90.1% of theoretical density.It’s crystallization conditions similar trend with CLCV, grains show ellipsoidal and closely.The materials have application values.(4)These three ceramic materials have the following in common:bulk density along with increasing the sintering temperature show a decrease after the first increase.Relative dielectric constant along with increasing the sintering temperature show a same trend with bulk density.The relative dielectric constant varies depending on the change in density.All of this exhibit the same crystal structure-the body centered cubic ia3 d space group and they belong to the same system, similar in nature;The reason why the Q value of CLZV better than the other two is that it’s crystallization conditions is good. |
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