Patent ID: 9236077
Filing Date: 2016-01-12
CPC Classification: C03C,G11B,Y10T

Claim Text:
1. Glass for use in substrate for information recording medium, which comprises SiO 2 ; Al 2 O 3 ; one or more alkali metal oxides selected from the group consisting of Li 2 O, Na 2 O and K 2 O; one or more alkaline earth metal oxides selected from the group consisting of MgO, CaO, SrO and BaO; and one or more oxides selected from the group consisting of ZrO 2 , HfO 2 , Nb 2 O 5 , Ta 2 O 5 , La 2 O 3 , Y 2 O 3 and TiO 2 ; wherein SiO both Li Li Na the total content of the alkali metal oxides and the alkaline earth metal oxides is equal to or greater than 10 molar percent; the molar ratio of the total content of ZrO MgO content is less than 3 molar percent, CaO content is equal to or less than 4 molar percent, and the molar ratio of MgO content to CaO content (MgO/CaO) ranges from 0.227 to 0.727; and the molar ratio of ZrO