烧结性能和介电性能的影响
(南京工业大学 材料科学与工程学院，南京 210009)
摘 要: 采用传统固相反应法制备Ba6−3x(La1−mBim)8+2x(Ti0.95Zr0.05)18O54(x=2/3)微波介质陶瓷，研究Bi掺杂对Ba6−3xLa8+2x(Ti0.95Zr0.05)18O54(x=2/3)陶瓷的烧结性能、微观结构以及介电性能的影响。结果表明：当0＜m＜0.4时，Bi3+取代A1位的La3+生成单相类钨青铜型固溶体；当Bi3+的掺杂量超过这个范围时，La0.176Bi0.824O1.5作为第二相出现在固溶体中；Bi3+的掺入使Ba6−3xLa8+2x(Ti0.95Zr0.05)18O54(x=2/3)陶瓷的烧结温度从1 400 ℃降低到1 300 ℃，同时，其介电常数大幅度提高，谐振频率温度系数减小，但品质因数急剧减小；当m=0.05时，1 350 ℃下保温 2 h烧结获得的陶瓷具有微波介电性能，εr=88.63，Q·f=4 395 GHz，τf=6.25×10−6/℃。
关键字: 介电性能；Bi掺杂；微波介质陶瓷；类钨青铜结构
（College of Materials Science and Engineering, Nanjing University of Technology, Nanjing 210009, China）
Abstract:The sintering properties, microstructures and dielectric characteristics of Ba6−3x(La1−mBim)8+2x(Ti0.95Zr0.05)18O54 (x=2/3) microwave dielectric ceramics prepared by conventional solid-state route were studied. The results show that Bi3+ replaced La3+ into A1 rhombic sites and a single-phase solid solution with tungstenbronze-like structure formed in the range of 0＜m＜0.4. When Bi3+ content exceeds this range, a second phase of La0.176Bi0.824O1.5 appears in the solid solution. Bi doping can lower the sintering temperature of Ba6−3x(La1−mBim)8+2x(Ti0.95Zr0.05)18O54(x=2/3) ceramics from 1 400 ℃ to 1 300 ℃, while a significant improvement of dielectric constant is achieved. The temperature coefficient of resonant frequency (τf) decreases, and the quality factor (Q·f) rapidly decreases. When m=0.05, the optimal microwave dielectric characteristics are achieved as εr=88.63, Q·f=4 395 GHz, τf=6.25×10−6/℃.
Key words: dielectric property; Bi doping; microwave dielectric ceramics; tungstenbronze-like structure
