Abstract: An optical glass for precision press molding that has desired optical constants, a low glass transformation point (Tg), and a devitrification temperature that is lower than a temperature of a glass melt, at which a viscosity suitable for forming of a preform material is obtained, is provided. The optical glass for precision press molding has a lanthanum borosilicate system glass having optical constants of refractive index (nd) within a range from 1.65 to 1.73 and Abbe number (&ngr;d) within a range from 50 to 60, a Tg within a range of 480-580° C. The optical glass for precision press molding has a devitrification temperature that is lower than a temperature of the glass melt when the glass melt has a viscosity &eegr; (poise) of log &eegr;=2.5. The optical glass for precision press molding has a specific composition range of SiO2—B2O3—La2O3—Y2O3—Ta2O5—CaO—Li2O system composition.

Abstract: There is provided an optical glass suitable for mold pressing having optical constants of a refractive index (nd) within a range from 1.60 to 1.69 and Abbe number (&ngr;d) within a range from 35 to 45, having a glass transition point (Tg) within a range from 400° C. to 500° C., being free from devitrification when the optical glass is held at a temperature which is higher by 100° C. than the glass transition point (Tg) for 30 minutes, and comprising in mass % on oxide basis: SiO2 20-less than 40% B2O3  5-20% Al2O3  0-5% ZrO2 more than 3%-15% Nb2O5 10-30% MgO + CaO  0-less than 5% in which MgO  0-less than 5% CaO  0-less than 5% SrO  0-10% BaO  0-10% ZnO  0-18% Li2O  1-15% Na2O  1-10% K2O  1-10% Sb2O3  0-1%.

Abstract: Glass-ceramics for a light filter capable of preventing variation of refractive index in a band-pass filter have a coefficient of thermal expansion within a range from 95×10−7/°C. to 140×10−7/°C. within a temperature range from −20° C. to +70° C. and, preferably, Young's modulus of 85 GPa and bending strength of 10 kg/mm2, and light transmittance for plate thickness of 10 mm of 60% or over within a wavelength range from 950 nm to 1600 nm. Predominant crystal phases of these glass-ceramics should preferably be (a) lithium disilicate and (b) one selected from the group consisting of &agr;-quartz, &agr;-quartz solid solution, &agr;-cristobalite and &agr;-cristobalite solid solution.

Abstract: A method for producing a crystallized glass member, the method includes: precisely polishing each surface of two or more crystallizable original glass components having an identical composition so that the polished surfaces to be brought into contact with each other have a flatness of &lgr; (633 nm) or less; heating the glass components to a first temperature in a glass transition region while the surfaces are brought into contact with each other so as to fuse the glass components; and heating an original glass member prepared by fusing the glass components at a second temperature which is higher than the first temperature in the glass transition region, so as to crystallize and bond the original glass member.

Abstract: There is provided a glass-ceramic substrate which is suitable for use as a light filter. The glass-ceramic has a Young's modulus (GPa) within a range from 95 to 120 and includes 5.3 to 8 weight percent (expressed on an oxide basis) of Al2O3. Tile glass ceramic substrate preferably has, as its predominant crystal phases, (a) lithium disilicate (Li2O·2SiO2) and b) at least one of &agr;-quartz (&agr;-SiO2) and &agr;-quartz solid solution (&agr;-SiO2 solid solution), has a specific gravity within a range from 2.4 to 2.6 and has a coefficient of thermal expansion within a range from 65×10−7/° C. to 130×10−7/° C. within a temperature range from −50° C. to +70° C.

Abstract: An optical glass includes SiO2; PbO; B2O3; not less than 0.1 mass % of TeO2; and not less than 0.4 mass % of Li2O.

Abstract: An optical glass has optical constants which are an refractive index (nd) of 1.70-1.75 and an Abbe number (&ngr;d) of 45.0-54.0; a glass transformation temperature (Tg) of 500-580° C. The glass has the following composition in mass percent of: SiO2 more than 5 to 15%; B2O3 20 to less than 30%; a total amount of SiO2+B2O3 more than 25 to 40%; La2O3 more than 21 to less than 30%; Y2O3 more than 5 to 15%; Gd2O3 0 to less than 10%; ZrO2 1-8%; Nb2O5 0.1-5%; Ta2O5 more than 5 to 12%; a total amount of ZrO2+Nb2O5+Ta2O5 7-20%; ZnO 0-10%; CaO 0-10%; SrO 0-5%; BaO 0-10%; a total amount of ZnO+CaO+SrO+BaO 5-15%; Li2O 1-8%; Sb2O3 0-1%; and As2O3 0-1%. Devitrification is not generated when the optical glass is kept at a temperature of 920° C. for two hours.

