| With the development of 5G mobile communication technology,high quality factor,ultra-low dielectric constant and near-zero resonance frequency temperature coefficient dielectric ceramics are used as dielectrics for dielectric resonators,filters,antennas,substrates and other components in 5G/6G communication systems The use of materials has received widespread attention.Mg3B2O6?MBO?ceramic material has good microwave dielectric properties:?r=5.9,Q×f=48598 GHz,?f=–69.7 ppm/°C.On the basis of the synthesis of Mg3B2O6ceramics,the ceramics with positive temperature coefficient of resonance frequency are added to adjust the temperature coefficient of resonance frequency to near zero.The additives used in this paper are Ca Sn Si O5?CSSO,?r=9.08,Q×f=61000 GHz,?f=+35 ppm/°C?,Ca Ti O3?CTO,?r=160,Q×f=5000GHz,?f=+850 ppm/°C?,Ba3?VO4?2?BVO,?r=14,Q×f=42000GHz,?f=+52 ppm/°C?.The main research and summary analysis are summarized as follows:?1?Exploration of preparation technology of pure phase Mg3B2O6microwave ceramics.Since H3BO3 will evaporate in a high-temperature environment,the subject is to study the synthesis of pure phase under different levels of H3BO3.The analysis of XRD diffraction peaks found that the pure phase was prepared when the amount of H3BO3 was 20%.Phase Mg3B2O6ceramic material,and obtained good microwave dielectric properties:?r=5.9,Q×f=48598 GHz,?f=–69.7 ppm/°C.The refinement results indicate that Mg3B2O6ceramics are orthorhombic,with unit cell parameters?space group:Pnmn,a=5.398?,b=8.416?,c=4.497?,V=205.1?3,Z=2?.Finally,the Ca Sn Si O5ceramic with a positive temperature coefficient is used to adjust the temperature coefficient,but the Ca2Si O4 impurity phase is found in XRD,which cannot achieve the purpose of adjusting the temperature coefficient to make it near zero.?2?Near-zero temperature coefficient?1-x?MBO-x CTO composite ceramic preparation.Based on the synthesis of pure phase Mg3B2O6ceramics in the previous chapter,according to the law of temperature coefficient of composite ceramics,Ca Ti O3is added to adjust the temperature coefficient of resonance frequency of Mg3B2O6ceramics,and a set of?1-x?MBO-x CTO?x=7.2mol%,7.4mol%,7.6mol%,7.8mol%,8mol%?experiment.Combining XRD and EDS analysis,only the MBO and CTO ceramic phases and a small amount of Mg O phase were found in the composite ceramics,and no other phases were found.Combined with DSC thermogravimetric analysis,it is understood that there will be no reaction between the two ceramics,and at a temperature of 1000?,Mg3B2O6will melt,and Ca Ti O3 may be converted from monoclinic system to orthorhombic system at 1080?.Combined with the analysis of SEM and EDS,it is known that there are no other phases in the high temperature process.When x=7.2%,the maximum Q×f value is obtained.At this time,the microwave dielectric performance is:?r=6.66,Q×f=36634 GHz,and?f=-2.0 ppm/°C.When x=7.4%,a near-zero temperature coefficient of resonance frequency is obtained.At this time,the microwave dielectric performance is:?r=6.67,Q×f=35130 GHz,and?f=-0.7 ppm/°C.?3?Preparation of near-zero temperature coefficient?1-x?MBO-x BVO composite ceramics.The problem of Experiment 2 is that the Q×f value of Ca Ti O3 ceramic is only5000 GHz,which will lower the Q×f value of the composite ceramic.In contrast,Ba3?VO4?2 ceramic has a positive temperature coefficient and a large Q×f value and low sintering temperature.On the basis of Experiment 1,?1-x?MBO-x BVO?x=51mol%,53mol%,55mol%,57mol%,59mol%?was weighed according to the chemical formula.Combined with XRD,it is known that there are only MBO phase and BVO phase in the composite ceramic,which proves that there is no reaction between the two.Combined with SEM and EDS elemental analysis,when the addition amount is 51%,there is BVO phase in the composite ceramics.As the BVO content continues to increase in the later period,the composite ceramics are more in the form of solid solutions.When x=51%,the maximum Q×f value is obtained,the microwave dielectric performance is:?r=8.5,Q×f=44831 GHz,?f=-11.3 ppm/°C.When x=57%,the obtained Near-zero temperature coefficient of resonance frequency,microwave dielectric properties are:?r=8.8,Q×f=45424 GHz,?f=+1.2 ppm/°C,which not only increases the Q×f value,but also adjusts the temperature drift Lowering the sintering temperature of ceramics has great research significance.This series of ceramics has application prospects in 5G ceramic dielectric filters,antennas,substrates and other components. |
PDF Full Text Request