Evaluation of Properties of High Transparency Li2B4O7-BaO-P2O5-Al2O3 Sealing Glass

We prepared and evaluated the heat characteristics, thermal expansion, water durability, transparency, and sealing strength of glasses comprising 30-80 mol% Li2B4O7, 10-40 mol% BaO, and 10-40 mol% P2O5. Addition of Al2O3 to the Li2B4O7-BaO-P2O5 glasses was found to improve their transparency. In particular, glass comprising 53.0 mol% Li2B4O7, 15.2 mol% BaO, 7.6 mol% P2O5, 24.2 mol% Al2O3 (LiBaP + 24.2Al) had high transparency, high water durability, and a low thermal expansion coefficient equal to that of soda lime glass without the addition of a low thermal expansion ceramic filler. Furthermore, the LiBaP + 24.2Al glass had high sealing ability (6.64 kgf/cm(2)) compared to lead glass (1.63 kgf/cm(2)).