GLASS FOR COVERING OPTICAL ELEMENT AND LIGHT-EMITTING DEVICE COVERED WITH GLASS

摘要

Disclosed is a glass for covering an optical element, which can seal an optical element at a temperature around 500°C. Also disclosed is a glass-covered light-emitting device which is covered with the glass. The glass essentially comprises 35 to 55% of TeO₂, 20 to 50% of B₂O₃, 10 to 30% of ZnO and 0.1 to 5% of any one member selected from the group consisting of Y₂O₃, La₂O₃, Gd₂O₃ and Bi₂O₃ or a combination of two or more of them, has a (B₂O₃+ZnO)/TeO₂ ratio of 0.9 or more, contains substantially no fluorine, and has a TeO₂ content of 46% or less when the ZnO content is 15% or less, wherein each percentage is expressed on a molar basis in terms of oxide content.