Patent ID: 7964523

Claim:
A glass composition substantially free of alkali metals comprising, calculated as oxides, SiO 2 10-30% by mass, B 2 O 3 20-30% by mass, CaO more than 20% to 40% by mass, MgO 15-40% by mass, BaO + SrO + ZnO 0-10% by mass, La 2 O 3 0-5% by mass, Al 2 O 3 0-5% by mass, and RO 2 0-3% by mass (wherein R represents Zr, Ti, or Sn), wherein a crystallized glass which is formed by firing at 900±50° C. a powder that is made of the glass composition, has a coefficient of thermal expansion of 90-120×10 −7 /° C. at 50-550° C.