Study On Preparation Methods And Microwave Dielectric Properties Of Medium And Low Dielectric Microwave Dielectric Ceramics

With the rapid development of science and technology,the popularity of communication technology has been popularized.,which greatly changes people's lives.The microwave dielectric properties of ceramics have always been the focus of scholars'research and attention.Medium and low dielectric constant ceramics have been widely studied and applied.Compared with the high dielectric constant materials,medium and low ceramics generally have high Q value,searching for ceramics with good thermal stability,low cost and simple process become the the main research directions.In this paper,serials of microwave dielectric ceramics with low and medium dielectric constant materials with excellent microwave dielectric properties and compact microstructures were successfully prepared by doping,adjusting composition and sintering processes.?1?2.5ZnO-?5-x?TiO_2-x ZrO₂-2.5Nb₂O₅?0.2?x?0.4??ZTZN?ceramics were successfully prepared by a solid-state reaction method.XRD patterns show that ZTZN ceramics are composed of Zn_0.17Nb_0.33Ti_0.5O₂ and ZnTiNb₂O₈ phases.SEM images show that the density of ZTZN ceramics increases with the increase of sintering temperature and ZrO₂ content,while their bulk density,?_r value and?_f value increase with the increase of sintering temperature.In addition,Q×f value increases first and then decreases with the increase of sintering temperature.When x=3,ZTZN ceramics sintered at 1075? for 4 h showed excellent microwave dielectric properties with?_r=44,Q×f=30,155 GHz,?_f=0.89 ppm/?.?2?Porous Mg₃Al₂Si₃O₁₂ ceramics were successfully prepared by the solid-state reaction method.XRD patterns show that the main phase of ceramics isMg₂Al₄Si₅O₁₈,and MgSiO₃ and MgAl₂O₄ phases are the second phases.Mg₃Al₂Si₃O₁₂ ceramics exhibit good microwave dielectric properties as well as porous microstructural characteristics.When the sintering temperature is 1300?,the ceramics have the microwave dielectricproperties with ?_r=4.2,Q×f=24,529,?_f=-12.5 ppm/?.?3?LiCa₃ZnV₃O₁₂?LCZV?and NaCa₂Mg₂V₃O₁₂?NCMV?vanadium based garnet ceramics with compact microstructures were successfully prepared by a reaction-sintering method.The phase compositions,surface micromorphology,sintering characteristics and microwave dielectric properties of ceramics were studied and analyzed.The LCZV and NCMV ceramics prepared by reaction-sintering also show denser microstructure.When the sintering temperature is 875?,the bulk density of LCZV ceramics is 3.30 g/cm³,which is 98.16%of the theoretical density.At the same time,the LCZV ceramic also exhibits excellent properties with ?_r=6.9,Q×f=45,618 GHz,?_f=-39.6 ppm/?.When the sintering temperature is 825?,the NCMV ceramic exhibits excellent properties with?_r=7.1,Q×f=25,924 GHz,?_f=5.8ppm/?.?4?0.7CaTiO₃-0.3NdAlO₃?CNTA70?ceramics with compact microstructure were successfully prepared by the reaction-sintering method.The phase compositions,sintering characteristics and surface micromorphology of CNTA70 ceramics were studied and analyzed by XRD,SEM and EDS.The CNTA70 ceramics sintered at1525? for 4 h exhibite good microwave dielectric properties with ?_r=43.1,Q×f=31,144 GHz,?_f=5.2 ppm/?.