CaLa_4Ti_4O_(15)微波介电陶瓷的制备和性能(英文)

SYNTHESIS AND PROPERTIES OF CaLa_4Ti_4O_(15) MICROWAVE DIELECTRIC CERAMICS

采用固相法制备了CaLa4Ti4O15系微波介质陶瓷,研究了不同预烧温度对CaLa4Ti4O15陶瓷烧结特性和微波介电性能的影响。在1 200℃预烧CaLa4Ti4O15粉末,除CaLa4Ti4O15主相外,还存在部分CaTiO3,La2Ti2O7和La2TiO5混合相。在1 300℃和1 400℃预烧后,获得了六方类钙钛矿CaLa4Ti4O15单相。CaLa4Ti4O15粉末预烧后可烧结成高致密陶瓷(相对密度约97%),同时具有高机械品质因数与谐振频率的乘积(Q×f)值和近零谐振频率温度系数(τf)。1 550℃烧结的CaLa4Ti4O15陶瓷具有优异的微波介电性能:相对介电常数εr=45.1,Q×f=46 087 GHz,τf=-14.1×10-6/℃(预烧温度1 200℃);εr=45.9,Q×f=48 871 GHz,τf=-14.4×10-6/℃(预烧温度1 300℃)。

Microwave dielectric ceramics of CaLa4Ti4O15 were prepared by the solid-state reaction method. The influence of the calcining temperature on the sintering behavior and microwave dielectric properties was investigated. For the specimen calcined at 1 200 ℃, CaTiO3, La2Ti2O7 and La2TiO5 mixed phases were observed in addition to the CaLa4TiaO15 phase, while the hexagonal perovskite single phase was achieved for the CaLa4Ti4O15 powders calcined at 1 300℃ or 1400℃. CaLaaTi4O15 ceramics were sintered well with high relative density of about 97%. On the other hand, the ceramics had a high mechanical quality factor plus resonant frequency （Q×f） value and near zero temperature coefficient of resonant frequency （τf）. The CaLa4Ti4O15 ceramics sintered at 1550 ℃ exhibited excellent microwave dielectric properties as follows： relative dielectric constant εr=45.1,Q×f=46 087 GHz,τf=-14.1×10^-6/℃ and εr=45.9,Q×f=48 871 GHz,τf=-14.4×10^-6/℃for the specimens calcined at 1 200 ℃ and 1 300℃, respectively.