Provided is an optical fiber containing an alkali metal element or the like having a smaller diffusion coefficient than K and having a low Rayleigh scattering loss. An optical fiber is composed of silica glass and includes a core and a cladding arranged to surround the core which has a lower refractive index than the core. The core includes a first core including a central axis and a second core arranged to surround the first core. The average concentration of an alkali metal element or alkaline-earth metal element in the first core is 10 mol ppm or less. The average concentration of chlorine in the first core is 2000 mol ppm or more. The average concentration of an alkali metal element or alkaline-earth metal element in the second core is 10 mol ppm or more. The average concentration of chlorine in the second core is 10 to 600 mol ppm.

A glass is described, a glass article made of the glass as well as uses and production methods. The glass constituents are selected such that it results in excellent chemical stability and ion ex-changeability. The glass has a composition characterized by the following glass constituent phases: 0-35 mol % reedmergnerite; 10-60 mol % albite; 3.5-25 mol % orthoclase; 0-40 mol % natrosilite; 0-20 mol % parakeldyshite; 0-20 mol % narsarsukite; 0-35 mol % disodium zinc silicate; 0-35 mol % silicon dioxide; 0-30 mol % cordierite; and 0-20 mol % danburite. A quotient of a coefficient of thermal expansion of the glass multiplied by 1000 (in ppm/K) and the product of a pH value and a removal rate in alkaline environment (in mg/(dm.sup.23h)) according to ISO 695 is at least 9.25.

Glass-based articles are manufactured by a unique ion exchange process that results in glass-based articles having improved stress profiles with higher stress values at moderate depths. A medium of the ion exchange process includes ions of two or more alkali metals of two or more alkali metal oxides in a base composition of a glass-based substrate in a ratio such that ions of each alkali metal are in chemical equilibrium with each of the respective alkali metals of the alkali metal oxides in the base glass composition.

The disclosure relates to highly temperable colored glass compositions. The colored glass compositions have high coefficients of thermal expansion and high Young's moduli that advantageously absorb in the ultraviolet and/or blue wavelength ranges. Methods of making such glasses are also provided.

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.

Provided is a glass composition comprising a glass frit containing P.sub.2O.sub.5, BaO, ZnO, group I-based oxide and group II-based oxide, wherein the P.sub.2O.sub.5 is contained in an amount of 20 wt % to 55 wt % based on a total weight of the glass frit, wherein each of the BaO and ZnO is contained in an amount of 2 to 30% by weight based on the total weight of the glass frit, wherein the group I-based oxide is contained in an amount of 5 to 20% by weight based on the total weight of the glass frit, wherein the group II-based oxide is contained in an amount of 1 to 15% by weight based on the total weight of the glass frit.

Disclosed in the present application is a lithium-aluminosilicate glass. The lithium-aluminosilicate glass includes, by mole percent of oxides, the following components: SiO.sub.2, 62-68 mol %; Al.sub.2O.sub.3, 9-14 mol %; Na.sub.2O, 6-10 mol %; K.sub.2O, 0.2-0.7 mol %; and Li.sub.2O, 8.0-14.0 mol %; where (Li.sub.2O+Na.sub.2O+MgO)/Al.sub.2O.sub.3 is 1.7-2.5. By means of controlling the mole percents of SiO.sub.2, Al.sub.2O.sub.3, Na.sub.2O, K.sub.2O, and Li.sub.2O, as well as the range of the ratio (Li.sub.2O+Na.sub.2O+MgO)/Al.sub.2O.sub.3, it is consequently ensured that the obtained lithium-aluminosilicate glass, upon chemical strengthening, has high strength, satisfies a requirement of a client with respect to film-peeling electrostatic voltage, and further has uniquely advantageous effects of a lower melting temperature and being able to save energy and reduce energy consumption.

An alkali-free glass of the present invention includes as a glass composition, in terms of mass %, 55% to 70% of SiO.sub.2, 15% to 25% of Al.sub.2O.sub.3, 0% to 1% of B.sub.2O.sub.3, 0% to 0.5% of Li.sub.2O+Na.sub.2O+K.sub.2O, 2% to 6% of MgO, 2% to 8% of CaO, 0% to 4% of SrO, and 6% to 12% of BaO, and has a strain point of more than 720 C.

The optical fiber offered is capable of not only restraining the attenuation due to glass defects, but also reducing the increase of manufacturing cost. The optical fiber is made of silica glass and includes a core and a cladding. The cladding encloses the core and has a refractive index smaller than that of the core. When the core is divided into inner core and outer core at half of the radius of the core, the average chlorine concentration of the inner core is larger than that of the outer core. The core includes any of the alkali metal group.

A glass composition includes: 50 mol % to 69 mol % SiO.sub.2; 12.5 mol % to 25 mol % Al.sub.2O.sub.3; 0 mol % to 8 mol % B.sub.2O.sub.3; greater than 0 mol % to 4 mol % CaO; greater than 0 mol % to 17.5 mol % MgO; 0.5 mol % to 8 mol % Na.sub.2O; 0 mol % to 2.5 mol % La.sub.2O.sub.3; and greater than 8 mol % to 18 mol % Li.sub.2O, wherein (Li.sub.2O+Na.sub.2O+MgO)/Al.sub.2O.sub.3 is from 0.9 to less than 1.3; and Al.sub.2O.sub.3+MgO+Li.sub.2O+ZrO.sub.2+La.sub.2O.sub.3+Y.sub.2O.sub.3 is from greater than 23 mol % to less than 50 mol %. The glass composition may be characterized by at least one of the following: a K.sub.1C value measured by a chevron short bar method of at least 0.75; and a K.sub.1C value measured by a double torsion method of at least 0.8. The glass composition is chemically strengthenable. The glass composition may be used in a glass article or a consumer electronic product.