U.S. Philips Corporation

Hendrik J Joormann

Jan Haisma

Hendrik Verweij

Gijsbertus A Spierings

Theo J Popma

Alois J Van Gorp

Luminescent aluminoborate and/or aluminosilicate glass which is activated by one or more rare earth metals. The glass has a matrix comprising from 5 to 65 mol. % of one or more of the alkaline earth metal oxides BaO, SrO, CaO, ZnO and MgO, from 20 to 85 mol. % of B.sub.2 O.sub.3 and/or SiO.sub.2 and from 1 to 35 mol. % of Al.sub.2 O.sub.3. The glass contains as activator Tb.sup.3+ and/or Ce.sup.3+ in a quantity, calculated as Tb.sub.2 O.sub.3 and/or Ce.sub.2 O.sub.3, of 0.1 to 10 mol. % with respect to the matrix. The luminescent glasses have high conversion efficiencies, especially high quantum efficiencies upon UV excitation, and are preferably used in luminescent screens of, for example, discharge lamps or cathode-ray tubes.

Luminescent aluminoborate glass and luminescent screen provided with

A dielectric glass and a glass ceramic obtained therefrom is provided for separating crossing conductors in multilayer thick-film circuits. The dielectric glass has a composition in mol. % between the limits of 10-25% ZnO, 7.5-25% PbO, 50-60% SiO.sub.2, and 7.5-12.5% Al.sub.2 O.sub.3. These compositions are particularly suitable for conductor patterns having silver because they are free from micropores.

Dielectric glass in multilayer circuits and thick-film circuits

An optical fiber of germanium-free, multicomponent glasses has a core glass which has the molecular composition: SiO.sub.2 : 57.5-65%; (ZrO.sub.2 +1/2Y.sub.2 O.sub.3): 0-5%; (MgO+CaO+SrO+BaO+ZnO): 12.5-27.5 where MgO: 0-5%, CaO: 0-10%, SrO: 0-7.5%, BaO: 0-15% ZnO: 0-20%, and in which if no BaO is present, the ZnO content is 12.5-20%, and if no ZnO is present, the BaO content is 5-15%, and (Li.sub.2 O+Na.sub.2 O+K.sub.2 O): 10-25%. The core glass has a K.sub.2 O content which is preferably smaller than half of the total alkali metal oxide content. The cladding glass consists of a silicate glass or a borosilicate glass having a refractive index which is at least 2% lower than the refractive index of the core glass. The viscosity of the cladding glass at the processing temperature is 0.5 to twice the viscosity of the core glass expressed in Pa.s.

Germanium-free optical fibers having large numerical apertures

The invention relates to lamps having a glass lamp vessel (1) and to a glass suitable therefor. The relevant glass is adequately resistant to attack by electrons, is resistant to atmospheric influences and is properly workable in a gas flame. This glass contains 44-60 mole % silicon oxide; 0-7.5 mole % boron oxide; 0-6 mole % zirconium oxide; 0-7.5 mole % aluminium oxide; 5-20 mole % calcium oxide; 12.5-25 mole % barium oxide; 0-15 mole % magnesium oxide; 0-10 mole % strontium oxide; 2-8 mole % sodium oxide. The sum of the alkaline earth metals is 25-42.5 mole %. No discoloration occurs in sodium vapor discharge lamps when the lamp vessel has been made of this glass.

Lamp having a glass lamp vessel and Glass (Na-Ca-Ba-SiO.sub.2 with

Glasses consisting of 45-55 mol. % P.sub.2 O.sub.5, 15-40 mol. % BaO, 5-15 mol. % Li.sub.2 O, 5-35 mol. % PbO, 0-2 mol. % Al.sub.2 O.sub.3 and 0-6 mol. % F are suitable for the precision pressing of lenses.

Glass and glass objects

An optical fiber of the graded index type consisting of a glass having predominantly the composition 60-70 mole % SiO.sub.2, 15-30 mole % alkali metal oxides, and 10 to 15 mole % MgO in combination with at least one oxide selected from the group formed by CaO, SrO, BaO and ZnO. The impurity content of the fiber is less than 0.01 ppm. In the fiber the MgO content increases from the axis of the fiber to the circumference of the fiber. The oxide or the other oxides, having cations which can be exchanged for the magnesium cation, decrease to a corresponding extent in this direction.

Optical fiber of the graded index type and method of producing same

Glass objects, lenses in particular, can be pressed with precision from a glass which contains 45-55 mol. % P.sub.2 O.sub.5, 15-40 mol. % BaO, 5-15 mol. % Li.sub.2 O, 5-35 mol. % PbO, 0-2 mol. % Al.sub.2 O.sub.3 and 0-6 mol. % F.

Precision pressed glass object

Glass objects, lenses in particular, can be pressed with precision from a glass which contains 45-55 mol. % P.sub.2 O.sub.5, 15-40 mol. % BaO, 5-15 mol. % Li.sub.2 O, 5-35 mol. % PbO, 0-2 mol. % Al.sub.2 O.sub.3 and 0-6 mol. % F. A cube of glass is made from the above composition and preheated to a temperature of 20.degree.-60.degree. C. above the American softening point to obtain a polishing effect. The preheated cube is then inserted into preheated dies which are closed to form a precision pressed object of the glass.

Method of preparing precision pressed glass object

Magnetic head and method of producing a magnetic head which is formed by a core assembled from two pole pieces. At least one layer of a non-magnetizable material which forms the useful gap is provided between the pole pieces. One embodiment of the method includes the step of deposition on the pole pieces by means of a sputtering method a layer of a glass which comprises 12-20% by weight of Al.sub.2 O.sub.3, 40-48% by weight of B.sub.2 O.sub.3 and a total of 35-45% by weight of one or more of the oxides BaO, CaO or SrO. Thereafter the pole pieces are pressed together, with the glass layers in contact, and bonded together by heating the glass to the softening point, followed by cooling.

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Eindhoven, Netherlands

Hendrik J Joormann