EFFECTS OF ALUMINA ON DEVITRIFICATION KINETICS AND MECHANISM OF K2O-CaO-SrO-BaO-B2O3-SiO2 GLASS

• Published in: Jpn.J.Appl.Phys ,Part 1. Vol. 42, no. 7A, pp. 4438-4443. 2003 Vol. 42; no. 7A; pp. 4438 - 4443
• Main Authors: Jean, J-H, Fang, Y-C, Dai, S X, Wilcox, D L
• Format: Journal Article
• Language: English
• Published: 2003
• ISSN: 0021-4922
• DOI: 10.1143/jjap.42.4438

Effects of Al2O3 on the devitrification kinetics and mechanism of a low-dielectric K2O-CaO-SrO-BaO-B2O3-SiO2 glass powder have been investigated. Crystalline phases including cristobalite (SiO2) and pseudowollastonite [(Ca, Ba, Sr)SiO3] are formed during the firing of the pure glass. With added Al2O3 content greater than a critical value, e.g., 10-20 vol% at 900-1000 C, the above crystalline phases are completely prevented but anorthite [(Ca, Sr, Ba)Al2Si2O8] is formed. This result is attributed to the dissolution of Al2O3 into the glass. The dissolution changes the composition of the glass to become Al-rich, and the dissolution kinetics of Al2O3 into the glass is too rapid compared with the formation of cristobalite and pseudowollastonite. The crystallization kinetics of anorthite follows the analysis of the Avrami equations, and the results show an apparent activation energy close to that of the Al-O bond strength, suggesting a reaction-controlled kinetics. 28 refs.