Abstract: An aluminosilicate transparent glass has corrosion resistance in the form of mass loss of 4.0 mg or below per 1cm2 of the surface of a specimen upon holding the specimen for five hours in sodium hydroxide solution having concentration of 300 mg(L under test pressure of 50 MPa at 250° C. The glass has a coefficient of thermal expansion within a range from 35×10−7/° C. to 50×10−7/° C. within a temperature range from 100° C to 300° C. The glass has also powdered glass mass loss rate of 0.1% or below in terms of water resistance, acid resistance and alkali resistance.

Abstract: A negative thermal expansion glass ceramic having a negative coefficient of thermal expansion, which is a sufficiently large absolute value in a temperature range of −40° C. to +160° C. and a method for producing the same are provided. The negative thermal expansion glass ceramic has a coefficient of thermal expansion of −25 to −100×10−7/° C. in the temperature range of −40° C. to +160° C., and comprises main crystalline phases which are one or more types selected from a group consisting of &bgr;-eucryptite solid solution (&bgr;-Li2O·Al2O3·2SiO2 solid solution), &bgr;-eucryptite (&bgr;-Li2O·Al2O3·2SiO2), &bgr;-quartz solid solution (&bgr;-SiO2 solid solution), and &bgr;-quartz (&bgr;-SiO2), wherein a total amount of crystals of the main crystalline phases can be 70 to 100% in mass percent.

Abstract: A negative thermal expansion glass ceramic having a negative coefficient of thermal expansion, which is a sufficiently large absolute value in a temperature range of −40° C. to +160° C. and a method for producing the same are provided. The negative thermal expansion glass ceramic has a coefficient of thermal expansion of −25 to −100×10−7/° C. in the temperature range of −40° C. to +160° C., and comprises main crystalline phases which are one or more types selected from a group consisting of &bgr;-eucryptite solid solution (&bgr;-Li2O.Al2O3.2SiO2 solid solution), &bgr;-eucryptite (&bgr;-Li2O.Al2O3.2SiO2), &bgr;-quartz solid solution (&bgr;-SiO2 solid solution), and &bgr;-quartz (&bgr;-SiO2), wherein a total amount of crystals of the main crystalline phases can be 70 to 100% in mass percent.

Abstract: A high rigidity glass-ceramic substrate is provided which contains, as a predominant crystal phase or phases, at least one crystal phase selected from the group consisting of enstatite (MgSiO3), enstatite solid solution (MgSiO3 solid solution), magnesium titanate (MgTi2O5) and magnesium titanate solid solution (MgTi2O5 solid solution), has fine crystal grains (preferably globular crystal grains) of precipitated crystal phases, has excellent melting property of a base glass, high resistivity to devitrification, easiness in polishing, excellent smoothness in the surface after polishing and has high Young's modulus capable of coping with a high speed rotation.

Abstract: A glass-ceramic substrate for an information storage medium made of a glass-ceramics having a crystal phase dispersed in a glass matrix has a ratio of crystal phase (the amount of crystal) in the glass-ceramics is within a range from 50 wt % to 70 wt % and crystal grains having an average crystal grain diameter within a range from 0.10 &mgr;m to 0.50 &mgr;m are exposed on the surface of the substrate. The glass-ceramics substrate has Young's modulus within a range from 95 GPa to 160 GPa, specific gravity within a range from 2.40 to 2.80, and a ratio of Young's modulus to specific gravity within a range from 39 GPa to 57 GPa. The glass-ceramic substrate has a surface microstructure in which respective crystal grains present in a surface portion of the substrate are fixed to the surface portion with half or more in volume of the respective crystal grains being exposed above the surface of the glass matrix.

Abstract: A glass ceramic comprises a main crystal phase which comprises at least one selected from a group consisting of &bgr;-eucryptite (&bgr;-Li2O.Al2O3.2SiO2), &bgr;-eucryptite solid solution (&bgr;-Li2O.Al2O3.2SiO2 solid solution), &bgr;-quartz (&bgr;-SiO2), and &bgr;-quartz solid solution (&bgr;-SiO2 solid solution), wherein an average grain size of the main crystal phase is less than 5 &mgr;m, and a coefficient of thermal expansion thereof is −30×10−7 to −90×10−7/° C. in a temperature range of −40° C. to +160° C., and a hysteresis of the coefficient of thermal expansion is not more than 20 ppm.

