A mask blank glass substrate having a maximum value of a circularly averaged power spectral density of 1,000 nm.sup.4 or less at a spatial frequency of 0.1 m.sup.1 or more and 20 m.sup.1 or less, the maximum value being obtained by measuring a surface morphology of a region of 10 m10 m with an atomic force microscope.

A tube glass of the present invention includes an alkali silicate glass, in which a glass composition is substantially free of B.sub.2O.sub.3 and Al.sub.2O.sub.3, and a loss in mass ? (mg/dm.sup.2) in an alkali resistance test in accordance with ISO 695 (199105-15) is classified as Class A1.

An optical glass comprising: by cation %, more than 0% and up to 40% of a content rate of La.sup.3+; 15% to 65% of a content rate of Ti.sup.4+; and more than 0% and up to 20% of a content rate of Zr.sup.4+; wherein a refractive index (n.sub.d) with respect to a d-line is from 2.00 to 2.35.

Near-infrared shielding includes a glass material. The shielding provides transmittance at wavelengths between 390 to 700 nm, but near infrared absorbing species are distributed throughout the glass material and the shielding blocks light in the near infrared range. Further, the glass material has a near zero or negative coefficient of thermal expansion, allowing the glass material to heat up when the shielding is blocking a near infrared laser, without expanding much.

To provide a a glass composition which can be used for a dental porcelain or a dental ceramics coloring material, and has low temperature meltability, acid resistance and preservation stability under the humid environment which are required for a dental porcelain or a dental ceramics coloring material, and a dental porcelain and dental ceramics coloring material which contain the glass composition of the present disclosure. To provide a low melting glass composition with softening point (Ts) less than 600 C. comprising as a component; SiO.sub.2: 55.0 to 75.0 wt. %, B.sub.2O.sub.3: 6.1 to 12.0 wt. %, Al.sub.2O.sub.3: 2.0 to 8.0 wt. %, ZnO: 2.0 to 8.5 wt. % and two or more kinds of alkali metal oxide: 10.5 to 20.0 wt. %.

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.

A glass composite for use in Extreme Ultra-Violet Lithography (EUVL) is provided. The glass composite includes a first silica-titania glass section. The glass composite further includes a second doped silica-titania glass section mechanically bonded to a surface of the first silica-titania glass section, wherein the second doped silica-titania glass section has a thickness of greater than about 1.0 inch.

The present invention relates to a moldable nanocomposite for producing a transparent article made of multicomponent fused silica glass, the moldable nanocomposite comprising: an organic binder; and a fused silica glass powder dispersed in the organic binder, the fused silica glass powder comprising fused silica glass particles having a diameter in the range from 5 nm to 500 nm, wherein the fused silica glass powder is pre-modified with a dopant and/or wherein at least one non-crystalline modifying agent is contained in the moldable nanocomposite and one or more dopant reagents selected from organoelement compounds, metal complexes and salts are contained in the moldable nanocomposite as the at least one non-crystalline modifying agent, and wherein the content of the fused silica glass powder in the moldable nanocomposite is at least 5 parts per volume based on 100 parts per volume of the organic binder. Further, the present invention relates to a method of producing a transparent article made of multicomponent fused silica glass.

In order to reduce the degree of relaxation after an optical substrate has been compacted, in particular after a longer period, substrates (51) or reflective optical elements (50), in particular for EUV lithography, with substrates (51) of this type, are proposed. These substrates (51), which have a surface region (511) with a reflective coating (54), are characterised in that, at least near to the surface region (511), the titanium-doped quartz glass has a proportion of SiOOSi bonds of at least 1*10.sup.16/cm.sup.3 and/or a proportion of SiSi bonds of at least 1*10.sup.16/cm.sup.3 or, along a notional line (513) perpendicular to the surface region (511), over a length (517) of 500 nm or more, a hydrogen content of more than 5?10.sup.18 molecules/cm.sup.3.

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.