Research On Preparation And Microwave Dielectric Properties Of Medium And Low Dielectric Constant Microwave Dielectric Ceramics

With the development of 5G technology,microwave dielectric ceramics have become an indispensable electronic component material in 5G communication technology.Compared with the traditional 4G communication technology,the materials required for5G communication technology need to meet the basic performance requirements of high frequency band and even millimeter wave transmission.Microwave dielectric ceramics have become an important basic material in the development of 5G,because of its easy to realize large-scale,high-frequency and other characteristics.Among them,the microwave dielectric ceramic materials with the hottest researched and most widely used are mainly focused on the low and medium dielectric constant.In this paper,ceramic powders were prepared by traditional solid-phase reaction methods,and a series of microwave dielectric ceramics with excellent microwave dielectric properties were successfully prepared by doping,substitution and adjustment of stoichiometric ratios using BaTi₄O₉-Ba₂Ti₉O₂₀and Mg₂SiO₄+CaTiO₃series ceramics as research objects.The effects of different modification methods on the sintering performance,microscopic morphology and microwave dielectric properties of the ceramics of different systems were investigated in depth.The research results are as follows:（1）BaO-xTiO₂-0.5wt%CeO₂（x=4.15～4.45）component ceramics were prepared by solid-phase reaction method.BaTi₄O₉-Ba₂Ti₉O₂₀complex ceramic substrates with good microwave dielectric properties were successfully obtained by varying the x-value（different Ba/Tiratios）.the Ba/Tiratio determined the phase composition and content.As the value of x increases,theε_rof the multiphase ceramic material increases and the Q×f values andτ_fvalues decrease.At x=4.15,the multiphase ceramic sintered at 1300℃ for 3h has excellent microwave dielectric properties:ε_r=38.33,Q×f=49,750 GHz andτ_f=+12.87 ppm/℃.（2）Based on（1）BaO-4.15TiO₂-0.5 wt%CeO₂/x WO₃（x=0-0.09）component ceramics were prepared using a conventional solid-phase reaction method.By varying the x value（WO₃content）,BaTi₄O₉-Ba₂Ti₉O₂₀Composite ceramics materials with good microwave dielectric properties were successfully obtained.the WO₃content determined the composition and content of the phases,and theε_randτ_fvalues gradually decreased with increasing WO₃content,and the Q×f value increased and then decreased.The best microwave dielectric properties were obtained at x=0.07 and sintered at 1325℃ for 3h:ε_r=37.81,Q×f=51,531GHz andτ_f=+3.33ppm/℃.（3）Microwave dielectric ceramics with 0.9Mg_2+xSiO_4+x-0.1CaTiO₃（x=0,0.025,0.05,0.075,0.1,0.2）were prepared by the solid phase reaction method.the Mg O content determined the presence of the secondary phase.Moderate additions of Mg O could promote sintering and reduce porosity.With the increasing addition of Mg O,theε_rand Q×f values of the composite ceramic material gradually increased,and theτ_fvalue increased and then decreased.At x=0.075,the best microwave dielectric properties were obtained by sintering at 1425℃ for 3 h:ε_r=9.78,Q×f=68,048 GHz andτ_f=+4.57 ppm/℃.（4）A series of Microwave dielectric ceramics with Mg₂SiO₄-Ca_1-xSm_2x/3TiO₃were prepared by solid-phase reaction method.The effects of Ca_0.8Sm_0.4/3TiO₃content on the physical phase composition,sintering properties and microwave dielectric properties of（1-x）Mg₂SiO₄+x Ca_0.8Sm_0.4/3TiO₃（x=0.21～0.24）were investigated.The Ca_0.8Sm_0.4/3TiO₃content determined the presence of secondary phases.With the increasing addition of Ca_0.8Sm_0.4/3TiO₃,theε_randτ_fvalues of the composite ceramic material increased,while the Q×f value decreased.At x=0.22,the best microwave dielectric properties were obtained by sintering at 1325℃ for 3 h:ε_r=11.89,Q×f=32,703 GHzτ_f=+0.49 ppm/℃.（5）0.8Mg₂SiO₄+0.2Ca_0.9Sm_0.2/3Al_2x/3Ti_1-xO₃（x=0～0.25）microwave dielectric ceramics were prepared by the solid-phase reaction method.The amount of Al³⁺substitution determined the phase composition.ε_rand Q×f values were influenced by the amount of Al³⁺substitution,whileτ_fvalues were highly dependent on the phase composition.With the increasing Al³⁺content in the ceramics,theε_randτ_fvalues gradually decreased and the Q×f value gradually increased.The best microwave dielectric properties were obtained at x=0.2 and sintered at 1410℃ for 3 h:ε_r=10.69,Q×f=70,769 GHz andτ_f=-0.66 ppm/℃.