Glasses and glass ceramics including a metal oxide concentration gradient
Embodiments of a glass-based article including a first surface and a second surface opposing the first surface defining a thickness (t) of about 3 millimeters or less (e.g., about 1 millimeter or less), and a stress profile, wherein all points of the stress profile between a thickness range from about 0·t up to 0.3·t and from greater than 0.7·t, comprise a tangent that is less than about −0.1 MPa/micrometers or greater than about 0.1 MPa/micrometers, are disclosed. In some embodiments, the glass-based article includes a non-zero metal oxide concentration that varies along at least a portion of the thickness (e.g., 0·t to about 0.3·t). In some embodiments, the concentration of metal oxide or alkali metal oxide decreases from the first surface to a point between the first surface and the second surface and increases from the point to the second surface. The concentration of the metal oxide may be about 0.05 mol % or greater or about 0.5 mol % or greater throughout the thickness. Methods for forming such glass-based articles are also disclosed.
1. A glass-based article comprising:
a first surface and a second surface opposing the first surface defining a thickness (t); and
a concentration of a metal oxide that is both non-zero and varies along a thickness range from about 0·t to about 0.3·t, as measured by microprobe;
a stress profile, as measured by a combination of scattered light polariscope and surface stress meter, that decreases from the first surface to a value between the first surface and the second surface and increases from the value to the second surface; and
a CT region of the stress profile, wherein the CT region is defined by the equation Stress(x)=MaxCT−(((MaxCT·(n+1))/0.5 n )·|(x/t)−0.5| n ),
wherein MaxCT is a maximum CT value and is provided as a positive value in units of MPa, x is position along the thickenss (t) in micrometers, and n is between 1.5 and 5.
2. The glass-based article of claim 1 , wherein the concentration of the metal oxide is non-zero and varies along the entire thickness.
3. The glass-based article of claim 1 , wherein the metal oxide generates a stress along the thickness range.
4. The glass-based article of claim 1 , wherein the concentration of the metal oxide is about 0.05 mol % or greater throughout the thickness.
5. The glass-based article of claim 1 , wherein the concentration of the metal oxide at the first surface is about 1.5 times greater than the concentration of the metal oxides at a depth equal to about 0.5·t, as measured by microprobe.
6. A glass-based article comprising:
a first surface and a second surface opposing the first surface defining a thickness (t) of about less than about 3 millimeters;
a concentration of a metal oxide that is both non-zero and varies along a thickness range from about 0·t to about 0.3·t as measured by microprobe;
a stress profile, as measured by a combination of scattered light polariscope and surface stress meter, that decreases from the first surface to a value between the first surface and the second surface and increases from the value to the second surface;
a CT region of the stress profile, wherein the CT region is defined by the equation Stress(x)=MaxCT−(((MaxCT·(n+1))/0.5 n )·|(x/t)−0.5| n ),
wherein MaxCT is a maximum CT value and is provided as a positive value in units of MPa, x is position along the thickness (t) in micrometers, and n is between 1.5 and 5; and
wherein all points of the stress profile between a thickness range from about 0·t up to 0.3·t and from greater than 0.7·t, comprise a tangent that is less than about −0.1 MPa/micrometers or greater than about 0.1 MPa/micrometers, and
wherein the stress profile comprises a maximum CS, a DOC and a maximum CT, wherein the ratio of maximum CT to maximum CS is in the range from about 0.01 to about 0.5 and wherein the DOC is about 0.1·t or greater.
7. The glass-based article of claim 6 , further comprising an absolute value of surface CS of about 300 MPa or greater, as measured by surface stress meter.
8. The glass-based article of claim 6 , further comprising an absolute value of surface CS of about 200 MPa or greater, as measured by surface stress meter, and a chemical depth of layer (DOL) of about 0.4·t or greater.
9. The glass-based article of claim 6 , further comprising a CS layer extending from the first surface to a DOC, wherein the DOC is about 0.1·t or greater.
10. The glass-based article of claim 6 , further comprising a CT region, wherein the CT region comprises a metal oxide concentration gradient.
11. The glass-based article of claim 7 , wherein the ratio of maximum CT to surface CS is in the range from about 0.01 to about 0.5.
