Study On Dielectric Property Of Compounds Doped BST Based Capacitor Ceramics

With rapid development of electronic technology,the requirements on the dielectric properties of dielectric material such as the dielectric constant,dielectric loss and characteristics of capacitance-temperature become higher.?Ba,Sr?TiO₃ based dielectric ceramic materials are commonly used as ceramic capacitor.While dielectric constant of pure dielectric BST materials changes greatly with variable temperature.To meet application requirements,the BST could be modified by doping.In this paper,several typical ions compounds are chosen to dope into the BST as the host crystalline phase by traditional solid phase method.The influence of doping amount of ionic compounds on dielectric performance of BST capacitor ceramics is analyzed by means of XRD,SEM,high and low temperature dielectric spectrometer,LCR bridge method.The optimum sintering temperature is also obtained.The study shows that:?1?The compounds of BaZrO₃,BaSnO₃ and Sr ZrO₃ have similar modification effect on doped BST ceramics.With the increase of doping amount,the Curie temperature of the BST ceramic samples decreases gradually,dielectric constants under curie peak firstly exhibit a upwards trend and then turn downwards.When the BST ceramic is doped with BaZrO₃ and BaSnO3,the dielectric constants of BST ceramics increase firstly with the doping and then decrease,while the dielectric loss changes in an opposite way,it decreases firstly and then increases.When the doping amount of BaZr O3 is 6.0wt.%,BST shows the best dielectric performance.Dielectric constant of BST with the largest value of 14479 is obtained,as well as the minium Dielectric loss with the value of 0.016.The change rate of capacitance-temperature is between+19.97%and-79.79%.When the doping amount of BaSnO3 is 1.2wt.%,BST ceramics shows the best dielectric performance.The largest dielectric constant is 14195.The minimum dielectric loss is 0.0011.Dielectric constant of BST doped with SrZrO3 decreases gradually.Dielectric loss of BST doped with SrZrO₃ decreases firstly,and then increases.When the doping amount of SrZrO₃ is 6.0wt.%,the minimum dielectric loss of BST with the value of0.0168 is obtained.?2?The dielectric constant of BST ceramics decerases firstly,then increases and finally decreases,while the dielectric loss decreases firstly and then increases with the increasing doping amount.Curie point of BST gradually moves downwards and the Curie peak shows dispersion characterization with the increasing CaSnO₃ doping amount.When the doping amount of CaSnO₃ is 6.0wt.%,BST shows the best dielectric performance,with the dielectric constant of 4963 and the minimum dielectric loss of 0.0069.The change rate of capacitance-temperature is between+73.81%and-43.56%?3?The dielectric constant of BST ceramics decreases gradually,dielectric loss decreases firstly and then increases,Curie point gradually moves downwards,and the shape of dielectric peak becomes broadened and lowered with the creasing doping amount.When the doping amount of Bi₄Ti₃O₁₂ is 1.6wt.%,BST achieves its best properties:?_r of 3744,tan?of 0.0068,?C/C of+1.70%^-44.61%.The dielectric constant of BST ceramics increases firstly,then decreases and increases again,and finally decreases,while the dielectric loss firstly decreases then increases and finally decreases with the increasing Bi₂?SnO₃?₃ doping amount.When the doping amount of Bi₂?SnO₃?₃ is 2.5wt.%,BST achieves its minimum dielectric loss of 0.0124,maximum E_b of 5.8KV/mm,?_r of 4147,?of 11.83×10¹⁰?·?.?4?When BST is doped with La₂?ZrO₃?₃,La³⁺gets segregation in the grain boundary and the grain size is refined.The dielectric constant of BST ceramic samples decreases rapidly at first,increase slightly and then falls down again,while the dielectric loss decreases firstly and then increases and finally decreases with the increasing doping amounts of La₂?ZrO₃?₃.La2?ZrO3?3 can obviously change the location of the peaks and lower their height.A remarkable dispersion effect on the Curie peak is observed when La₂?ZrO₃?₃ is doped.?5?The dielectric constant of BST ceramic decrease gradually,and the dielectric loss increases firstly then decreases and finally increases finally with the increasing MgNb₂O₆doping amount.In Mg Nb₂O₆ doping process,SrNb₂O₆ and some unknown phases are formed.Capacitance-temperature curves show bimodal phenomena.The BST samples doped with MgNb₂O₆ achieve better Capacitance-temperature properties and with minimum?C/C of+0.17%^-28.19%.