A glass-ceramic comprising, in weight percent on an oxide basis, of 50 to 70% SiO.sub.2, 0 to 20% Al.sub.2O.sub.3, 12 to 23% MgO, 0 to 4% Li.sub.2O, 0 to 10% Na.sub.2O, 0 to 10% K.sub.2O, 0 to 5% ZrO.sub.2, and 2 to 12% F, wherein the predominant crystalline phase of said glass-ceramic is a trisilicic mica, a tetrasilicic mica, or a mica solid solution between trisilicic and tetrasilicic, and wherein the total of Na.sub.2O+Li.sub.2O is at least 2 wt. %; wherein the glass-ceramic can be ion-exchanged.

A multi-fiber light guide includes: light guiding fibers, each fiber including an elongated glass core; a glass cladding, the cores being surrounded by the cladding to form a rigid and continuous glass element, the cores having a higher refractive index than the cladding such that light can be guided by a total reflection along the cores, which end in two abutting faces of the glass element such that light can be guided along the cores from one abutting face to the other abutting face; and an ion exchange layer at each of the abutting faces, the glass of the cores and the glass of the cladding including alkali ions, which are at least partly exchanged by alkali ions of a higher atomic number within the ion exchange layer at the abutting faces, the exchanged alkali ions within the ion exchange layer imparting a compressive stress at the abutting faces.

A glass structure includes: a glass substrate that includes a thick portion and a thin portion thinner than the thick portion; and a filler that covers a step surface formed by difference in height between the thick portion and the thin portion. A refractive index difference at a wavelength of 555 nm between the glass substrate and the filler is 0.008 or less in an absolute value. A refractive index difference at a wavelength of 507 nm between the glass substrate and the filler is 0.008 or less in an absolute value.

Ion-exchanged alkali aluminosilicate glass articles with a ratio of peak compressive stress value to Young's modulus value of 15 or more. The glass articles may include Al.sub.2O.sub.3 mol %+RO mol %≥17 mol %, where RO mol %=MgO mol %+CaO mol %, and be substantially free of ZnO, SrO, BaO, B.sub.2O.sub.3, P.sub.2O.sub.5, Li.sub.2O, and K.sub.2O. The glass articles may have a peak compressive stress value in a range of 500 MPa to 1300 MPa. The glass articles are suitable for various high-strength applications, including cover glass applications that experience significant bending stresses during use, for example, cover glasses for flexible displays.

Glass-based articles comprise stress profiles providing improved fracture resistance. The stress profiles contain a high peak tension and a region with a high degree of negative curvature. The glass-based articles herein provide high fracture resistance after multiple drops.

Crystallized glass and strengthened crystallized glass with a novel composition, which have a high refractive index and high hardness, are provided. A crystallized glass, including, by mass % in terms of oxide, 20.0% or more and less than 40.0% of a SiO.sub.2 component, more than 0% and 20.0% or less of a Rn.sub.2O component, where Rn is one or more selected from Li, Na, and K, 7.0% to 25.0% of an Al.sub.2O.sub.3 component, 0% to 25.0% of a MgO component, 0% to 45.0% of a ZnO component, and 0% to 20.0% of a Ta.sub.2O.sub.5 component, in which a total amount of the MgO component, the ZnO component, and the Ta.sub.2O.sub.5 component is 10.0% or more.

The present invention relates to a chemically strengthened glass article including: a first surface; a second surface facing the first surface; and an end portion in contact with the first surface and the second surface, in which the first surface has a compressive stress value of 400 MPa to 1000 MPa, in which, when a compressive stress value of an inside of the glass is expressed with a depth from the first surface as a variable, a depth m [μm] at which the compressive stress value is maximum is larger than 0 μm, and a value of CS.sub.m−CS.sub.0 [MPa] is 30 MPa or more, and in which a depth DOL at which the compressive stress value is 0 is 50 μm to 150 μm.

The present invention relates to a chemically strengthened glass having a thickness of t [mm], and having a profile of a stress value CS.sub.x [MPa,] at a depth x [.Math.m] from a surface of the glass, the stress value being measured by a scattered-light photoelastic stress meter, in which a second-order differential value CS.sub.x" of the stress value CS.sub.x in the profile satisfies the following expression within a range of CS.sub.x≥0: 0<CS.sub.x"≤0.050.

Glass-based substrates are described herein that may be processed by methods including applying a cover article onto a glass-based substrate, submerging the glass-based substrate in an etchant, and maintaining the submersion of the glass-based substrate in the etchant. The glass-based substrate may include a covered surface portion and an exposed surface portion. At least a portion of the covered surface portion may be in direct contact with the cover article. The covered surface portion may not be in contact with the etchant and the exposed surface portion may be in direct contact with the etchant. The etchant may contact the exposed surface portion and the cover article fora time sufficient to etch the exposed surface portion. The cover article may provide a barrier between the etchant and the covered surface portion for the entirety of the submerging.

Optically transparent glass ceramic materials comprising a glass phase containing and a crystalline tungsten bronze phase comprising nanoparticles and having the formula M.sub.xWO.sub.3, where M includes at least one H, Li, Na, K, Rb, Cs, Ca, Sr, Ba, Zn, Cu, Ag, Sn, Cd, In, Tl, Pb, Bi, Th, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, and U, and where 0<x<1. Aluminosilicate and zinc-bismuth-borate glasses comprising at least one of Sm.sub.2O.sub.3, Pr.sub.2O.sub.3, and Er.sub.2O.sub.3 are also provided.