| abstract |
A dopant host having high heat resistance and a high volatilization amount of B 2 O 3 is provided. A SiO 2 30 to 60 mol%, Al 2 O 3 10~30 mol%, B 2 O 3 15~50 mol%, RO (R is an alkaline earth metal) containing a composition of 2-15 mol% boron component volatilization layer, and SiO 2 8 to 40 mol%, Al 2 O 3 40~85 mol%, B 2 O 3 5~30 mol%, RO (R is an alkaline earth metal) 0.5 to 7 mol A dopant host comprising a laminate including a heat-resistant layer containing a composition of 2%. [Selection figure] None |