The Low Temperature Firing And Dielectric Properties Of Cblst Ceramic And Clnt Ceramic

With the rapid development of microwave communication, the low-cost and miniaturization of microwave components are demanded more and more. However low temperature co-fired ceramic technology (short of LTCC) has become the first-selected way for microwave components of low cost and miniaturization. It has widely used in military and civilian communication systems. Microwave dielectric ceramic is a new dielectric material, as the key material of LTCC technology. It has been widely used as the core microwave components in resonator, filter and antenna fields. In order to realize miniaturization and reduce the production costs, the microwave dielectric ceramics are required to be sintered with Ag or Cu at low temperature and high permittivity constant, low dielectric loss, near zero temperature coefficient of the resonance frequency. But the sintering temperature of most of dielectric ceramics is high, so lowing its sintering temperature to co-fire with Ag or Cu is to continue concern focusHighεr CaO-BaO-Li₂O-Sm₂O₃-TiO₂ (short of CBLST) and CaO-Li₂O-Nd₂O₃-TiO2 (short of CLNT) exhibit low dielectric loss and near zero temperature coficints, which make it the promising materials for the preparation of multilevel and small-sized components in microwave communications. So the CBLST and CLNT ceramic systems with excellent dielectric properties were eclected as the investigated objects. The effects of Li₂O-B₂O₃-SiO₂(short of LBS) and BaCu(B₂O₅) (short of BCB) complex additive on the dielectric properities of CBLST ceramic system, and BCB and ZBS seperate additives on the CLNT ceramic systems have been investigated in this paper. The relation of ceramic densifing, microstructure, phase composition and dielectric properities were analysed by XRD and SEM, and so on. The main research results are as follows:1. CBLST ceramic system with BCBand LBS complex additives BCB and LBS complex additives could low the sintering temperature of CBLST ceramics efficiently from 1325oC to 1050oC without changing two phases of CBLST ceramic. The relative density of 97.4% and excellent dielectric properties (ε_r=81.9, tanδ=0.0062,Ï„_f=-3.75ppm/oC) were obtained when CBLST ceramic with 6wt%BCB+0.5wt%LBS additive sintered at 1050oC for 2h, and the dielectric loss is lower than that of CBLST ceramic with 6wt%BCB.2. CLNT ceramic with BCB additiveBCB additive change the phase composition of CLNT ceramics and form the new phase, and decrease the sintering temperature of CLNT ceramic from 1200oC to 950oC. 96.8% of the theoretical density and good dielectric properties (ε_r=94.03, tanδ=0.0097,Ï„_f=1.076ppm/ oC, at 1MHz ) could obtained when CLNT ceramic with 5wt%BCB additive sintered at 950 oC for 2h3. CLNT ceramic with ZBS additiveZBS additive could low the sintering temperature of CLNT ceramic from 1200oC to 925oC, and 97.2% of the theoretical density and excellent dielectric properties ofεr=95.21, tanδ= 0.01,Ï„f =6ppm/ oC were obtained when CLNT ceramic sintered at 925oC for 2h. Inaddition into perovskite, a few of Nd₂Ti₂O₇ phase were detected.