Abstract: A glass-ceramic suitable for use as a light filter includes, as a predominant crystal phase, lithium disilicate (Li2O.2SiO2) or a combination of lithium disilicate and at least one crystal phase selected from the group consisting of &agr;-quartz (&agr;-SiO2), &agr;-quartz solid solution (&agr;-SiO2 solid solution), &agr;-cristobalite (&agr;-SiO2) and &agr;-cristobalite solid solution (&agr;-SiO2 solid solution). This substrate has Young's modulus (GPa)/specific gravity of 37 or over, surface roughness Ra (arithmetic mean roughness) of 5.0 Å or below, a coefficient of thermal expansion within a temperature range from −50° C. to +70° C. which ranges from +65×10−7/° C. to +130×10−7/° C. and bending strength of 400 MPa or over.

Abstract: A glass-ceramic substrate for a magnetic information storage medium includes, as predominant crystal phases, lithium disilicate (Li2O.2SiO2) and at least one selected from a group consisting of &agr;-quartz (&agr;-SiO2), &agr;-quartz solid solution (&agr;-SiO2 solid solution), &agr;-cristobalite (&agr;-SiO2) and &agr;-cristobalite solid solution (&agr;-SiO2 solid solution) and has a coefficient of thermal expansion of +65 to +130×10−7/° C. at a temperature within a range from −50° C. to +70° C. and surface roughness (Ra) after polishing of 3 Å-9 Å.

Abstract: Glass-ceramics of 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 glass-ceramic substrate for a magnetic information storage medium having a super flat surface comprises, as a predominant phase or phases, at least one crystal phase selected from the group consisting of lithium disilicate (Li2O.2SiO2, having an interplaner spacing of maximum peak intensity measured by an X-ray diffraction analysis within a range from 3.57 Å and 3.62 Å), quartz (SiO2, having an interplaner spacing of maximum peak intensity measured by an X-ray diffraction analysis within a range from 3.33 Å to 3.41 Å), quartz solid solution (SiO2 solid solution, having an interplaner spacing of maximum peak intensity measured by an X-ray diffraction analysis within a range from 3.33 Å to 3.41 Å), cristobalite (SiO2, having an interplaner spacing of maximum peak intensity measured by an X-ray diffraction analysis within a range from 4.04 Å to 4.

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: A glass-ceramic substrate for a magnetic information recording medium contains, as a main crystal phase or phases, one or more crystal phases selected from the group consisting of &bgr;-quartz (&bgr;-SiO2), &bgr;-quartz solid solution (&bgr;-SiO2 solid solution), &bgr;-spodumene (&bgr;-Li2O.Al2O3.4SiO2), &bgr;-spodumene solid solution (&bgr;-Li2O.Al2O3.4SiO2 solid solution), &bgr;-eucryptite (&bgr;-Li2O.Al2O3.2SiO2, a part of Li2O being capable of being substituted by MgO and/or ZnO) and &bgr;-eucryptite solid solution (&bgr;-Li2O.Al2O3.2SiO2 solid solution, a part of Li2O being capable of being substituted by MgO and/or ZnO). Alternatively, the glass-ceramic contains, as a main crystal phase or phases, gahnite (ZnAl2O4) and/or gahnite solid solution (ZnAl2O4 solid solution). The glass-ceramic substrate has a high heat resisting property and a super flat surface capable of achieving a high recording density according to the perpendicular magnetic recording.

Abstract: There is provided a glass-ceramic substrate for an information storage medium usable in an information storage device of the ramp loading system. The glass ceramic substrate has a Young's modulus (GPa)/specific gravity of 37 or over and includes 5.3 to 8 weight percent (expressed on an oxide basis) of Al2O3. The glass ceramic substrate has, as its predominant crystal phases, lithium disilicate (Li2O.2SiO2) and &agr;-quartz (&agr;-SiO2), 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. and has a surface roughness (Ra) (arithmetic mean roughness) of 9 Å or below.

