Glass substrate for information recording media and information recording medium
Provided are a glass substrate for information recording media wherein air bubbles can be sufficiently removed, and an information recording medium using the glass substrate. The glass substrate contains 65 to 90 mass % of SiO 2 +Al2O 3 +B 2 O 3 (where SiO 2 is 45 to 75 mass %, Al 2 O 3 is 1 to 20 mass %, and B 2 O 3 is 0 to 8 mass %), 7 to 20 mass % of R2O (where R represents Li, Na, or K), 0.1 to 12 mass % of R′O (where R′ represents Mg, Ca, Sr, Ba, or Zn), and 0.5 to 10 mass % of TiO 2 +ZrO 2 . Moreover, the glass substrate contains at least one multivalent element selected from among a group consisting of V, Mn, Ni, Mo, Sn, Ce, and Bi; the molar ratio of the total amount of the oxide of the multivalent element to the total amount of TiO 2 +ZrO 2 is within the range of 0.05 to 0.50.
1. A glass substrate for information recording media, comprising, with respect to all components of the glass substrate:
45% to 75% by mass of SiO 2 ;
1% to 20% by mass of Al 2 O 3 ; and
0% to 8% by mass of B 2 O 3 ,
wherein a total amount of the SiO 2 , the Al 2 O 3 , and the B 2 O 3 is 65% to 90% by mass;
R 2 O, a total amount of which being 7% to 20% by mass
where:
R represents Li, Na, or K;
R′O, a total amount of which being 0.1% to 12% by mass
where:
R′ represents Mg, Ca, Sr, Ba, and Zn;
TiO 2 ; and optionally ZrO 2 , where TiO 2 is an essential component, and a total amount of TiO 2 and the optional ZrO 2 is 0.5% to 10% by mass and the amount of TiO 2 is 2.5% by mass or less,
wherein the glass substrate for information recording media comprises at least one polyvalent element selected from a group consisting of V, Mn, Ni, Mo, Sn, Ce, and Bi, and
wherein a mole ratio, which is (a total amount of an oxide of the polyvalent element)/(a total amount of the TiO 2 and the ZrO 2 ), of the total amount of the oxide of the polyvalent element with respect to the total amount of the TiO 2 and the ZrO 2 is in a range of 0.10 to 0.50, assuming each of oxides of polyvalent elements as V 2 O 5 , MnO 2 , Ni 2 O 3 , MoO 3 , SnO 2 , CeO 2 , and Bi 2 O 3 .
2. The glass substrate for information recording media of claim 1 , wherein:
0% to 5% by mass of Ln x O y , the Ln x O y being at least one compound selected from a group consisting of a lanthanoid metal oxide, Y 2 O 3 , Nb 2 O 5 , and Ta 2 O 5 .
3. The glass substrate for information recording media of claim 1 , wherein the polyvalent element includes at least one element selected from a group consisting of V, Mn, Sn, and Ce.
4. The glass substrate for information recording media of claim 3 , wherein the polyvalent element includes Ce.
5. The glass substrate for information recording media of claim 1 , wherein a content of each of the oxides of the polyvalent elements V 2 O 5 , MnO 2 , Ni 2 O 3 , MoO 3 , SnO 2 , CeO 2 , and Bi 2 O 3 is 1% by mass or less with respect to the all components of the glass substrate.
6. The glass substrate for information recording media of claim 1 , wherein the components of the glass substrate includes neither As nor Sb.
7. The glass substrate for information recording media of claim 1 , wherein the total amount of TiO 2 and the optional ZrO 2 is 1.3% to 10% by mass.
8. The glass substrate for information recording media of claim 1 comprising:
ZrO 2 , wherein the total amount of TiO 2 and ZrO 2 is 0.5% to 10% by mass.
9. The glass substrate for information recording media of claim 1 wherein the mole ratio of the total amount of the oxide of the polyvalent element to the total amount of the TiO 2 and the ZrO 2 controls the number of residual gas bubbles in the glass substrate.
10. An information recording medium, comprising:
a glass substrate the glass substrate comprising
45% to 75% by mass of SiO 2 ;
1% to 20% by mass of Al 2 O 3 ; and
0% to 8% by mass of B 2 O 3 ,
wherein a total amount of the SiO 2 , the Al 2 O 3 , and the B 2 O 3 is 65% to 90% by mass;
R 2 O, a total amount of which being 7% to 20% by mass
where:
R represents Li, Na, or K;
R′O, a total amount of which being 0.1% to 12% by mass
where:
R′ represents Mg, Ca, Sr, Ba, and Zn;
TiO 2 ; and optionally ZrO 2 , where TiO 2 is an essential component, and a total amount of TiO 2 and the optional ZrO 2 is 0.5% to 10% by mass and the amount of TiO 2 is 2.5% by mass or less,
wherein the glass substrate comprises at least one polyvalent element selected from a group consisting of V, Mn, Ni, Mo, Sn, Ce, and Bi, and
wherein a mole ratio, which is (a total amount of an oxide of the polyvalent element)/(a total amount of the TiO 2 and the ZrO 2 ), of the total amount of the oxide of the polyvalent element with respect to the total amount of the TiO 2 and the ZrO 2 is in a range of 0.10 to 0.50, assuming each of oxides of polyvalent elements as V 2 O 5 , MnO 2 , Ni 2 O 3 , MoO 3 , SnO 2 , CeO 2 , and Bi 2 O 3 ; and
a recording layer provided on a surface of the glass substrate.