Dielectric, thermal and sintering behavior of BaO-B2O3-SiO2 glasses with the addition of Al2O3

In the Pb-free low temperature sinterable glass of the (55)BaO-(35)B₂O₃-(10)SiO₂ system, different amounts of Al₂O₃ were added and the crystallization behavior, sintering behavior and physical characteristics of the glass were examined. It was found that Al₂O₃ suppressed crystallization of the glasses because it played the role of a network former. The glass transition temperatures, crystallization temperatures, and optimum sintering temperatures increased as the amount of Al₂O₃ increased. In the case of a specimen with a large amount of Al₂O₃, which was not easily crystallized, an over-firing phenomenon was observed when the sintering temperature was higher than the optimum sintering temperature. While the over-firing phenomenon was not observed due to the crystallization in the sample with a little amount of Al₂O₃. The dielectric constant and thermal expansion coefficient of the glasses were also examined and explained in correlation with the crystallization and densification.