Glass ceramic with reduced lithium content
A transparent colored glass ceramic, in particular an LAS glass ceramic, suitable for use as a cooking surface is provided. The transparent colored glass ceramic includes high-quartz solid solution (HQ s.s.) as a main crystal phase and exhibits thermal expansion of −1 to +1 ppm/K in the range from 20° C. to 700° C. The glass ceramic has from 3.0 to 3.6 percent by weight of lithium oxide (Li 2 O) as constituents and either is colored with 0.003 to 0.05 percent by weight of vanadium oxide (V 2 O 5 ) or is colored with 0.003 to 0.25 percent by weight of molybdenum oxide (MoO 3 ).
1. A transparent colored glass ceramic, comprising:
high-quartz solid solution as a main crystal phase;
a thermal expansion of −1 to +1 ppm/K in a range from 20° C. to 700° C.;
3.0 to 3.6 percent by weight of lithium oxide (Li 2 O); and
a colorant that is 0.003 to 0.25 percent by weight of molybdenum oxide (MoO 3 ).
2. The glass ceramic as claimed in claim 1 , wherein the transparent colored glass ceramic is an LAS glass ceramic.
3. The glass ceramic as claimed in claim 1 , further comprising:
a coloring oxide in an amount from 0 to less than 0.01 percent by weight, the coloring oxide being selected from a group consisting of CoO, NiO, Cr 2 O 3 , CuO, Nd 2 O 3 , and combinations thereof.
4. The glass ceramic as claimed in claim 1 , further comprising, in percent by weight:
BaO
1.2 to 2.8;
MgO
0 to less than 1;
CaO
0 to less than 1; and
ZnO
1.2 to 2.5.
5. The glass ceramic as claimed in claim 1 , further comprising 0.1 to 0.6 percent by weight of tin oxide (SnO 2 ).
6. The glass ceramic as claimed in claim 1 , further comprising, in percent by weight:
SiO 2
62 to 68;
Al 2 O 3
18.5 to 23;
Li 2 O
3.0 to 3.6;
V 2 O 5
0.03 to 0.05
SnO 2
0.1 to 0.6;
BaO
1.2 to 2.8;
MgO
0 to less than 1;
ZnO
1.2 to 2.5;
TiO 2
2.6 to 4.5;
ZrO 2
0.9 to 1.7;
B 2 O 3
0 to 2;
P 2 O 5
0 to 4;
Na 2 O + K 2 O
0 to less than 1.5;
CaO
0 to less than 1;
SrO
0 to less than 1;
Fe 2 O 3
0 to 0.2.
7. The glass ceramic as claimed in claim 6 , wherein the Li 2 O is 3.2 to 3.6 in percent by weight.
8. The glass ceramic as claimed in claim 6 , wherein the MgO is 0.3 to less than 1 in percent by weight.
9. The glass ceramic as claimed in claim 6 , wherein the Na 2 O+K 2 O is 0 to less than 1 in percent by weight.
10. The glass ceramic as claimed in claim 6 , wherein the Fe 2 O 3 is 0 to 0.15 in percent by weight.
11. The glass ceramic as claimed in claim 1 , further comprising a ratio (BaO+ZnO) /MgO in percent by weight in a range from 2.2 to 35.
12. The glass ceramic as claimed in claim 1 , further comprising a compound selected from a group consisting of arsenic (As), antimony (Sb), cadmium (Cd), lead (Pb), halides, sulfur (S) in an amount from 0 to less than 0.5 percent by weight.
13. The glass ceramic as claimed in claim 12 , wherein the amount is less than 0.05 percent by weight.
14. The glass ceramic as claimed in claim 1 , wherein the high-quartz solid solution accounts for more than 80% of existing crystal phases and wherein further crystal phases, only nucleation phases or keatite solid solution (K s.s.), account for an amount of not more than 20% of the crystal phase fraction.
15. The glass ceramic as claimed in claim 1 , further comprising, at a thickness of 4 mm, a light transmittance from 0.5% to 70%.
16. The glass ceramic as claimed in claim 15 , wherein the light transmittance is from 0.5% to 20%.
17. The glass ceramic as claimed in claim 1 , further comprising a viscosity of 200 dPa•s at less than 1750° C.
18. The glass ceramic as claimed in claim 1 , further comprising a thermal expansion, in a range from 20° C. to 700° C., of 0 to 0.41 ppm/K.
19. The glass ceramic as claimed in claim 1 , wherein the glass ceramic is configured for a use selected from a group consisting of a cooking surface, a fireplace window, a grill surface, a roasting surface, a cover of a fuel element in a gas grill, an oven door, a pyrolysis oven door, a kitchen or laboratory surface, a cover for a lighting device, a fire-resistant glazing, a safety glass, a laminate composite, a support plate or furnace lining of a thermal processes, and a back cover for mobile electronic device.
20. The glass ceramic as claimed in claim 3 , further comprising MnO 2 in an amount from 0 to less than 0.3 percent by weight.
21. The glass ceramic as claimed in claim 1 , wherein the colorant further comprises 0.003 to 0.05 percent by weight of vanadium oxide (V 2 O 5 ).
22. The glass ceramic as claimed in claim 1 , further comprising a transmission of equal to or more than 45% to equal to or less than 85% at a wavelength of 1600 nm.
23. A transparent colored glass ceramic, comprising:
high-quartz solid solution as a main crystal phase;
a thermal expansion of −1 to +1 ppm/K in a range from 20° C. to 700° C.;
3.0 to 3.6 percent by weight of lithium oxide (Li 2 O);
a colorant comprising molybdenum oxide (MoO 3 ); and
a transmission of equal to or more than 45% and equal to or less than 85% at a wavelength of 1600 nm.
24. The glass ceramic of claim 23 , wherein the colorant further comprises vanadium oxide (V 2 O 5 ).
25. The glass ceramic of claim 23 , wherein the colorant is 0.003 to 0.25 percent by weight of molybdenum oxide (MoO 3 ).
26. The glass ceramic of claim 24 , wherein the weight of vanadium oxide (V 2 O 5 ) comprises 0.003 to 0.05 percent by weight of vanadium oxide (V 2 O 5 ).