A Study On ZrTiO₄-Zn_0.5Ti_0.5NbO₄ Ceramics With Temperature Stability And Their Low Temperatute Sintering

The microwave dielectric ceramic materials need to meet the rapid development of modern communication technology,in which ZrTiO₄ based microwave dielectric ceramic materials have attracted wide attention because of their excellent properties.ZrTiO₄ has a very broad prospect in the fields of resonator,microwave base station and military radar.Researchers mainly focus on modifying ZrTiO₄ based ceramics by doping.Therefore,this article uses ZrTiO₄ ceramics as the research object,and adjusts its microwave dielectric properties by doping different proportions of Zn_0.5Ti_0.5NbO₄.In addition,when ZrTiO₄ powder is prepared by the traditional solid-phase reaction method,the sintering temperature is high.Although doping of Zn_0.5Ti_0.5NbO₄can reduce the sintering temperature less,it is necessary to use an external glass sintering aid to reduce the sintering temperature to meet the requirements of the LTCC technology and achieve co-firing with Ag.Therefore,the main research content of this article includes the following parts:1.The two-phase composite of Zn_0.5Ti_0.5NbO₄ and ZrTiO₄ was carried out to prepare ceramic samples of x Zn_0.5Ti_0.5NbO₄-（1-x）ZrTiO₄（0.1≤x≤0.5）.The relationship between the evolution of the crystal structure and the dielectric properties was discussed using Rietveld refinement and complex chemical bond theory.It was found that a solid solution of Zr_1-xZn_0.5xTi_1-0.5xNb_xO₄（0.1≤x≤0.5）was formed.Through doping Zn_0.5Ti_0.5NbO₄ into ZrTiO₄,theτ_f value has been adjusted to near zero.Excellent microwave dielectric performances withε_r=41.93,Q×f=26741GHz（f=5.8GHz）andτ_f=-2.3 ppm/℃are gained at x=0.2 sintered at 1250℃for 4 h.2.0.8ZrTiO₄-0.2Zn_0.5Ti_0.5NbO₄（0.8ZT-0.2ZTN）was selected as the sintering reducing ceramic system,and different components LBS glass were used as the sintering aids to research the melting temperature of LBS glass with different formulations,and the effect on the sintering reducing performance and microwave dielectric properties of 0.8ZT-0.2ZTN.it is found that the higher the proportion of Li₂CO₃,the lower the melting temperature of glass,and the appropriate increase in the content of SiO₂ in glass can improve the dielectric properties.The melting temperature of mixed Ca CO₃ and Al₂O₃ modified LBS glass will be further reduced.Combined with all aspects of the performance,LBS（G24）glass performance is more excellent.3.The effects of different content of G24 on the sintering reduction,crystal phase composition and surface morphology of 0.8ZT-0.2ZTN ceramics were studied.The glass phase in the sample makes the dielectric loss become very large,which will seriously destroy the microwave dielectric properties of ceramics.Considering various parameters,when the doping amount of G24 is 2wt.%,the best dielectric performance is obtained when sintered at 1025℃for 4h:ε_r=37.14,Q×f=12057GHz（f=6.0GHz）,τ_f=-0.25ppm/℃.4.With different content of Ba Cu（B₂O₅）（BCB）as sintering aids,The effects of different content of BCB on the sintering reduction,crystal phase composition and surface morphology of 0.8 ZT-0.2ZTN ceramics were studied.When there’s too much liquid,Zn will be enriched in the liquid phase,Zn₃Ti₂O₈ phase was formed from liquid phase during ceramic sintering.When the BCB content is 2wt.%,the best microwave dielectric properties obtained by sintering at 1050℃for 4h are:ε_r=40.18,Q×f=20059GHz（f=6.1GHz）,τ_f=8.39 ppm/℃.5.To further improve the microwave dielectric properties of ceramics that have been sintered by G24 glass,both G24 glass and BCB were used as sintering aids to study the effect of composite doped glass on the sintering properties of 0.8ZT-0.2ZTN ceramics.G24 glass and BCB composite sintering aid has a lower melting point than G24 and BCB,so the use of LBS（G24）glass and BCB composite sintering aid further reduces the temperature of the liquid phase,So that it can form a liquid sintering mechanism at lower temperature to promote sintering.Comprehensive parameters,when doped with 2wt.%G24 and 2wt.%BCB,the best dielectric properties can be obtained at 1000℃for 4 hours:ε_r=37.38,Q×f=13014 GHz（f=6.2GHz）,τ_f=-0.11ppm/℃.