GLASS OR GLASS-CERAMIC

摘要

The invention discloses a glass and a glass-ceramic which at least include the constituents SiO2, Al2O3 and Y2O3 and is pref- erably doped with rare earth ions. The weight ratio between the weight of Y2O3 and the total weight of SiO2, Al2O3 and Y2O3 is at least 0.2, preferably at least 0.4 or more. The rare earth ions can preferably be incorporated in crystal phases with a high yttrium content which are precipitated from the glass.