12. The glass-based article of claim 6 , wherein t comprises about 1 millimeter or less.
13. A glass-based article comprising:
a first surface and a second surface opposing the first surface defining a thickness (t); and
a concentration of a metal oxide that is both non-zero and varies along a thickness range from about 0·t to about 0.3·t, as measured by microprobe;
a stress profile, as measured by a combination of scattered light polariscope and surface stress meter, that decreases from the first surface to a value between the first surface and the second surface and increases from the value to the second surface;
a CT region of the stress profile, wherein the CT region is defined by the equation Stress(x)=MaxCT−(((MaxCT·(n+1))/0.5 n )·|(x/t)−0.5| n ),
wherein MaxCT is a maximum CT value and is provided as a positive value in units of MPa, x is position along the thickness (t) in micrometers, and n is between 1.5 and 5; and
an absolute value of surface CS of about 200 MPa or greater, as measured by surface stress meter.
14. The glass-based article of claim 13 , wherein, when the glass-based article is fractured, the glass-based article fractures into at least 1 fragment/inch 2 up to 40 fragments/inch 2 .
15. The glass-based article of claim 13 , wherein the glass-based article comprises a diffusivity of about 450 μm 2 /hour or greater at about 460 ° C., a maximum CT, and a DOC greater than about 0.15·t, and wherein the surface CS is 1.5 times the maximum CT or greater.
16. The glass-based article of claim 13 , wherein the glass-based article comprises a fracture toughness (K 1C ) of about 0.7 MPa·m 1/2 or greater.
17. The glass-based article of claim 15 , wherein the surface CS is greater than the maximum CT, and wherein the surface CS is about 600 MPa or greater, as measured by surface stress meter.
18. The glass-based article of claim 13 , wherein the concentration of the metal oxide is about 0.05 mol % or greater throughout the thickness.
19. The glass-based article of claim 13 , wherein the concentration of the metal oxide at the first surface is about 1.5 times greater than the concentration of the metal oxide at a depth equal to about 0.5·t, as measured by microprobe.
20. The glass-based article of claim 13 , further comprising an absolute value of surface compressive stress (CS) of about 300 MPa or greater, as measured by surface stress meter.
21. The glass-based article of claim 13 , further comprising a CS layer extending from the first surface to a DOC, wherein the DOC is about 0.1·t or greater.
22. The glass-based article of claim 13 , wherein the CT region comprises a maximum CT and the ratio of maximum CT to surface CS is in the range from about 0.01 to about 0.5.
23. The glass-based article of claim 13 , further exhibiting a transmittance of about 88% or greater over a wavelength in the range from about 380 nm to about 780 nm.
24. The glass-based article of claim 13 , wherein t comprises about 1 millimeter or less.
25. The glass-based article of claim 13 , further comprising a DOC greater than about 0.15·t, and wherein the surface CS is about 300 MPa or greater, as measured by surface stress meter.
26. The glass-based article of claim 13 , wherein the glass-based article comprises a stored tensile energy of about greater than 0 J/m 2 to less than 20 J/m 2 .
27. The glass-based article of claim 13 , further comprising a DOC, wherein 0.25t≧DOC≧0.15 t.
28. A glass-based article comprising:
a first surface and a second surface opposing the first surface defining a thickness (t) of about less than about 3 millimeters;
a concentration of a metal oxide that is both non-zero and varies along a thickness range from about 0·t to about 0.3·t, as measured by microprobe;
a stress profile, as measured by a combination of scattered light polariscope and surface stress meter, that decreases from the first surface to a value between the first surface and the second surface and increases from the value to the second surface;
a CT region of the stress profile, wherein the CT region is defined by the equation Stress(x)=MaxCT−(((MaxCT·(n+1))/0.5 n )·|(x/t)−0.5| n ),
wherein MaxCT is a maximum CT value and is provided as a positive value in units of MPa, x is position along the thickness (t) in micrometers, and n is between 1.5 and 5; and
wherein all points of the stress profile between a thickness range from about 0t up to 0.3t and from greater than 0.7t, comprise a tangent that is less than about −0.1 MPa/micrometers or greater than about 0.1 MPa/micrometers,
wherein the stress profile comprises a maximum CS, a DOC and a maximum CT, wherein the ratio of maximum CT to maximum CS is in the range from about 0.01 to about 0.5 and wherein the DOC is about 0.1·t or greater, and
wherein the glass-based article comprises a stored tensile energy of about greater than 0 J/m 2 to less than 20 J/m 2 .
29. The glass-based article of claim 28 , further comprising an absolute value of surface CS of about 200 MPa or greater, as measured by surface stress meter, and a chemical depth of layer of about 0.4·t or greater.
30. The glass-based article of claim 28 , wherein t comprises about 1 millimeter or less.
31. An electronic device comprising the glass-based article of claim 1 .
32. An electronic device comprising the glass-based article of claim 6 .
33. An electronic device comprising the glass-based article of claim 13 .
34. An electronic device comprising the glass-based article of claim 28 .