Abstract: Substantially spherical particles of lithium silicates with improved mechanical properties and improved surface quality are provided, which are particularly suited for use as breeding material for tritium. The particles are characterised in that they contain additions of tellurium and/or tellurium compounds.

Abstract: Substantially spherical particles of lithium silicates with improved mechanical properties and improved surface quality are provided, which are particularly suited for use as breeding material for tritium. The particles are characterized in that they contain additions of tellurium and/or tellurium compounds.

Abstract: A chemically resistant glass which can be produced at relatively low melting temperatures and has anomalous negative partial dispersion P.sub.g,F, a refractive index n.sub.d of from 1.73 to 1.83 and an Abbe coefficient v.sub.d of from 31 to 38 preferably contains (in % by weight, based on oxides):______________________________________ 0-4 SiO.sub.2 + GeO.sub.2 0-2 GeO.sub.2 0-10 MgO 26-33 B.sub.2 O.sub.3 0-1 Li.sub.2 O 0-16 CaO 19-50 PbO 0-1 Na.sub.2 O 0-16 BaO 1-6 ZrO.sub.2 0-1 K.sub.2 O 0-16 SrO 4-16 Ta.sub.2 O.sub.5 0-2 .SIGMA. alkaline earth 0-6 Al.sub.2 O.sub.3 metal oxides 0-16 ZnO 0-4 TiO.sub.2 1.5-20 .SIGMA. alkaline earth metal oxides + ZnO 0-1 WO.sub.3 0-11 La.sub.2 O.sub.3 0-7 Nb.sub.2 O.sub.5 0-5.5 Y.sub.2 O.sub.3 0-5.5 Gd.sub.2 O.sub.3 4-11 .SIGMA. La.sub.2 O.sub.3 + Y.sub.2 O.sub.3 + Gd.sub.2 O.sub.3 ______________________________________with the proviso that the .SIGMA.(SiO.sub.2 +GeO.sub.2 +B.sub.2 O.sub.3)/.SIGMA.(ta.sub.2 O.sub.5 +ZrO.sub.2 +HfO.sub.2) ratio is less than 5 and the PbO/.

Abstract: A glass having a negative anomalous partial dispersion .DELTA.P.sub.g,F, an index of refraction of n.sub.d .gtoreq.1.67 and an Abbe number of .nu..sub.d >36 has the following composition, in % by weight, 3-11 of SiO.sub.2, 0-3 of GeO.sub.2, .SIGMA. SiO.sub.2 +GeO.sub.2, 4.5-11; B.sub.2 O.sub.3, 29-35; 5-13 of Al.sub.2 O.sub.3 ; 1-3 of ZrO.sub.2 ; 0.2-3 of TiO.sub.2 ; 0.2-1.5 of Ta.sub.2 O.sub.5 ; 30-45 of PbO; 0-3 each of Li.sub.2 O, Na.sub.2 O, K.sub.2 O, Rb.sub.2 O, Cs.sub.2 O, .SIGMA. alkali metal oxide 0-3; 0-3.5 each of MgO, CaO, BaO, SrO, .SIGMA. alkaline-earth oxide 0-6, if .SIGMA. SiO.sub.2 and GeO.sub.2 .gtoreq.9; .SIGMA. alkaline-earth oxide 0-3.5, if .SIGMA. SiO.sub.2 and GeO.sub.2 <9; 0-14 of ZnO, 0-3 of La.sub.2 O.sub.3 ; 0-7 of Nb.sub.2 O.sub.3 ; 0-1 of Sb.sub.2 O.sub.3 ; 0-0.3 of As.sub.2 O.sub.3 ; 0-1.5 of WO.sub.3 ; 0-1 of F. This glass is inexpensive and can be produced in high quality, and has a high crystalization stability and good transmission values.

Abstract: An optical glass, n.sub.d .gtoreq.1.60 and v.sub.d .gtoreq.58, having a high chemical stability as well as resistance to phase separation and crystallization, comprises in percent by weight:______________________________________ SiO.sub.2 21.5-27.0; B.sub.2 O.sub.3 23.5-30.0 SrO 16.0-24.0; La.sub.2 O.sub.3 10.0-20; Al.sub.2 O.sub.3 1.5-5.0; BaO 5.0-14.0; ZrO.sub.2 0-4.0; Li.sub.2 O 0.5-5.0; Na.sub.2 O 0.8-2.5; K.sub.2 O 0-2.0.

