Abstract: The present invention relates to fine hollow powder with a titanium oxide shell, obtained by spray drying an exfoliated titania sol, and thin flaky titanium oxide powder obtained by pulverizing the fine hollow powder, and also to processes for producing the same. The present fine hollow powder and thin flaky titanium oxide powder have a distinguished dispersibility and are useful for additives to cosmetics, pigments, paints, etc., and the present fine hollow powder also has a distinguished flowability and is useful for seed particles for flow measurement.

Abstract: A method for separating metal ions, which comprises adding a selective capturing agent to an aqueous solution containing plural types of metal ions, said selective capturing agent being a cyclic compound and forming a complex with metal ions having ion radii suitable for the size of the ring alone, so that unnecessary metal ions are held by the selective capturing agent in the aqueous solution, and bringing said aqueous solution into contact with an ion exchange solid phase so as to transport desired metal ions alone to the solid phase.

Abstract: A multilayer ultrathin film which comprises layers of a polymer and layers of lamina particles alternately assembled, said lamina particles are obtained by exfoliating microcrystals of a layered titanium oxide.

Abstract: An optically functional device comprising a ferroelectric single crystal substrate and polarization-inverted structures formed at portions of the substrate at a temperature of not higher than the Curie temperature by an electron beam scanning irradiation method or a voltage application method and designed to control light passed through the polarization-inverted portions, wherein a LiNbO3 crystal having a molar ratio of Li/Nb within a range of from 0.95 to 1.01, is used as the substrate, so that the propagation loss of light passed through the polarization-inverted portions immediately after formation of the polarization-inverted structures, is not more than 2%.

Abstract: A silicon nitride sintered product comprising silicon nitride grains and a grain boundary phase, wherein the grain boundary phase consists essentially of a single phase of a Lu4Si2O7N2 crystal phase, and the composition of the silicon nitride sintered product is a composition in or around a triangle ABC having point A: Si3N4, point B: 28 mol % SiO2-72 mol % Lu2O3 and point C: 16 mol % SiO2-84 mol % Lu2O3, as three apexes, in a ternary system phase diagram of a Si3N4—SiO2—Lu2O3 system. Also disclosed is a silicon nitride sintered product comprising silicon nitride grains and a grain boundary phase of an oxynitride, wherein the composition of the sintered product is a composition in a triangle having point A: Si3N4, point B: 40 mol % SiO2-60 mol % Lu2O3 and point C: 60 mol % SiO2-40 mol % Lu2O3, as three apexes, in a ternary system phase diagram of a Si3N4—SiO2—Lu2O3 system.

Abstract: A single crystal of lithium niobate or lithium tantalate may be grown from a melt of a composition having a molar excess of Li compared to a melt having the stoichiometric amount of lithium, and having a molar fraction of Li2O/(Nb2O5+Li2O) or Li2O/(Ta2O5+Li2O) within a range of at least 0.490 and less than 0.500. The single crystal also has at least one element selected from the group consisting of Mg, Zn, Sc and In, in an amount of from 0.1 to 3.0 mol % based on the total amount of the elements, Nb and Li, or the total amount of the elements, Ta and Li.

Abstract: A photorefractive material provides a high photosensitivity without reduction. The material comprises a single crystal of terbium (Tb)-doped niobate or tantalate. The single crystal is a single crystal of lithium niobate (LiNbO3) whose molar fraction of [Li2O]/([Li2O]+[Nb2O5]) lies in a range of 0.482 to 0.505, or a single crystal of lithium tantalate (LiTaO3) whose molar fraction of [Li2O]/([Li2O]+[Ta2O5]) lies in a range of 0.482 to 0.505. The amount of terbium added in the photorefractive material ranges from 10 weight ppm to 1000 weight ppm.

Abstract: An optically functional device comprising a ferroelectric single crystal substrate and polarization-inverted structures formed at portions of the substrate at a temperature of not higher than the Curie temperature by an electron beam scanning irradiation method or a voltage application method and designed to control light passed through the polarization-inverted portions, wherein a LiTaO3 crystal having a molar ratio of Li/Ta within a range of from 0.95 to 1.02, is used as the substrate, so that the propagation loss of light passed through the polarization-inverted portions immediately after formation of the polarization-inverted structures, is not more than 2%.

Abstract: A method of treating a hollandite compound to improve its adsorption of nitrogen monoxide, which comprises subjecting a hollandite compound having a hollandite-type crystal structure and represented by a chemical formula AxMyN8-yO16, wherein A is an alkali metal or an alkaline earth metal K, Na, Rb or Ca, M is a bivalent or trivalent metal element Fe, Ga, Zn, In, Cr, Co, Mg, Al or Ni, N is a tetravalent metal element Sn or Ti, 0<x≦2 and 0<y≦2, to a heat treatment in a stream of an oxygen-nitrogen mixture having oxygen gas and nitrogen gas mixed in a volume ratio of 3:97 to 50:50, at a temperature of from 50 to 1,500° C. for from 5 minutes to 1 hour.

Abstract: A high pressure phase spinel type sialon represented by the chemical formula Si6−xAlxOxN8−x (0<x≦4.2), and a high pressure phase spinel type silicon oxynitride represented by the chemical formula Si3+xO2xN4 (═Si3N4.xSiO2, 0<x<1). Methods for their production by instantaneous pressing by means of an impulse wave.

