Anisotropic glass
View Patent ↗The present invention relates to an anisotropic glass containing, in terms of mol % on the basis of oxides, P 2 O 5 in a content of from 45 mol % to 57 mol %, two or more kinds of alkali metal oxides selected from the group consisting of Li 2 O, Na 2 O, K 2 O, Rb 2 O, and Cs 2 O in a total content of from 30 mol % to 54 mol %, and at least one polyvalent element oxide other than P 2 O 5 in a total content of from 0.1 mol % to 20 mol %, and having a birefringence of 30×10 −6 or more.
1. An anisotropic glass
comprising, in terms of mol % on the basis of oxides,
P 2 O 5 in a content of from 45 mol % to 57 mol %,
three or more alkali metal oxides selected from the group consisting of Li 2 O, Na 2 O, K 2 O, Rb 2 O, and Cs 2 O in a total content of from 30 mol % to 54 mol %, and
at least one polyvalent element oxide other than P 2 O 5 in a total content of from 0.1 mol % to 20 mol %, and
having a birefringence of 30×10 −6 or more.
2. The anisotropic glass according to claim 1 , comprising four or more alkali metal oxides selected from the group consisting of Li 2 O, Na 2 O, K 2 O, Rb 2 O, and Cs 2 O.
3. The anisotropic glass according to claim 1 , wherein the content of an alkali metal oxide having the largest content in the three or more alkali metal oxides selected from the group consisting of Li 2 O, Na 2 O, K 2 O, Rb 2 O, and Cs 2 O is taken as x 1 and the content of an alkali metal oxide having the smallest content is taken as x 2 and a molar ratio x 1 /x 2 of the contents is 2 or less.
4. The anisotropic glass according to claim 2 , comprising Na 2 O, K 2 O and Cs 2 O.
5. The anisotropic glass according to claim 1 , comprising, as the polyvalent element oxide other than P 2 O 5 , at least one selected from the group consisting of MgO, CaO, SrO, BaO, ZnO, B 2 O 3 , Al 2 O 3 , Fe 2 O 3 , and SiO 2 .
6. The anisotropic glass according to claim 5 , comprising Al 2 O 3 in a content of from 0.1 mol % to 10 mol %.
7. The anisotropic glass according to claim 3 , wherein the molar ratio x 1 /x 2 is 1.5 or less.
8. The anisotropic glass according to claim 1 , comprising, as the polyvalent element oxide other than P 2 O 5 , at least two selected from the group consisting of MgO, CaO, SrO, BaO, ZnO, B 2 O 3 , Al 2 O 3 , Fe 2 O 3 , and SiO 2 .
9. The anisotropic glass according to claim 1 , wherein the three or more alkali metal oxides are Cs 2 O, K 2 O, and Na 2 O.
10. The anisotropic glass according to claim 1 , wherein the content of P 2 O 5 is 48 mol % to 55 mol %.
11. The anisotropic glass according to claim 1 , wherein the content of P 2 O 5 is 49 mol % to 52 mol %.
12. The anisotropic glass according to claim 1 , wherein the total content of the three or more alkali metal oxides is 35 mol % to 50 mol %.
13. The anisotropic glass according to claim 1 , wherein the total content of the three or more alkali metal oxides is 40 mol % to 49 mol %.
14. The anisotropic glass according to claim 1 , wherein the total content of the polyvalent element oxide other than P 2 O 5 is 1% to 10%.
15. The anisotropic glass according to claim 1 , wherein the polyvalent element oxide other than P 2 O 5 is BaO.
16. The anisotropic glass according to claim 1 , wherein the content Al 2 O 3 is 1 mol % to 5 mol %.