Abstract: A photocatalyst material and a photocatalyst device capable of generating hydrogen from water by radiation of sunlight at high efficiency. The photocatalyst material according to the present invention includes a nitride-based compound semiconductor obtained by replacement of part of Ga and/or Al by a 3d-transition metal. The nitride-based compound semiconductor has one or more impurity bands. A light absorption coefficient of the nitride-based compound semiconductor is 1,000 cm?1 or more in an entire wavelength region of 1,500 nm or less and 300 nm or more. Further, the photocatalyst material satisfies the following conditions: the energy level of the bottom of the conduction band is more negative than the redox potential of H+/H2; the energy level of the top of the valence band is more positive than the redox potential of O2/H2O; and there is no or little degradation of a material even when the material is irradiated with light underwater.

Abstract: A photocatalyst material and a photocatalyst device capable of generating hydrogen from water by radiation of sunlight at high efficiency. The photocatalyst material according to the present invention includes a nitride-based compound semiconductor obtained by replacement of part of Ga and/or Al by a 3d-transition metal. The nitride-based compound semiconductor has one or more impurity bands. A light absorption coefficient of the nitride-based compound semiconductor is 1,000 cm?1 or more in an entire wavelength region of 1,500 nm or less and 300 nm or more. Further, the photocatalyst material satisfies the following conditions: the energy level of the bottom of the conduction band is more negative than the redox potential of H+/H2; the energy level of the top of the valence band is more positive than the redox potential of O2/H2O; and there is no or little degradation of a material even when the material is irradiated with light underwater.

Abstract: A new light-absorbing material which can increase the conversion efficiency of a solar cell and a photoelectric conversion element using same are provided. The light-absorbing material of the present invention comprises a nitride-based compound semiconductor obtained by replacement of part of Al and/or Ga in a compound semiconductor expressed by a general formula Al1?yGayN (0?y?1) by at least one kind of 3d-transition metals, the nitride-based compound semiconductor having one or more impurity bands between a valence band and a conduction band, and whose light absorption coefficient over an overall wavelength region of not longer than 1500 nm and not shorter than 300 being not lower than 1000 cm?1.

Abstract: The invention is directed to an optical recording member including a thin film photosensitive layer provided on a base. The thin film photosensitive layer may vary between a low optical density state and a high optical density state when optical energy is applied thereto. This thin film photosensitive layer contains a first element which may be a metal or semimetal, a second element which is at least one selected from Te, Ge, Sn, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Mo, Rh, Pd, Ag, Cd, In, Ta, W, Pt, Au, Tl, Pb, Si, Sb, Bi, and an oxygen element. Part of the oyxgen element is bonded with the first element to form its oxide. The ratio x of the total number of atoms of the oxygen element to that of the first element, when the maximum valence of the first element in a stable oxide state is n, is according to the relation of 0<x>n/2. At least part of the second element exists in a non-oxide state. This thin film photosensitive layer is formed by a vacuum deposition or sputtering method.

Abstract: The invention is directed to an optical recording member including a thin film photosensitive layer provided on a base. The thin film photosensitive layer may vary between a low optical density state and a high optical density state when optical energy is applied thereto. This thin film photosensitive layer contains a first element which may be a metal or semimetal, a second element which is at least one selected from Te, Ge, Sn, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Mo, Rh, Pd, Ag, Cd, In, Ta, W, Pt, Au, Tl, Pb, Si, Sb, Bi, and an oxygen element. Part of the oxygen element is bonded with the first element to form its oxide. The ratio x of the total number of atoms of the oxygen element to that of the first element, when the maximum valence of the first element in a stable oxide state is n, is according to the relation of 0<x<n/2. At least part of the second element exists in a non-oxide state. This thin film photosensitive layer is formed by a vacuum deposition or sputtering method.

Abstract: The present invention relates to a method of producing an optical recording medium containing a thin film photosensitive layer provided on a board. When subjected to an optical energy, the optical density of this thin film photosensitive layer varies. Such optical recording medium is formed by the method of (a) mixing tellurium dioxide TeO.sub.2 and a reducing substance or substances, (b) heating the obtained mixture and causing part of the TeO.sub.2 to react with the reducing substance to obtain a sintered body and (c) obtaining a TeO.sub.2 compound thin film photosensitive layer on a board by evaporation and deposition, using the sintered body obtained in steps (a) and (b) as the vacuum deposition source. The optical recording medium possessing such a TeO.sub.2 compound thin film photosensitive layer may be used as both a one-time recording type medium and as an erasable type medium, capable of erasing the previously recorded information and recording new information in its place.