Abstract: Lithium ion conductive glass-ceramics comprise in mol %: P2O5 30-45% SiO2 0-15% GeO2 + TiO2 25-50% in which GeO2 0-50% TiO2 0-50% ZrO2 0-8% M2O3 0<-10% where M is an element or elements selected from the group consisting of In, Fe, Cr, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb and Lu Al2O3 0-12% Ga2O3 0-12% Li2O 10-25% and contain Li1+X(M, Al, Ga)X(Ge1−YTiY)2−X(PO4)3 (where 0<X≦0.8 and 0≦Y≦1.0) as a predominant crystal phase. A solid electrolyte, an electric cell and a gas sensor utilizing these glass-ceramics are also provided.

Abstract: There is provided a glass-ceramic composite electrolyte including a medium containing glass-ceramic powder impregnated with a non-aqueous electrolytic solution. There is also provided a lithium secondary cell having a positive electrode, a negative electrode and a separator in which the separator includes the above described composite electrolyte. The glass-ceramic powder consists of grains having an average grain diameter of 20 &mgr;m or below (calculated on the basis of volume), a maximum grain diameter of 44 &mgr;m or below and lithium ion conductivity of 1×10−4S·cm−1 or over. The glass-ceramic composite electrolyte has thickness of 100 &mgr;m or below and lithium ion conductivity of 1×10−5S·cm−1 or over.

Abstract: An optical glass comprises the following composition in mass percent of: SiO2 18-29%; PbO 68-78%; and TeO2 0.1-3.5%; wherein the glass has optical constants which are a refractive index (nd) having a range of 1.75 to 1.87 and an Abbe number (&ngr;b) having a range of 21 to 28; and a wavelength of a light transmitted through the glass having a thickness of 10±0.1 mm at a transmittance of 80% by including a reflection loss, is not more than 420 nm.

Abstract: Glass for a light filter capable of preventing variation of refractive index in a band-pass filter has a coefficient of thermal expansion within a range from 90×10−7/° C. to 120×10−7/° C. within a temperature range from −20° C. to +70° C. and, preferably, Young's modulus of 75GPa or over and Vickers hardness of 550 or over, and light transmittance for plate thickness of 10 mm of 90% or over within a wavelength range from 950 nm to 1600 nm.

Abstract: A high rigidity glass-ceramic substrate is provided which contains, as a predominant crystal phase or phases, at least one crystal phase selected from the group consisting of enstatite (MgSiO3), enstatite solid solution (MgSiO3 solid solution), magnesium titanate (MgTi2O) and magnesium titanate solid solution (MgTi2O5 solid solution), has fine crystal grains (preferably globular crystal grains) of precipitated crystal phases, has excellent melting property of a base glass, high resistivity to devitrification, easiness in polishing, excellent smoothness in the surface after polishing and has high Young's modulus capable of coping with a high speed rotation.

Abstract: There are provided glass-ceramics containing, as a predominant crystal phase or phases, at least one selected from the group consisting of &agr;-cristobalite, &agr;-cristobalite solid solution, &agr;-quartz and &agr;-quartz solid solution, containing substantially no lithium disilicate (Li2O·2SiO2), lithium silicate (Li2O·SiO2), &bgr;-spodumene, &bgr;-eucryptite, &agr;-quartz, mica or fluorrichterite, containing substantially no Cr ingredient or Mn ingredient, and having average linear thermal expansion coefficient within a range from +65×10−7/° C. to +140×10−7/° C. within a temperature range from −50° C. to +70° C., said predominant crystal phase or phases having an average crystal grain diameter of less than 0.10 &mgr;m. The glass-ceramics are suitable for use as a substrate for an information storage medium and also for use as a substrate for a light filter.

Abstract: Glass-ceramics fo a light filter capable of preventing variation of refractive index in a band-pass filter have a coefficient of thermal expansion within a range from 95×10−7/° C. to 140×10−7/° C. within a temperature range from −20° C. to +70° C. and, preferably, Young's modulus of 85 GPa and bending strength of 10 kg/mm2, and light transmittance for plate thickness of 10 mm of 60% or over within a wavelength range from 950 nm to 1600 nm. Predominant crystal phases of these glass-ceramics should preferably be (a) lithium disilicate and (b) one selected from the group consisting of &agr;-quartz, &agr;-quartz solid solution, &agr;-cristobalite and &agr;-cristobalite solid solution.