Study On Structure And Microwave Dielectric Properties Of BYS/YMAS/YZAS Silicate Ceramics

With the development of modern communication technology,preparation of microwave ceramic materials with low dielectric constant,high quality factor and near zero temperature coefficient of resonant frequency has become a research focus in recent years.In this paper,Ba₉Y₂Si₆O₂₄（BYS）ceramics,La_3-xY_xMgAl₃SiO₁₂(L_3-xY_xMAS)（x=0,1,2,3）ceramics and Y₃ZnAl₃SiO₁₂（YZAS）ceramics were synthesized by solid state reaction process.The phase composition,crystal structure surface morphology were analyzed by XRD,Rietveld structure refinement,SEM EDS.Microwave dielectric properties were tested by resonator method.The main results obtained are listed as follow:（1）BYS ceramics were synthesized by solid state reaction process.The results of XRD test show that pure BYS ceramics were obtained by solid state reaction process.Rietveld refinement of powder diffraction data suggested that BYS belongs to the trigonal structure with space group of R-3,a=b=10.0402（2）?,c=22.1942（6）?.The microwave dielectric properties of BYS ceramics showed a strong positive correlation with sintering density.When the sintering temperature was 1400℃,bulk density is 4.9473 g/cm3,reached 94.6% of the theoretical density.And the microwave dielectric properties were: a dielectric constant（εr）of 14.9,a quality factor（Q×f）of 22444.2 GHz（@8.43 GHz）,and a temperature coefficient of resonant frequency（τ_f）of +35.8 ppm/℃.（2）L3-xYxMAS（x=0,1,2,3）ceramics were synthesized by solid state reaction process.The results of XRD test showed that pure cubic Y₃MgAl₃SiO₁₂（YMAS）ceramics are obtained when x is 3.Rietveld refinement of powder diffraction data suggested that YMAS belongs to the cubic structure with space group of Ia-3d,a=b=c=12.0548（0）?.YMAS ceramics sintered at 1550℃ for 4h exhibited best microwave dielectric properties: εr=10.1,Q×f= 57337.2 GHz（@9.59 GHz）,τ_f=-31.9 ppm/℃.（3）YZAS ceramics were synthesized by solid state reaction process.The Y₂SiO₅ second phase were detected by XRD tests.Rietveld refinement of powder diffraction data suggested that YZAS belongs to the cubic structure with space group of Ia-3d,a=b=c=12.0581（0）?.The YZAS ceramics sintered at 1500℃ for 4h exhibited good microwave dielectric properties: εr=10.2,Q×f= 37938.2 GHz（@9.47 GHz）,τ_f=-31.7 ppm/℃.