Abstract:
Ultraviolet (UV) radiation in the UV-C and UV-B bands, which is particularly dangerous, is absorbed and filtered by quartz glass doped with between 0.065% and 3.25%, and preferably between 0.065% and 1.3%, by weight, of cerium metal, or cerium as such. Preferably, the cerium is added to quartz sand and/or rock crystal, in form of a fine-grained powder of up to 20 .mu.m grain size, in form of cerium aluminate (CeAlO.sub.3), present in up to about 5% by weight, and preferably up to about 2%, by weight, and melted together in a single step. The quartz glass so obtained is particularly suitable for a metal halide discharge lamp, e.g. as an outer envelope (1), or as the discharge vessel (27) itself, or for halogen incandescent lamps, to form the quartz-glass light bulb or an envelope therefor. A small quantity of titanium oxide, up to about 0.05%, may be added as a further doping agent to the melt to further improve the UV absorption in the B and C bands.
Abstract:
Gradient-index glass is produced in a sol-gel process by utilizing water or a mixture of water and alcohol. This technique is particularly suitable for production of glass bodies with a ternary system of metal alkoxides, including silicon alkoxide, an index modifying metal alkoxide, such as alkoxides of titanium and zirconium, and an additional metal alkoxide, such as an alkoxide of aluminum, boron, or germanium.
Abstract:
In producing silica glass, which may contain additional metal(s) such as Ti or Zr, from a solution of a silicon alkoxide, mixed with alkoxide(s) of the additional metal(s) where necessary, in water and a hydrophilic organic solvent by shaping the solution into a desired form such as a coating film on a substrate, self-supporting film, fiber or lump when the solution exhibits a suitably high viscosity and sufficiently heating the shaped solution, a water-soluble organic polymeric substance is added to the solution as a viscosity adjusting agent to soon increase the viscosity of the solution to the desirable level. Therefore, shaping of the solution can be performed without awaiting the progress of hydrolysis of the alkoxide in the solution, and the glass can be obtained with improved uniformity of its properties. A cellulose ether is preferred as the viscosity adjusting agent, and hydroxypropyl cellulose is particularly preferable.
Abstract:
This invention relates to the immobilization of toxic, e.g., radioactive materials, internally in a silicate glass or silica gel matrix for extremely long periods of time. Toxic materials, such as radioactive wastes containing radioactive anions, and in some cases cations, which may be in the form of liquids, or solids dissolved or dispersed in liquids or gases, are internally incorporated into a glass matrix, having hydrous organofunctionalsiloxy groups, e.g., hydrous aminoalkylsiloxy or carboxyorganosiloxy, bonded to silicon atoms of said glass and/or hydrous polyvalent metals bonded to silicon atoms of said glass through divalent oxygen linkages or otherwise immobilized therein, by a process which involves the ion exchange of said toxic, radioactive anions with hydroxyl groups attached to said organofunctionalsiloxy groups or with hydroxyl groups attached to the hydrous polyvalent metal. Thereafter, the resulting glass now characterized by a distribution of internally bonded or immobilized, toxic, radioactive anions can be packaged in suitable containers, and disposed of as by burial, and/or they can be sintered to collapse the pores thereof prior to disposal or for producing useful radiation sources. The porous glass or a porous silica gel having said silicon-bonded organofunctionalsiloxy groups and/or said hydrous polyvalent metal oxy groups, the pores of said glass or silica gel remaining open and uncollapsed, can be used advantageously as a backfill for an underground radioactive waste burial site and as overpack in the waste disposal container. Also included is a novel method for bonding the polyvalent metal to the porous silica glass or gel by substituting the protons of the silicon-bonded hydroxyl groups thereof with an alkali metal or ammonium cation followed by displacement of said cation with the non-radioactive polyvalent metal cation.
Abstract:
A method is disclosed wherein high purity fused silica is produced from a liquid flowable form of a silica slurry or sol and the refractoriness of the fused silica is enhanced by homogeneously doping the silica with aluminum and/or titanium oxide, preferably in conjunction with elemental silicon.
Abstract:
Glasses containing silicon dioxide (SiO2) and/or boron oxide (B2O3) as glass formers and having a refractive index nd 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/cm3, 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.
Abstract:
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.
Abstract:
Glasses containing silicon dioxide (SiO2) and/or boron oxide (B2O3) as glass formers and having a refractive index nd 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/cm3, 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.
Abstract:
A method of forming a doped silica-titania glass is provided. The method includes blending batch materials comprising silica, titania, and at least one dopant. The method also includes heating the batch materials to form a glass melt. The method further includes consolidating the glass melt to form a glass article, and annealing the glass article.
Abstract:
Disclosed is a mask blank substrate for use in lithography, wherein the main surface on which the transfer pattern of the substrate is formed has a root mean square roughness (Rms) of not more than 0.15 nm obtained by measuring an area of 1 μm×1 μm with an atomic force microscope, and has a power spectrum density of not more than 10 nm4 at a spatial frequency of not less than 1 μm−1.