Low Temperature Sintered ZMT Dielectric Ceramics And Its Application

With the increasing demand for microwave products such as radar,satellite and mobile phones,the related research fields of microwave materials and devices have received more and more attention in recent years.Low temperature co-fired ceramic?LTCC?technology can meet the requirements of miniaturization,high density,multi-function and high reliability of electronic devices,and is an electronic packaging technology with obvious advantages and great potential.Among LTCC technologies,materials with appropriate dielectric constant,good temperature coefficient,and high quality factor are often used as microwave dielectric substrates,so it is imperative to study new LTCC substrate materials.(Zn_0.7Mg_0.3)TiO₃ microwave dielectric material have good microwave dielectric properties when sintered at low temperature,and have great potential in miniaturization of microwave devices.In order to further increase the practical value of ZMT microwave dielectric ceramics,this paper mainly improves the quality factor and temperature stability of ZMT microwave dielectric ceramics.Based on the existing research results of ZMT system,ZMT microwave ceramics was selected as the research object.Firstly,the temperature stability of ZMT ceramics was improved by Ca²⁺ion substitution,and LBSCA glass sintering agent was added to reduce the sintering temperature of ZMT ceramics to around 900°C.The effect of different amount of sintering aid on the phase composition,microstructure,density and microwave dielectric properties of ceramic materials was analyzed.The experimental results show that the best effect is obtained by doping 2wt%of LBSCA glass.Then,ZMT ceramics and different doses of Li₂TiO₃ ceramics are combined.It is hoped that in this way,composite ceramics with temperature coefficient close to zero and good microwave dielectric properties can be obtained.In the experiment,LBSCA glass is used as a sintering aid to reduce the composite ceramics.The sintering temperature is about 900°C.The above two schemes can effectively adjust the temperature coefficient of ZMT ceramics,but the quality factor is reduced.In order to improve the quality factor of ZMT ceramics,different content of Co ions were used to replace Zn ions and Mg ions to reduce the dielectric loss of ZMT ceramics.In the experiment,1wt%LBSCA glass was used as a sintering aid to reduce the sintering temperature.The experimental results show that when the ceramic samples are sintered at 900^oC and the value of x is 0.075,the microwave performance of(Zn_0.7Mg_0.3)_1-xCo_xTiO₃ material is optimal:?_r=21.602,Q×f=80040GHz,?_f=-70.24 ppm/°C.After that,this paper uses LMZBS glass as a sintering aid to explore whether the quality factor of(Zn_0.7Mg_0.3)_0.925Co_0.075TiO₃ ceramic material can be further optimized.When the content of LMZBS glass is 1.5wt%,the experiment achieves the best result:?_r=17.276,Q×f=63500 GHz,?_f=-67.12 ppm/°C.Obviously,the above two sets of experiments have effectively improved the quality factor of ZMT ceramic materials,but the temperature stability is still not ideal.Therefore,at the end of this paper,(Zn_0.7Mg_0.3)_0.925Co_0.075TiO₃ ceramics were combined with Li₂TiO₃ ceramics to obtain composite ceramics with temperature coefficient close to zero.The experimental results show that when the doping amount of LBSCA glass is1.5wt%,the microwave dielectric properties of composite ceramics are good:?_r=18.125,Q×f=44200 GHz,?_f=12.7 ppm/°C.In the aspect of antenna simulation,this paper designs a 100*110*0.73mm planar eight-eye antenna based on 0.32(Zn_0.7Mg_0.3)_9.925Co_0.075TiO₃-0.68Li₂TiO₃ two-phase composite ceramic material.Results of simulation showed that the center frequency of the antenna was 1.51GHz,the bandwidth was 160 MHz,the peak gain achieved 6.5 dBi,the polarization mode was linear polarization,the simulation result meets the requirements of the index.