A silica-titania glass substrate comprising: (i) a composition comprising 5 weight percent to 10 weight percent TiO.sub.2; (ii) a coefficient of thermal expansion (CTE) at 20° C. in a range from −45 ppb/K to +20 ppb/K; (iii) a crossover temperature (Tzc) in a range from 10° C. to 50° C.; (iv) a slope of CTE at 20° C. in a range from 1.20 ppb/K.sup.2 to 1.75 ppb/K.sup.2; (v) a refractive index variation of less than 140 ppm; and (vi) 600 ppm OH group concentration or greater. The substrate can have a mass of 1 kg or greater and less than 0.05 gas inclusions per cubic inch via a method comprising (i) forming the substrate from soot particles comprising SiO.sub.2 and TiO.sub.2, and (ii) subjecting the substrate to an environment having an elevated temperature and an elevated pressure for a period of time until the substrate comprises less than 0.05 gas inclusions per cubic inch.

A glass has a transmission throughout a wavelength range of from 207 nm to 222 nm of at least 60%, measured at a thickness of 1 mm. The glass is a borosilicate glass having a total platinum content of not more than 3.5 ppm, and a hydrolytic resistance characterized by an extracted Na.sub.2O equivalent in μg per g glass determined according to ISO 719 of not more than 250 μg/g.

Provided is a silica glass member for hermetic sealing of an ultraviolet SMD LED element to be suitably used for hermetic sealing of, and as a transmission window material for, a surface mount-type package (SMD) having an ultraviolet LED mounted thereon and configured to emit ultraviolet light in a wavelength range of from 200 nm to 350 nm. The silica glass member for hermetic sealing includes a silica glass substrate, which is homogeneously and integrally formed without an internal boundary, wherein the silica glass substrate has: a first surface on an inside opposed to an SMD LED element; and a second surface on an outside corresponding to the first surface, wherein an outer peripheral portion of the first surface has formed therein a substrate joining plain surface for joining to the container outer periphery joining plain surface, and wherein the second surface on the outside corresponding to the first surface has formed therein a lens-like convex portion configured to process emitted light from the ultraviolet SMD LED element.

Provided is a glass substrate with which it is possible to reduce dielectric loss in high-frequency signals, and which also has excellent thermal shock resistance. This invention satisfies the relation {Young's modulus (GPa)×average thermal expansion coefficient (ppm/° C.) at 50-350° C.}≤300 (GPa.Math.ppm/° C.), wherein the relative dielectric constant at 20° C. and 35 GHz does not exceed 10, and the dielectric dissipation factor at 20° C. and 35 GHz does not exceed 0.006.

Substantially alkali free glasses are disclosed which can be used to produce substrates for flat panel display devices. The glasses can have a loading of fluorine and ceria to achieve exemplary solarization and UV protection attributes when exposed to UV radiation. Methods for producing substantially alkali free glasses using a float or downdraw process (e.g., a fusion downdraw process) are also disclosed.

Provided is a Li.sub.2O—Al.sub.2O.sub.3—SiO.sub.2-based crystallized glass that has a high permeability to light in an ultraviolet to infrared range and is less susceptible to breakage. A Li.sub.2O—Al.sub.2O.sub.3—SiO.sub.2-based crystallized glass contains, in terms of % by mass, 40 to 90% SiO.sub.2, 1 to 10% Li.sub.2O, 5 to 30% Al.sub.2O.sub.3, 0 to 20% SnO.sub.2, over 0 to 20% ZrO.sub.2, 0 to below 2% TiO.sub.2, 0 to 10% MgO, and 0 to 10% P.sub.2O.sub.5 and includes a β-spodumene solid solution precipitated as a main crystalline phase.

An optical glass includes, in terms of mol % of cations, a total amount of La.sup.3+, Y.sup.3+, and Gd.sup.3+ components falling within a range of from 5% to 65% and a total amount of Zr.sup.4+, Hf.sup.4+, and Ta.sup.5+ components falling within a range of from 5% to 65%, and a relationship expressed in Expression (1) given below is satisfied. (La.sup.3++Y.sup.3++Gd.sup.3+)×(Zr.sup.4++Hf.sup.4++Ta.sup.5+)≥400 (%).sup.2

Glasses containing silicon dioxide (SiO.sub.2) and/or boron oxide (B.sub.2O.sub.3) as glass formers and having a refractive index n.sub.d of greater than or equal to 1.7, as measured at 587.56 nm, and a density of less than or equal to 4.5 g/cm.sup.3, as measured at 25° C., are provided. Optionally, the glasses may be characterized by a low optical dispersion, a high transmittance in the visible and near-ultraviolet (near-UV) range of the electromagnetic spectrum, and/or good glass forming ability.

Glasses containing silicon dioxide (SiO.sub.2) and/or boron oxide (B.sub.2O.sub.3) as glass formers and having a refractive index n.sub.d of greater than or equal to 1.80, as measured at 587.56 nm, a density of less than or equal to 5.5 g/cm.sup.3, as measured at 25° C., and a high transmittance to, particularly to blue light, are provided. Optionally, the glasses may be characterized by a high transmittance in the visible and near-ultraviolet (near-UV) range of the electromagnetic spectrum and/or good glass forming ability.

Glasses containing silicon dioxide (SiO.sub.2) and/or boron oxide (B.sub.2O.sub.3) as glass formers and having a refractive index n.sub.d of greater than or equal to 1.9, as measured at 587.56 nm, and a density of less than or equal to 5.5 g/cm.sup.3, as measured at 25° C., are provided. Optionally, the glasses may be characterized by a high transmittance in the visible and near-ultraviolet (near-UV) range of the electromagnetic spectrum and/or good glass forming ability.