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 for a magnetic information storage medium has a ratio of Young's modulus to specific gravity within a range from 37 to 63 and comprises Al2O3 within a range from 10% to less than 20%. A predominant crystal phase of the glass-ceramic substrate consists of one or more crystals selected from the group consisting of &bgr;-quartz, &bgr;-quartz solid solution, enstatite, enstatite solid solution, forsterite and forsterite solid solution.

Abstract: There is provided a glass-ceramic substrate for a magnetic information storage medium having a data zone and a landing zone capable of stably lifting a magnetic head in the landing zone and also capable of reducing the amount of lifting of the magnetic head in the data zone for realizing a high recording density. The landing zone has a multiplicity of projections or depressions formed by irradiation of laser beam. A CO2 laser or a laser diode pumped solid-state laser can be used for this purpose. The surface roughness (Ra) of a polished surface of the landing zone is within a range from 3 Å to 9 Å, height of the projections or depressions is within a range from 50 Å to 300 Å, surface roughness (Ra) of the projections or depressions is within a range from 10 Å to 50 Å and interval of the projections or depressions is within a range from 10 &mgr;m to 200 &mgr;m.

Abstract: A solid electric cell includes a case, a negative electrode, a positive electrode and a solid electrolyte. The negative electrode, positive electrode and solid electrolyte are disposed in the case in such a manner that the negative electrode opposes the positive electrode through the solid electrolyte. The solid electrolyte is made of an alkali ion conductive glass-ceramic having ion conductivity no less than 10−3S/cm at room temperature. A gas sensor includes a case, a negative electrode, a positive electrode, a solid electrolyte and a layer for which an electromotive force corresponding to the concentration of the gas is produced between the two electrodes. In the case, the negative electrode opposes the positive electrode through the solid electrolyte. The solid electrolyte is made of an alkali ion conductive glass-ceramic having ion conductivity no less than 10−3S/cm at room temperature.

Abstract: A luminous glass comprising, in percent by weight, the following components: SiO2 46-66 Al2O3 18-30 MgO  0-12 CaO  0-16 ZnO  0-21 P2O5  0-10 Li2O 0-8 BaO 0-9 As2O3 + Sb2O3 0-2 wherein a ratio of Al2O3 to SiO2 is 0.32-0.56, a total amount of MgO, CaO, and ZnO is 2-34 wt. %, a total amount of P2O5, Li2O, and BaO is 0-21 wt. %, and one or more rare earth elements are added to the glass on an oxide basis of 0.1-30 wt. % to an total amount of the components, PbO, B2O3, BeO, Na2O, and K2O are not essentially contained, and the glass has a thermal shock resistance |&Dgr;t|° C. of not less than 150, which is obtained by following equation, |&Dgr;t|=[flexural strength]×(1−[Poisson's ratio])/([coefficient of thermal expansion]×[Young's modulus]).

Abstract: Long-lasting phosphorescent glasses and glass-ceramics have a composition containing 30-65 mol % SiO2 and 20-50 mol % ZnO as basic ingredients and may also contain, as an activator or an auxiliary activator, 0-5 mol % LnxOy where L n is an element or elements selected from the group consisting of Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Mn. In one aspect of the invention, long-lasting phosphorescent glass-ceramics have a composition containing 30-70 mol % SiO2, 5-40 mol % MgO and 10-55 mol % MO where M is an element or elements selected from the group consisting of Ca, Sr and Ba as basic ingredients. The composition further includes 0.0001-5 mol % Eu2O3 as an activator and 0.0001-6 mol % Ln2O3 as an auxiliary activator where Ln is an element or elements selected from the group consisting of Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.

Abstract: There is provided a glass-ceramic substrate for a magnetic information storage medium having a data zone and a landing zone capable of stably lifting a magnetic head in the landing zone and also capable of reducing the amount of lifting of the magnetic head in the data zone for realizing a high recording density. The landing zone has a multiplicity of projections or depressions formed by irradiation of laser beam. A CO2 laser or a laser diode pumped solid-state laser can be used for this purpose. The surface roughness (Ra) of a polished surface of the landing zone is within a range from 3 Å to 9 Å, height of the projections or depressions is within a range from 50 Å to 300 Å, surface roughness (Ra) of the projections or depressions is within a range from 10 Å to 50 Å and interval of the projections or depressions is within a range from 10 &mgr;m to 200 &mgr;m.

