Low Temperature Sintering Of Bao-tio <sub> 2 </ Sub> Department Of Ceramic Materials

In recent years, the information capacity of mobile communications has a rapid growth. Therefore, Mobile communications must move towards higher frequencies and the demand for miniaturization of passive components has become increasingly urgent. The only way to achieve further miniaturization of mobile communication terminal is multilayer chip components. However, it requires microwave materials to co-fire with high conductivity metal electrodes and the best metal electrodes have low melting point, like Ag (td = 960℃) or Cu (td = 1060℃) and so on. Thus, the research and development of low-temperature sintering microwave dielectric ceramics has become a focus and direction.In this paper, the first step is obtaining the compound which have good microwave dielectric properties in the BaO-TiO2 system, BaTi₄O₉ and Ba4Ti₁₂O₂₇, respectively, and their optimum pre-firing temperature. Due to the sintering temperature of BaTi₄O₉ and Ba4Ti₁₂O₂₇ at 1300℃, They are far from meeting the requirements of low-temperature cofiring. So it is necessary adding sintering aids to lower their sintering temperature. The effect of ZnO on the sintering temperature and microwave dielectric properties of BaTi₄O₉ and Ba4Ti₁₂O₂₇ was investigated. The decrease of sintering temperature is mainly upon the formation of second phase. The Ba4Ti₁₂O₂₇ ceramics containing 11wt% ZnO sintering at 1100℃have good microwave dielectric properties ofεr=36.4,Q×f=14140GHz. The BaTi₄O₉ ceramics containing 9wt% ZnO sintering at 1600℃have good microwave dielectric properties ofεr=31.4,Q×f=12264GHz.Although ZnO has a good effect on the sintering temperature of the specimen, it has not yet reached the requirements co-firing with the Ag or Cu. So the effect of H3BO3 on the sintering temperature and microwave dielectric properties of BaTi₄O₉ and Ba4Ti₁₂O₂₇ was investigated. The decrease of sintering temperature is mainly up to the formation of BaB₂O₄ . The Ba4Ti₁₂O₂₇ containing 3wt% H3BO3 sintering at 950℃have good microwave dielectric properties ofεr=34.1, Q×f=9000GHz. The BaTi₄O₉ ceramics containing 2wt% H3BO3 sintering at 980℃also have good microwave dielectric properties ofεr=31.5, Q×f=15000GHz. After that, to get better results, the effect of H3BO3 and CuO on the sintering temperature and microwave dielectric properties of Ba4Ti₁₂O₂₇ was investigated. The decrease of sintering temperature is mainly up to the formation of BaCu(B2O5) . The Ba4Ti₁₂O₂₇ ceramics containing 3wt% H3BO3 and 5mol% CuO sintering at 900℃have good microwave dielectric properties ofεr=32.2, Q×f=8573.8GHz.At last, the effect of some other sintering aids on the sintering temperature and microwave dielectric properties of Ba4Ti₁₂O₂₇ was investigated. Owing to inhibiting Ti4+ into poor dielectric properties of Ti3+, the Ba4Ti₁₂O₂₇ can maintain good dielectric properties. The Ba4Ti₁₂O₂₇ containing 11wt% ZnO and 3wt% Nb2O5 sintering at 1140℃have good microwave dielectric properties ofεr=35.2, Q×f=9111GHz. The Ba4Ti₁₂O₂₇ containing 2wt% CuV2O6 sintering at 1130℃also have good microwave dielectric properties ofεr=37.5, Q×f=10512.8.