Abstract: A highly refractive optical glass (n.sub.d .gtoreq.1.83) with high dispersion (v.sub.d .ltoreq.25) and very good chemical stability at relatively low density (.delta..ltoreq.3.5 g/cm.sup.3) consists of (in weight percent) SiO.sub.2 19-25, Na.sub.2 O 7-10, K.sub.2 O 4-7, Cs.sub.2 O 0-12, Cao 0.5-2.0, BaO 9-15, TiO.sub.2 25-30, ZrO.sub.2 0-6, Nb.sub.2 O.sub.5 16-20, WO.sub.3 0-3, with Nb.sub.2 O.sub.5 :TiO.sub.2 =0.6-0.71.

Abstract: High PbO-content glass in the optical range of flint and heavy flint glasses from the system SiO.sub.2 --PbO--M.sub.2 O wherein M.sub.2 O=alkali metal oxides, said glass having a minimum PbO content of 30 wt. % and a minimum M.sub.2 O content of 0.5 wt. %, are provided with enhanced chemical stability without loss of the desired optical position by replacing a portion of the SiO.sub.2 and PbO such that the glass contains 1.5-6 wt. % (TiO.sub.2 +ZrO.sub.2) and the ratio of TiO.sub.2 :ZrO.sub.2 is about 0.3-2.0.

Abstract: An optical and ophthalmic glass with high refractive index, high Abbe number and low density, which is distinguished by good chemical stability, good crystallization behavior and capability of chemical hardening, comprises (in % by weight):______________________________________ SiO.sub.2 50-63 B.sub.2 O.sub.3 4-8 Al.sub.2 O.sub.3 1-2 Li.sub.2 O 4-8 Na.sub.2 O 4-8 K.sub.2 O 3-7 sum of M.sub.2 O 11-20 (M = Li, Na, K) MgO 0.5-2 CaO 2-5 sum of MO 0-3 (M = Mg, Ca) TiO.sub.2 8-12.5 ZrO.sub.2 1-3 F.sup.- 0-1 As.sub.2 O.sub.3 0.05-0.15 (optional refining agent) Sb.sub.2 O.sub.3 0.0-0.

Abstract: Optical glass with refractive indicies.gtoreq.1.90, Abbe numbers.gtoreq.25 consisting essentially of, in weight percent; 0-10 SiO.sub.2, 2-20 B.sub.2 O.sub.3, 0-2 Al.sub.2 O.sub.3, the sum of SiO.sub.2, B.sub.2 O.sub.3, and Al.sub.2 O.sub.3 being 7.5-25, 1-16 TiO.sub.2, 0-10 ZrO.sub.2, 35-55 La.sub.2 O.sub.3, 0.5-10 Y.sub.2 O.sub.5, 0.5-15 Nb.sub.2 O.sub.5, 0-10 Gd.sub.2 O.sub.3, 0-15 Ta.sub.2 O.sub.5, 0-3 P.sub.2 O.sub.5 wherein the ratio of SiO.sub.2 to B.sub.2 O.sub.3 is between 0.1 and 1.6, and the sum of Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 is from 9 to 20%.

Abstract: An optical and ophthalmic glass with high refractive index, high Abbe number and low density, which is distinguished by good chemical stability, good crystallization behavior and capability for chemical hardening, comprises (in % by weight):SiO.sub.2 --47 to 75B.sub.2 O.sub.3 --1 to 20Al.sub.2 O.sub.3 --0 to 10P.sub.2 O.sub.5 --0 to 5Li.sub.2 O--0 to 15Na.sub.2 O--0 to 10K.sub.2 O--0 to 10CaO--0 to 20MgO--0 to 15SrO--0 to 4BaO--0 to 4ZnO--0 to 5TiO.sub.2 --1 to 15ZrO.sub.2 --0 to 8Nb.sub.2 O.sub.5 --0 to 5 andF----0 to 5.