Abstract: A silicon nitride sintered product comprising silicon nitride grains and a grain boundary phase, wherein the grain boundary phase consists essentially of a single phase of a Lu4Si2O7N2 crystal phase, and the composition of the silicon nitride sintered product is a composition in or around a triangle ABC having point A: Si3N4, point B: 28 mol % SiO2-72 mol % Lu2O3 and point C: 16 mol % SiO2-84 mol % Lu2O3, as three apexes, in a ternary system phase diagram of a Si3N4—SiO2—Lu2O3 system. Also disclosed is a silicon nitride sintered product comprising silicon nitride grains and a grain boundary phase of an oxynitride, wherein the composition of the sintered product is a composition in a triangle having point A: Si3N4, point B: 40 mol % SiO2-60 mol % Lu2O3 and point C: 60 mol % SiO2-40 mol % Lu2O3, as three apexes, in a ternary system phase diagram of a Si3N4—SiO2—Lu2O3 system.

Abstract: A method of quickly decomposing and removing an organic chlorine compound, which comprises coating a liquid containing an organic chlorine compound on the surface of a photocatalyst so that the liquid does not flow, said photocatalyst comprising a hollandite-type crystal phase represented by the formula: AxMyN8-yO16 (wherein A is at least one element selected from the group consisting of K, Rb, Cs, Ca, Ba and Na, M is a bivalent or trivalent metal element, N is an element which forms a rutile-type oxide, such as Ti, Sn or Mn, provided that A may be a Na element, only when M is Cr, and x and y satisfy 0.7<x≦2.0 and 0.7<y≦2.0, respectively), followed by irradiation with light in air so that the organic chlorine compound undergoes quick and complete oxidative destruction.

Abstract: A hologram recording apparatus is capable of directing interferable signal light and reference light into a hologram recording medium to record an information signal carried by the signal light. The hologram recording medium is sensitive to a first light at a first wavelength in an ultraviolet or short-wavelength visible light band to develop light induced absorption. The apparatus includes a light source for irradiating the hologram recording medium with the first light, and a laser light source for irradiating the hologram recording medium with signal light and reference light at a second wavelength longer than the first wavelength after the first light is irradiated.

Abstract: A two-color holographic recording apparatus reduces error signals possibly included in reproduced digital data signals. The two-color holographic recording apparatus has first, second and third light shutters for passing or blocking gate light, signal light and reference light incident on a recording medium respectively, and a controller for controlling the respective states of the first, second and third light shutters.

Abstract: A stoichiometric single crystal of lithium niobate or lithium tantalate is produced by pulling a single crystal of lithium niobate or lithium tantalate having a molar fraction of Li2O/(Nb2O5+Li2O) or Li2O/ (Ta2O5+Li2O) of at least 0.490 and less than 0.500, from a melt of a composition having a molar excess of Li over a stoichiometric composition of lithium niobate or lithium tantalate. The single crystal has 0.1 to 3 mol % of at least one element selected from the group consisting of Mg, Zn, Sc and In based on a total amount of elements Nb and Li, or a total amount of elements Ta and Li. The single crystal has substantially no absorption in the visible light region.

Abstract: A method for separating metal ions, which comprises adding a selective capturing agent to an aqueous solution containing plural types of metal ions, said selective capturing agent being a cyclic compound and forming a complex with metal ions having ion radii suitable for the size of the ring alone, so that unnecessary metal ions are held by the selective capturing agent in the aqueous solution, and bringing said aqueous solution into contact with an ion exchange solid phase so as to transport desired metal ions alone to the solid phase.

Abstract: Cubic boron nitride which is obtained from a gas phase without using an ultra-high pressure and which distinctly shows, in the Raman spectrum, either characteristic scattering by phonon of an optical longitudinal wave mode at 1305±15 cm−1 or characteristic scattering by phonon of an optical transverse wave mode at 1056±15 cm−1, or both characteristic scatterings.

Abstract: A silicon nitride sintered product comprising silicon nitride grains and a grain boundary phase, wherein the grain boundary phase consists essentially of a single phase of a LU4Si2O7N2 crystal phase, and the composition of the silicon nitride sintered product is a composition in or around a triangle ABC having point A: Si3N4, point B: 28 mol % SiO2-72 mol % LU2O3 and point C: 16 mol % SiO2-84 mol % LU2O3, as three apexes, in a ternary system phase diagram of a Si3N4—SiO2—LU2O3 system. Also disclosed is a silicon nitride sintered product comprising silicon nitride grains and a grain boundary phase of an oxynitride, wherein the composition of the sintered product is a composition in a triangle having point A: Si3N4, point B: 40 mol % SiO2-60 mol % LU2O3 and point C: 60 mol % SiO2-40 mol % LU2O3, as three apexes, in a ternary system phase diagram of a Si3N4-SiO2-LU2O3 system.

Abstract: A two-color hologram recording/reproducing apparatus is capable of directing interferable signal light and reference light into a hologram recording medium to record an information signal carried by the signal light. The hologram recording medium is sensitive to a first light at a first wavelength in an ultraviolet or short-wavelength visible light band to develop light induced absorption. The apparatus includes a light source for irradiating the hologram recording medium with the first light, a laser light source for irradiating the hologram recording medium with signal light and reference light at a second wavelength longer than the first wavelength after the first light is irradiated, and a gate light source for directing gate light at a third wavelength into the hologram recording medium.

Abstract: An optically functional device comprising a ferroelectric single crystal substrate and polarization-inverted structures formed at portions of the substrate at a temperature of not higher than the Curie temperature by an electron beam scanning irradiation method or a voltage application method and designed to control light passed through the polarization-inverted portions, wherein a LiTaO3 crystal having a molar ratio of Li/Ta within a range of from 0.95 to 1.02, is used as the substrate, so that the propagation loss of light passed through the polarization-inverted portions immediately after formation of the polarization-inverted structures, is not more than 2%.