【作者】 陈磊；

【导师】 黄新友；

【作者基本信息】 江苏大学 ， 材料学， 2017， 硕士

【摘要】 随着电子技术飞速发展,对于介电材料的介电性能（如介电常数、介电损耗、容温特性等）要求越来越高,（Ba,Sr）TiO₃基介电陶瓷材料作为常用的电容器陶瓷材料,纯的BST介电材料的介电常数随温度变化较大,为满足应用要求必须对其进行掺杂改性。本文通过在BST中掺杂几种典型的离子化合物,以BST为主晶相基体,采用传统固相法制备工艺,借助XRD,SEM,高低温介电温谱仪,LCR电桥等测试分析方法,分别研究在最佳烧结温度下,不同离子化合物的掺杂量对BST基电容器陶瓷介电性能的影响。研究发现:（1）化合物BaZrO₃、BaSnO₃、SrZrO₃掺杂对BST陶瓷有相似的改性作用。随着掺杂量的增加,试样的居里点均逐渐向负温方向移动,居里峰介电常数先增大后减小。BaZrO₃和BaSnO₃掺杂,BST陶瓷的介电常数均先增大后减小,介电损耗先减小后增大。当BaZrO₃掺杂量为6.0wt.%时,BST介电性能最佳,介电常数最大,为14479;介电损耗最小,为0.016;容温变化率为+19.97%^-79.79%。当BaSnO₃掺杂量为1.2wt.%时,BST介电性能最佳,介电常数最大,为14195;介电损耗最小,为0.0011。SrZrO₃掺杂,试样介电常数逐渐减小,介电损耗先减小后增大。当SrZrO₃掺杂量为6.0wt.%时,BST陶瓷的介电损耗最小,为0.0168。（2）CaSnO₃掺杂,BST陶瓷的介电常数先减小后增大又再减小,介电损耗先减小后增大,居里点逐渐向负温方向移动,居里峰发生弥散。当CaSnO₃掺杂量为6.0wt.%时,BST介电性能最佳,介电常数为4963;介电损耗最小,为0.0069;容温变化率为+73.81%,-43.56%。（3）Bi₄Ti₃O₁₂掺杂,BST陶瓷的介电常数逐渐减小,介电损耗先减小后增大,居里点逐渐向负温方向移动,介电峰逐渐压低并展宽。当Bi₄Ti₃O₁₂掺杂量为1.6wt.%时,BST介电性能较好,介电损耗最小,为0.0068;介电常数为3744,容温变化率为+1.70%^-44.61%。Bi₂（SnO₃）₃掺杂,BST陶瓷的介电常数先增大后减小再又增大然后减小,介电损耗先减小后增大再减小。当Bi₂（SnO₃）₃掺杂量为2.5wt.%时,BST样品介电损耗最低,为0.0124;此时耐压最大为5.8KV/mm,介电常数为4171,电阻率为11.83×10¹⁰?·㎝。（4）La₂（ZrO₃）₃掺杂,随着掺杂量的增加,La³⁺在晶界偏析,晶粒得到细化。BST陶瓷的介电常数先大幅下降,后有小幅提升,之后又再下降;介电损耗先减小后增大再减小。La₂（ZrO₃）₃掺杂具有明显的移峰和压峰作用,居里峰随掺杂量增加弥散效应显著。（5）MgNb₂O₆掺杂,BST陶瓷的介电常数逐渐减小,介电损耗先增加后减小再增加,介电居里峰得到明显的压抑和展宽。MgNb₂O₆掺杂过程中,形成了SrNbO₆等杂相,容温曲线出现双峰现象。掺杂试样容温特性较佳,最小容温变化率为+0.17%^-28.19%。更多还原

【Abstract】 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:ε_r of 3744,tanδof 0.0068,ΔC/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,ε_r of 4147,ρof 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 minimumΔC/C of+0.17%^-28.19%.更多还原