Abstract: An optical glass with the familiar optical position of n.sub.d >1.70 and v.sub.d >22, which differs from the familiar optical glasses of the optical position due to its lower density and good chemical stability, and is composed of (in percent by weight): SiO.sub.2 25-42, TiO.sub.2 15-35, B.sub.2 O.sub.3 0.5-7, BaO 3-13, CaO 1-3, Nb.sub.2 O.sub.5 1-20, GeO.sub.2 0-2, Al.sub.2 O.sub.3 0-4, Na.sub.2 O 7.5-15, Li.sub.2 O 0-9, K.sub.2 O 2-10, SrO 0-6, ZnO 0-5, ZrO.sub.2 0-3, and WO.sub.3 0-3.

Abstract: A spectacle glass which is colorless in the visible spectrum range, not transmissive in the ultraviolet spectrum range below 350 nm, has a refractive index n.sub.d higher than 1.56 and an Abbe number of more than 45, and which has an extremely low density, has the following composition (in % by weight):______________________________________ 12-40 P.sub.2 O.sub.5 13-34 Al.sub.2 O.sub.3 8-30 SiO.sub.2 0-16 B.sub.2 O.sub.3 4-12 TiO.sub.2 0-4 ZrO.sub.2 2-18 CaO 0-4 MgO 0-15 Na.sub.2 O 0-11 K.sub.2 O 0-6 Li.sub.2 O 0-12 Nb.sub.2 O.sub.5 0-8 ZnO.

Abstract: A new phototropic glass in which the phototropic properties arise from precipitations of silver halide and which in the unirradiated condition is slightly tinted or completely colorless while showing a brown color in the light-exposed condition, comprises, in known phototropic glass compositions, an additional content of at least 0.001 wt % of TeO.sub.2 and/or Yb.sub.2 O.sub.3.

Abstract: CdO- and ThO-free, highly refractive optical glass having a refractive index of 1.85-2.05 and an Abbe index of 25-43, characterized by the following composition (in percent by weight):______________________________________ SiO.sub.2 5-15 B.sub.2 O.sub.3 2.5-8 SiO.sub.2 + B.sub.2 O.sub.3 7-23 SiO.sub.2 /B.sub.2 O.sub.3 1.3-2.1 La.sub.2 O.sub.3 43-56 Gd.sub.2 O.sub.3 0-14 La.sub.2 O.sub.3 + Gd.sub.2 O.sub.3 43-60 ZrO.sub.2 3-10 Nb.sub.2 O.sub.5 0-15 Ta.sub.2 O.sub.5 0-20 Nb.sub.2 O.sub.5 + Ta.sub.2 O.sub.

Abstract: A borosilicate glass composition suitable for use as an eyeglass lens, characterized by having a refractive index nd.gtoreq.1.58, an Abbe number vd.gtoreq.45, a density .rho..ltoreq.2.75 g/cm.sup.3, and an excellent aptitude for chemical hardening, consisting essentially of the following composition, in weight percent:______________________________________ SiO.sub.2 51-65 B.sub.2 O.sub.3 2-14 Al.sub.2 O.sub.3 0-5 SiO.sub.2 + B.sub.2 O.sub.3 + Al.sub.2 O.sub.3 62-73 Li.sub.2 O 4-13 Na.sub.2 O 0-4 K.sub.2 O 0-4 Li.sub.2 O + Na.sub.2 O + K.sub.2 O 7-15 CaO 1-19 MgO 0-11 CaO + MgO 6-22 TiO.sub.2 0-8 ZrO.sub.2 0-9.

