GLASS FOR SUBSTRATE

摘要

Disclosed is a glass for a substrate, which shows a transmittance of light having a wavelength of 5.5 µm of 50% or more and a transmittance of light having a wavelength of 7.0 µm of 10% or less when prepared in a thickness of 1 mm. Specifically disclosed is a glass for a substrate, which comprises (by mole, in terms of oxide): 10 to 55% of Bi<SUB>2</SUB>O<SUB>3</SUB>; 20 to 85% of GeO<SUB>2</SUB>; 0 to 19% of Ga<SUB>2</SUB>O<SUB>3</SUB>; and 0 to 15% of Al<SUB>2</SUB>O<SUB>3</SUB>, wherein the sum total of Bi<SUB>2</SUB>O<SUB>3</SUB> and GeO<SUB>2</SUB> accounts for 50% or more and, when MgO is contained, the sum total of Ga<SUB>2</SUB>O<SUB>3</SUB> and MgO accounts for 20% or less. In the glass, the content of Bi<SUB>2</SUB>O<SUB>3</SUB> may be 15% or more, the content of GeO<SUB>2</SUB> may be 80% or less, and the sum total of Ga<SUB>2</SUB>O<SUB>3</SUB> and Al<SUB>2</SUB>O<SUB>3</SUB> may account for 2 to 30%. In the glass, the sum total of GeO<SUB>2</SUB> and Al<SUB>2</SUB>O<SUB>3</SUB> may account for 60% or more. The glass may have a glass transition temperature of 400°C or higher.