The Research On Microwave Dielectric Properties Of Li₂Mg₃TiO₆ Ceramics

Microwave dielectric ceramics with low?_r,high Q and near zero temperature coefficient are widely used in telecommunications and radar communication applications.The Li₂Mg₃BO₆?B=Ti,Sn,Zr?microwave dielectric ceramics with surface core cubic rock salt structure have higher Q×f value?62490GHz¹68300 GHz?and lower sintering temperature.Microwave dielectric ceramic material.Although this ceramics have a higher Q×f value,and the dielectric constant is less than 20,the absolute value of the temperature coefficient of the resonant frequency is still larger.A series of Li₂Mg₃TiO₆?M=Mg,Zn,Co,Ca?microwave dielectric ceramics were prepared by the one-step synthesis method.The effects of the types and content of doping ions on the sintering behavior,phase composition,microstructure and microwave dielectric properties of microwave dielectric ceramics were systematically discussed.The main conclusions are as follows:The main crystalline phases were Li₂Mg₃TiO₆ when different ions were doped,and Mg₂TiO₄ impurity phase formed in the samples mixed with Mg.The phase CaTiO₃was found in the ceramics with Ca,which can coexist with Li₂Mg₃TiO₆ and form a stable composite system,so the performance is obviously better than others.After reducing the prefiring temperature from 1000 to 950?,The apparent porosity of ceramic samples increased,the dielectric constant decreased,the quality factor rised obviously,the experimental properties was improved totally.The line shrinkage,bulk density and quality factor all increased first and then decreased with the increase of doping content of Zn.We obtained the best performance at x=0.15:?_r=16.22,Q×f=37800 GHz,?_f=-45 ppm/??With the add of Ca content,the intensity of CaTiO₃ phase increased.The line shrinkage,bulk density and quality factor all increased first and then decreased.The temperature coefficient of the resonant frequency of the sample sintered at 1370?was zero?x=0.06?.The ceramic dielectric samples sintered at 1310?for 6h exhibited the best dielectric properties:?_r=17.42,Q×f=840650 GHz,and?_f=-19 ppm/?.The absence of Mg was beneficial to obtain Li₂Mg₃TiO₆.When Mg/Li=2.95/2,the best performance was obtained:?_r=14.48,Q×f=85357 GHz,?_f=-22 ppm/?.