Abstract: An improved optical glass having an index of refraction of .gtoreq.1.69, an Abbe number of .gtoreq.38, and a density of .ltoreq.3.25 g/cm.sup.3, represents a further development of another optical glass recently provided by the same inventors. The new glass has improved suitability for continuous-tank manufacture and increased acidproofness and differs from the other glass in its content of 0.5-4.0% by weight of P.sub.2 O.sub.5 ; its sum total of SiO.sub.2 +B.sub.2 O.sub.3 +Al.sub.2 O.sub.3 +P.sub.2 O.sub.5 being 38.5-41.5% by weight; and its sum total of MgO+CaO being 13-17.5% by weight. The full glass composition, e.g. is in % by weight:______________________________________ SiO.sub.2 26.0-32.5 B.sub.2 O.sub.3 6.0-12.0 Al.sub.2 O.sub.3 0-3.0 P.sub.2 O.sub.5 0.5-4.0 SiO.sub.2 + B.sub.2 O.sub.3 + Al.sub.2 O.sub.3 + P.sub.2 O.sub.5 = 38.5-41.5 Li.sub.2 O 0-5 Na.sub.2 O 0-6 K.sub.2 O 0-8 Li.sub.2 O + Na.sub.2 O + K.sub.2 O = 4.5-12.0 MgO 0-8 CaO 9-16 MgO + CaO = 13-17.

Abstract: An optical and ophthalmic glass having an index of refraction of .gtoreq.1.69, an Abbe number of .gtoreq.37, and a density of .ltoreq.3.30 g/cm.sup.3, consists essentially of (in % by weight):______________________________________ SiO.sub.2 18-36 B.sub.2 O.sub.3 3-18 GeO.sub.2 0-8 Al.sub.2 O.sub.3 0-6, wherein SiO.sub.2 + B.sub.2 O.sub.3 + Al.sub.2 O.sub.3 + GeO.sub.2 25-39 P.sub.2 O.sub.5 0-14, wherein SiO.sub.2 + B.sub.2 O.sub.3 + Al.sub.2 O.sub.3 + GeO.sub.2 + P.sub.2 O.sub.5 = 30-44 Li.sub.2 O 0-12 Na.sub.2 O 0-14 K.sub.2 O 0-18 Li.sub.2 O + Na.sub.2 O + K.sub.2 O = 2-18 MgO 0-15 CaO 7-25 MgO + CaO 15-32 SrO 0-13 BaO 0-17 ZnO 0-15 PbO 0-10 SrO + BaO + ZnO + PbO 0-20 TiO.sub.2 3-14 Nb.sub.2 O.sub.5 0-13 WO.sub.3 0-10 TiO.sub.2 + Nb.sub.2 O.sub.5 + WO.sub.3 = 10-21 ZrO.sub.2 0-15, La.sub.2 O.sub.3 0-20 Y.sub.2 O.sub.3 0-16 Gd.sub.2 O.sub.3 0-16 Yb.sub.2 O.sub.3 0-10 La.sub.2 O.sub.3 + Y.sub.2 O.sub.3 + Gd.sub.2 O.sub.3 + Yb.sub.2 O.sub.3 = 0-20 Ta.sub.2 O.sub.5 0-13 HfO.sub.2 0-5 SnO.sub.2 0-6.

Abstract: A glass having a high refractive index, preferably >1.77, and a low specific gravity, preferable .ltoreq.3.8, is provided for utilization as spectacle lenses. The glass consists essentially of 80 mol percent or more of light cationic oxides with the remainder being cationic oxides having a greater molecular weight. It has a high crystallization stability in a viscosity range >200 poises and an expansion coefficient .alpha..times.10.sup.7 between 20.degree.-300.degree. C. of .ltoreq.100. Sufficiently light in weight to be well-suited for use as spectacle lenses, the glass can be continuously produced, as it has no pronounced tendency toward crystallization. The resulting corrective optical lenses have relatively high dioptric values, even with small center and edge thicknesses.

Abstract: Optical glasses having high refractive indexes and low specific gravities are provided for use as both distant and near vision spectacle lenses. The glasses consist essentially of low molecular weight cationic oxides, alkali metal oxides and divalent oxides to promote the crystallization stability of the glass. They have good chemical resistance, chemical hardenability and a thermal expansion coefficient between 93 and 99.times.10.sup.-7 /.degree. C. in the range of 20.degree.-300.degree. C. Optical lenses can be continuously produced due to the high crystallization stability of the glasses and the resultant spectacle lenses have high dioptric values even with thinner edge or center thicknesses.