Abstract: There is provided a long-lasting phosphor having a base crystal of {dot over (a)}kermanite crystal structure consisting of R′ (where R′ is one or more elements selected from the group consisting of Ca, Sr and Ba), Mg, Si, O and N and comprising Eu as an activator and one or more co-activators such as Dy. The long-lasting phosphor is produced by sintering materials including strontium nitrate to grow the base crystal of {dot over (a)}kermanite crystal structure, or by changing a solution containing constituent elements or material in the state of suspension into fine particles of liquid by atomization and thereafter heating the fine particles of liquid in a gas stream under oxidating, neutral or reducing atmosphere. The new Mohs' scale of hardness of the long-lasting phosphor is less than 1. Phosphorescence brightness of the long-lasting phosphor 2 minutes after stoppage of irradiation of illuminance of 1000 lux for 30 minutes with a white fluorescent lamp is 200 mCd/m2 or over.

Abstract: There is provided a long-lasting phosphor being activated by divalent europium and having a chemical composition RO.a(Al1−xGax)2O3.bMmOn.cB2O3.dEu3+ (where R is at least one selected from the group consisting of alkaline-earth metals and Zn, and M is at least one selected from the group consisting of Y, Sc and Si) wherein a, b, c, d and x are within ranges of 0.3≦a≦8, 0<b≦0.2, 0.001≦c≦0.3, 0.001≦d≦0.3, and 0≦x<1.0.

Abstract: A high rigidity glass-ceramic substrate for a magnetic information storage medium has a ratio of Young's modulus to specific gravity within a range from 37 to 63 and comprises Al2O3 within a range from 10% to less than 20%. Predominant crystal phases of the glass-ceramic substrate consist of (1) cordierite or cordierite solid solution and (2) one or more crystals selected from the group consisting of Spinel crystal, Spinel crystal solid solution, enstatite, enstatite solid solution, &bgr;-quartz and &bgr;-quartz solid solution.

Abstract: A luminous glass ceramic comprising a main crystallized phase of spinel or a solid solution of spinel including the components in weight %: SiO2 30-65 Al2O3  5-35 MgO  1-20 BaO 3-4 ZnO  5-35 TiO2  1-15 As2O3 + Sb2O3 0-3 wherein one or more rare earth elements are added to the glass ceramic in an amount of 0.1-30 wt %.

Abstract: A magnetic head has a slider made of a glass-ceramic substrate which has, as its predominant crystal phase, a mixed crystal of lithium disilicate (Li2O.2SiO2) and either or both of &agr;-quartz (&agr;-SiO2) and &agr;-cristobalite (&agr;-SiO2), the &agr;-quartz has a globular grain structure each globular crystal grain being made of aggregated particles and having a grain diameter within a range from 0.1 &mgr;m to 3.0 &mgr;m, the &agr;-cristobalite has a globular grain structure each globular grain having a grain diamter within a range from 0.1 &mgr;m to 1.0 &mgr;m, and surface roughness (Ra) of the glass-ceramic substrate after polishing is within a range from 5 Å to 50 Å.

Abstract: A luminous glass ceramic comprising, in percent by weight, the following components: SiO2  50-65 (%) P2O5   0-10 Al2O3  18-30 Li2O   2-6 MgO 0.2-6 ZnO   0-2 CaO   0-4 BaO 0.5-6 TiO2   1-4 ZrO2   1-4 As2O3 + Sb2O3   0-2 wherein a total amount of SiO2 and P2O5 is 50-70 wt. %, a ratio of P2O5 to SiO2 is 0-0.18, a ratio of Al2O3 to SiO2 is 0.30-0.55, one or more rare earth elements are added to the glass ceramic on an oxide basis of 0.1-30 wt. % to an total amount of other components, Na2O component, K2O component, and PbO component are not essentially contained, and the glass ceramic has a thermal shock resistance |&Dgr;t|° C.