摘要 |
ACCORDING TO ONE ASPECT OF THE PRESENT INVENTION, PROVIDED IS GLASS FOR USE IN SUBSTRATE FOR INFORMATION RECORDING MEDIUM, WHICH COMPRISES, DENOTED AS MOLAR PERCENTAGES, A TOTAL OF 70 TO 85 PERCENT OF SIO2 AND AL2O3, WHERE SIO2 CONTENT IS EQUAL TO OR GREATER THAN 50 PERCENT AND AL2O3 CONTENT IS EQUAL TO OR GREATER THAN 3 PERCENT; A TOTAL OF EQUAL TO OR GREATER THAN 10 (PERCENT OF LI2O, NA2O AND K2O; A TOTAL OF 1 TO 6 PERCENT OF CAO AND MGO, WHERE CAO CONTENT IS GREATER THAN MGO CONTENT; A TOTAL OF GREATER THAN 0 PERCENT BUT EQUAL TO OR LOWER THAN 4 PERCENT OF ZRO2, HFO2, NB2O5, TA2O5, LA2O3 Y2O3 AND TIO2; WITH THE MOLAR RATIO OF THE TOTAL CONTENT OF LI2O, NA2O AND K2O TO THE TOTAL CONTENT OF SIO2, AL2O3, ZRO2, HFO2, NB2O5, TA2O5, LA2O3, Y2O3 AND TIO2 ((LI2O + NA2O + K2O)/(SIO2 + AL2O3 + ZRO2 + HFO2 + NB2O5 + TA2O5 + LA2O3 + Y2O3 + TIO2)) BEING EQUAL TO OR LESS THAN 0.28. FURTHER PROVIDED ARE THE SUBSTRATE FOR INFORMATION RECORDING MEDIUM, INFORMATION RECORDING MEDIUM AND THEIR MANUFACTURING METHODS ACCORDING TO THE PRESENT INVENTION. |