Al2O3掺杂对Ba4Sm9.33Ti18O54陶瓷显微结构和介电性能的影响

摘要

采用固相反应法制备了Ba4Sm9.33Ti18O54(简称BST)·xwt％Al2O3(x=0～1.5)微波介质陶瓷.研究了掺杂Al2O3对BST陶瓷的显微结构和介电性能的影响.扫描电镜和能谱分析结果显示:未掺杂的BST陶瓷中有少量Sm2Ti2O7相,随着增加Al2O3掺入量,Sm2Ti2O7相消失,BST陶瓷中先后产生了BaTi4O9(x≥0.6)和BaAl2Ti5O14(x≥1.0)两种新相.介电性能测试结果表明Sm2Ti2O7相的消失以及少量BaTi4O9相的形成,能显著提高BST陶瓷的Qf值,但会降低陶瓷的介电常数.当Al2O3的掺入量从0.6wt％增加到1.0wt％时,BaTi4O9相的量逐渐增加,引起BST陶瓷的Qf值略微下降.BaAl2Ti5O14相的产生会同时降低BST陶瓷的介电常数和Qf值.掺入0.6wt％Al2O3的BST陶瓷在1340℃烧结3h后具有最佳的介电性能:εr=74.7,Qf=10980GHz,rf=-11.8× 106/℃.%Ba4Sm9.33Ti18O54 (BST) · xwt%Al2O3 (x=0-1.5) microwave dielectric ceramics were prepared by solid state reaction method. The effects of A12O3 on the microstructure and dielectric properties of BST ceramics were studied. With the increasing amount of A12O3, the Sm2Ti2O7 phase observed in the undoped BST ceramics disappeared and new phases BaTi4O9 (x≥0.6) and BaAl2Ti5O14 (x ≥1.0) were found in BST ceramics successively as identified by SEM and EDS analysis. It was showed that the disappearance of Sm2Ti2O7 phase and the formation of a small amount of BaTi4O9 phase significantly improved the Qf values of the BST ceramics, at the cost of dielectric constant. Further increasing the amount of A12O3 produced more BaTi4O9 led to a slight decrease in Qf values. However, both the dielectric constant and Qf values were deteriorated with the appearance of BaAl2Ti5O14. BST ceramics with 0.6wt% A12O3 doped sintered at 1340℃ for 3 h obtained the best dielectric properties: εr=74.7, Qf =10980 GHz, ΤF= -11.8×l0-6/℃.