Ca_(0．3)(Li_(1/2)Sm_(1/2))_(0．7)TiO_3微波介质陶瓷的低温烧结研究

Research on Low-temperature Sintering of Ca_(0.3)(Li_(1/2)Sm_(1/2))_(0.7)TiO_3 Microwave Dielectric Ceramics

采用传统陶瓷制备工艺,制备了掺杂Na_2O-CaO-B_2O_3(NCB)氧化物的Ca_(0.3)(Li_(1/2)Sm_(1/2))_(0.7)TiO_3(CLST)陶瓷,研究了NCB掺杂量与晶相组成、显微结构、烧结性能及微波介电性能的关系.研究结果表明:复合氧化物NCB掺杂量在1wt%～15wt%范围内没有杂相生成,晶相仍呈斜方钙钛矿结构.随着NCB添加量的增加,陶瓷致密化温度和饱和体积密度降低,介电常数ε~r、无载品质因数与谐振频率乘积Qf值也呈下降趋势,频率温度系数T_f向正方向增大.NCB氧化物掺杂能有效地将CLST陶瓷的烧结温度由1300℃降低至900℃.添加12.5wt%NCB的CLST陶瓷在低温900℃烧结5h仍具有良好的微波介电性能:ε_r=73.7,Qf=1583GHz,T_f=140.1×10^(-6)/℃,满足高介多层微波器件的设计要求.

The NCB（Na2O-CaO-B2O3）-doped Ca（0.3）（Li（1/2）Sm（1/2））（0.7）TiO3（CLST）ceramics were fabri- cated via the traditional ceramic process.The relation between NCB dopant contents and the crystal structure,microstructure,sintering behavior,and dielectric properties of CLST ceramics were inves- tigated systematically.The results indicate that the second phases are not found when NCB dopant contents are in the range from 1wt% to 15wt% and the major phase of CLST ceramics is still orthorhom- bic perovskite.With the increase of NCB content,the densification temperature and bulk density of CLST ceramics decrease,the dielectric constantεr and the product of quality factor and resonance frequency Qf value also decrease,and the temperature coefficient of resonant frequencyτf increases to positive.NCB can effectively decrease the sintering temperature of CLST from 1300℃to 900℃. The sample of CLST with 12.5wt% NCB sintered at 900℃for 5h still has excellent dielectric proper- ties：εr=73.7,Qf=1583GHz,τf=140.1×10（-6）/℃,which satisfies the design demand of high dielectric constant and multilayer microwave components.