Abstract: An optical information recording medium comprising a substrate and a photosensitive thin layer consisting of Te, O and Pd. When exposed to optical energy, this thin layer is capable of undergoing a phase change by which an optical transmittance is changed. The addition of Pd results in an improvement of a response time to a great extent. This optical information recording medium is preferably made by a method using a Pd evaporation source and another source for Te+TeO.sub.2.

Abstract: An optical disk recording and reproducing system which uses an optical disk at least one side of which is formed with a spiral groove which has a V-shaped or inverted-trapezoid-shaped cross sectional configuration. Both the radially inward and outward sloped faces of the groove are used as recording tracks which are tracked or scanned with the spot of a light beam in the case of recording or reproduction.

Abstract: Disclosed in this invention is a recording medium characterized by forming on the support a recording layer containing a metastable sensitive substance which is an intermediate product of a reaction between a first colorless or light-colored material containing the S atoms released by light irradiation and a second colorless or light-colored material which develops color as it is sulfurized by said S atoms.

Abstract: The optical density and/or the reflectivity of a recording layer included in an optical disk is selectively changed to record information by irradiation with a semiconductor laser beam, while the recording layer may be covered with a suitable protective film. The thickness of the recording layer is so determined that it is able to record information by means of a continuous wave type semiconductor laser beam, while the optical absorption rate of the recording layer is adjusted by setting the percentages of particular additives. The recorded information may be reproduced by the application of a laser beam, the incident power of which is lower than that of the recording beam, to detect the reflected light.

Abstract: A process for producing a lithium borate thermoluminescent and fluorescent substance containing lithium borate as its main component which comprises heat-treating a mixture of Li.sub.2 B.sub.4 O.sub.7 powder and an activator element compound at a temperature under and neighboring the melting point of Li.sub.2 B.sub.4 O.sub.7, to provide a highly sensitive fluorescent substance which has good adherence to the substrate of a dosimeter.

Abstract: A phosphor for a thermoluminescent radiation dosimeter, comprising lithium tetraborate as a base material and copper as an activator. In addition to these components lithium octaborate may further be included as a base material, and silver as an activator. The phosphors according to the invention have an effective atomic number quite near to that of tissue, so that it is suitable for measuring the radiation dose absorbed by a tissue specimen. Further they exhibit emission a spectra peak at 368 m.mu. which is convenient for measuring the response of widely used photomultiplier tubes. The sensitivities to .gamma.-rays are also improved, compared to the known lithium borate phosphor.

Abstract: An optical information storage material having a substrate and a film deposited on the substrate, the state of said material can be changed from a low optical density state to a high optical density state by the application of electrical, optical or thermal energy. The major component of the film is GeO.sub.x1, SnO.sub.x1, SbO.sub.x2, TlO.sub.x2, BiO.sub.x2 or MoO.sub.x3 wherein 0 < x1 < 2.0, 0 < x2 < 1.5 and 0 < x3 < 3.0. The film can be a mixture of above-mentioned material and an additive for improving the properties thereof. The material is made by vacuum evaporating GeO.sub.2, SnO.sub.2, Sb.sub.2 O.sub.3, Tl.sub.2 O.sub.3, Bi.sub.2 O.sub.3 or MoO.sub.3 under deoxidization conditions.

Abstract: An optical information storage material having a transparent base and a film deposited on the base, the state of which can be changed between a low optical density state and a high optical density state by the application of electrical, optical or thermal energy. The film is a tellurium oxide having the composition TeO.sub.x1 in which 0<x1<2.0, or a mixture of such a tellurium oxide and vanadium oxide for making it easier to change the state of the film material, or tellurium oxide and lead oxide for increasing the sensitivity of the film. The material is made by vacuum evaporating and depositing the tellurium oxide or the mixture of tellurium oxide with the vanadium or lead oxide from TeO.sub.2 or a solid solution of TeO.sub.2 and lead or vanadium oxide.