Microwave dielectric properties of ceramic/glass composites with bismuth-zinc borosilicate glass

摘要

The microwave dielectric properties of ceramic/bismuth zinc borosilicate (BZBS) glass composites were investigated. The crystalline phases of ZnAl2O4 with a spinel structure in the Al2O3/BZBS glass composite and Bi2Ti2O7 with a cubic pyrochlore structure in the TiO2/BZBS glass composite were observed, indicating that BZBS glass was a reactive glass in these systems. A one-stage sintering occurred in the Al2O3/BZBS glass composite whereas a two-stage one might occur in the TiO2/BZBS glass composite. The dielectric constant (ε_r) of the Al2O3/BZBS glass composite exhibited almost the same value of about 10 within the sintering temperature range between 600-950 °C, implying that the application of the Al2O3/BZBS glass composite to substrates may therefore be shown to be appropriate. For the TiO2/BZBS glass composite, however, an improvement of the temperature coefficient of the resonant frequency (τ_f=+119ppm/K) is necessary for the application as LTCC materials although the dielectric constant of this system had a proper value (～56) for an application to filters.