Microwave dielectric properties of BaO-TiO2-WO3 ceramics sintered with glasses

The microwave dielectric properties and the sintering behavior of commercial BaO-TiO₂-WO₃ dielectrics, N-35, with addition of various glasses; (1) simple glass formers, (2) ZnO-B₂ O₃ based, (3) B₂O₃-SiO₂ based and (4) Al₂O ₃-SiO₂ based glasses were studied. The Q of N-35 sintered with a ZnO-B₂O₃ glass system showed a sudden drop in the sintering temperature to around 1000°C. Results of XRD, thermal analysis and scanning electron microscopy suggest that the chemical reaction between N-35 and the glass had a larger effect on Q than density. A 5wt% addition of B₂O₃ to N-35, when sintered at 1200°C, had the best dielectric properties, Q=8300 and K=34.1 at 8.5 GHz, among the glasses Q, K and density increased with sintering temperature from 1000 to 1200°C. The effects of the amount of glass added and the mixing method on the density and the dielectric properties will be discussed