Patent ID: 8288298

Claim:
A glass composition for providing a hermetic seal, the composition comprising, as calculated as oxide, SiO 2 15-30 mass %, Al 2 O 3 0-5 mass %, B 2 O 3 20-35 mass %, CaO 10-25 mass %, MgO 25-40 mass %, ZrO 2 3.5 to 8 mass %, CeO 2 0 to 0.5 mass %, and La 2 O 3 0 to 2 mass %, the composition being substantially free of alkali metals, wherein a crystallized glass which is formed by firing a glass powder made of the glass composition at a temperature of 850-1050Â° C. has a thermal expansion coefficient of 90-110Ã—10 âˆ’7 /Â° C. at 50-550Â° C. and a flexural strength of not less than 80 MPa.