Provided is a fluorine-containing synthetic silica glass powder which contains a sufficient amount of fluorine, and in which a reduction in the fluorine concentration caused by dissociation of fluorine from silica can be inhibited. Problems are solved by a fluorine-containing silica glass powder which contains particles having a particle size of more than 150 m but 300 m or less in an amount of 25% by weight or more as a whole. Also provided as a method of producing the glass powder is, for example, a method of producing a fluorine-containing silica glass powder, which method includes: prefiring a silicon oxide at a temperature of lower than 1,000 C. in the presence of SiF.sub.4 to prepare a fluorine-containing silica; and subsequently firing the fluorine-containing silica at a temperature of 1,000 C. or higher but lower than 1,400 C. to produce a silica glass powder.

Lithium silicate-low quartz glass ceramics are described which are characterized by a combination of very good mechanical and optical properties and can therefore be used in particular as restoration material in dentistry.

A glass-ceramic-ferrite composition contains glass, a ceramic filler, and NiZnCu ferrite. The glass contains about 0.5% by weight or more of R.sub.2O, where R is at least one selected from the group consisting of Li, Na, and K; about 5.0% by weight or less of Al.sub.2O.sub.3; about 10.0% by weight or more of B.sub.2O.sub.3; and about 85.0% by weight or less of SiO.sub.2 on the basis of the weight of the glass. The NiZnCu ferrite accounts for about 58% to 64% by weight of the glass-ceramic-ferrite composition. The ceramic filler contains quartz and, in some cases, forsterite. The quartz accounts for about 4% to 13% by weight of the glass-ceramic-ferrite composition. The forsterite accounts for about 6% by weight or less of the glass-ceramic-ferrite composition.

Glass compositions and glass fibers having low dielectric constants and low dissipation factors that may be suitable for use in electronic applications and articles are disclosed. The glass fibers and compositions of the present invention may include between 45.0 to 58.0 weight percent SiO.sub.2; greater than 18.0 weight percent B.sub.2O.sub.3 and no more than 26.0 weight percent B.sub.2O.sub.3; greater than 16.0 weight percent Al.sub.2O.sub.3 and no more than 23.0 weight percent Al.sub.2O.sub.3; between 0.25 to 12.0 weight percent P.sub.2O.sub.5; greater than 0.25 weight percent CaO and less than 5.00 weight percent CaO; less than 4.50 weight percent MgO; greater than 0.25 weight percent CaO+MgO and less than 5.00 weight percent CaO+MgO; less than 0.80 weight percent Fe.sub.2O.sub.3; and less than 0.50 weight percent TiO.sub.2. Further, the glass composition has a glass viscosity of 1000 poise at a temperature greater than 1350 degrees Celsius.

The present invention relates to glasses having a composition made up of base glasses. The glasses have a good chemical toughenability in combination with an advantageous coefficient of thermal expansion. Owing to their composition and the production process, the homogeneity of the properties of the glasses at their surface is high compared to the bulk glass. Furthermore, the fragility of the glasses is low, so that they can be processed to produce very thin glass articles.

A glass composition includes a base glass portion comprising: 65-75 wt % SiO.sub.2; 5-15 wt % CaO; 0-5 wt % MgO; 0-5 wt % K.sub.2O; 10-14 wt % Na.sub.2O; and 1-5 wt % Al.sub.2O.sub.3; wherein the glass composition has a ratio of Na.sub.2O to Al.sub.2O.sub.3 is in the range of 9.5-12.5 wt %/wt %.

The present invention relates to a method of producing a colored glass for a pharmaceutical container by which the transmittance of a glass to be obtained is easily controlled so as to satisfy the standards of the Japanese Pharmacopoeia.

A laser glass doped with high concentration of mid-infrared fluoroindate and a preparation method thereof are provided in the present application, belonging to the technical field of luminescent glass. The laser glass doped with high concentration of mid-infrared fluoroindate includes the raw materials in parts by mole percentage: 27-38 parts of InF.sub.3, 13 parts of ZnF.sub.2, 10 parts of GdF.sub.3, 19 parts of BaF.sub.2, 5 parts of CaF.sub.2, 10 parts of SrF.sub.2, 5-15 parts of Al(PO.sub.3).sub.3 and 1-11 parts of ErF.sub.3.

An alkali free glass has an average coefficient of thermal expansion at 50 to 350? C. of 30?10.sup.?7 to 43?10.sup.?7/? C., a Young's modulus of 88 GPa or more, a strain point of 650 to 725? C., a temperature T.sub.4 at which a viscosity reaches 10.sup.4 dPa.Math.s of 1,290? C. or lower, a glass surface devitrification temperature (T.sub.c) of T.sub.4+20? C. or lower, and a temperature T.sub.2 at which the viscosity reaches 10.sup.2 dPa.Math.s of 1,680? C. or lower. The alkali free glass contains, as represented by mol % based on oxides, 62 to 67% of SiO.sub.2, 12.5 to 16.5% of Al.sub.2O.sub.3, 0 to 3% of B.sub.2O.sub.3, 8 to 13% of MgO, 6 to 12% of CaO, 0.5 to 4% of SrO, and 0 to 0.5% of BaO. MgO+CaO+SrO+BaO is 18 to 22%, and MgO/CaO is 0.8 to 1.33.

Lithium silicate-low quartz glass ceramics are described which are characterized by a combination of very good mechanical and optical properties and can therefore be used in particular as restoration material in dentistry.