Information recording medium glass substrate and information recording medium

• Main Author: TSUDA KOUICHI,KOBAYASHI RYOJI
• Format: Patent
• Language: English
• Published: 21.11.2007
• Subjects: CHEMICAL COMPOSITION OF GLASSES, GLAZES, OR VITREOUSENAMELS; CHEMISTRY; GLASS; INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; JOINING GLASS TO GLASS OR OTHER MATERIALS; METALLURGY; MINERAL OR SLAG WOOL; PHYSICS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS,MINERALS OR SLAGS; SURFACE TREATMENT OF GLASS

Information recording medium glass substrate which is a molded article composed of an alkali metal-containing glass material having a composition including at least B, Al, alkali metals, Zn, and Si, and satisfying certain relational equations in molar proportions in terms of oxides thereof, has a low molding temperature, excellent durability, and a reduced number of surface defects. An information recording medium having such a glass substrate and a magnetic layer formed thereon has excellent low-temperature workability and excellent weathering resistance. The glass substrate is suitable for perpendicular magnetic recording because the glass composition suppresses alkali elution from the glass substrate and the glass substrate has substantially no surface-attached foreign matter having a height of about 10 nm or less and having SiO2 as a main component thereof.