Abstract: A method for producing a polytetrafluoroethylene powder, which includes subjecting tetrafluoroethylene to suspension polymerization in an aqueous medium to prepare a suspension-polymerized particle of non melt-processible polytetrafluoroethylene, drying the suspension-polymerized particle to prepare a dry particle, subjecting the dry particle to fluorine radical treatment to prepare a fluorine radical-treated particle, and crushing the fluorine radical-treated particle to produce a polytetrafluoroethylene powder. Also disclosed is a polytetrafluoroethylene formed article obtained by forming the polytetrafluoroethylene powder, as well as a polytetrafluoroethylene compression-molded article obtained by compression molding the polytetrafluoroethylene powder.

Abstract: A fluoride phosphor, a composition of which is represented by General Formula (1), in which in a case where a cumulative 50% value is denoted by D50 and a cumulative 90% value is denoted by D90 in a volume-based particle size distribution curve obtained by a laser diffraction scattering method, D50 is 0.1 to 9.5 ?m and D90 is 0.5 to 16 ?m. General Formula (1): A2M(1-f)F6:Mn4+n In General Formula (1), an element A is one or more alkali metal elements including K, an element M is a Si simple substance, a Ge simple substance, or a combination of Si and one or more elements selected from the group consisting of Ge, Sn, Ti, Zr, and Hf, and 0<n?0.1 is satisfied.

Abstract: A potassium hexafluoromanganate is represented by General Formula: K2MnF6, and a diffuse reflectance with respect to light having a wavelength of 310 nm is 20% or more.

Abstract: A potassium hexafluoromanganate is represented by General Formula: K2MnF6, and a diffuse reflectance with respect to light having a wavelength of 550 nm is 60% or more.

Abstract: Provided is a fluoride phosphor that has a good external quantum efficiency and is suitable for stably producing white LEDs. The fluoride phosphor has a composition represented by a general formula (1) and a repose angle of 30° or more and 60° or less. general formula: A2M(1-n)F6:Mn4+n (1), wherein 0<n?0.1, the element A is one or more alkali metal elements including at least K, and the element M is a simple substance of Si, a simple substance of Ge, or a combination of Si and one or more elements selected from the group consisting of Ge, Sn, Ti, Zr, and Hf.

Abstract: Provided is a fluoride phosphor that has a good external quantum efficiency and is suitable for stably producing white LEDs. The fluoride phosphor having a composition represented by a general formula (1), a bulk density of 0.80 g/cm3 or more, and a mass median diameter (D50) of 30 ?m or less: general formula: A2M(1-n)F6:Mn4+n (1), wherein 0<n?0.1, the element A is one or more alkali metal elements including at least K, and the element M is a simple substance of Si, a simple substance of Ge, or a combination of Si and one or more elements selected from the group consisting of Ge, Sn, Ti, Zr, and Hf.

Abstract: Provided is a fluoride phosphor that has a good external quantum efficiency and is suitable for stably producing white LEDs. The fluoride phosphor having a composition represented by a general formula (1), a bulk density of 0.80 g/cm3 or more, and a mass median diameter (D50) of 30 ?m or less: general formula: A2M(1-n)F6:Mn4+n (1), wherein 0<n?0.1, the element A is one or more alkali metal elements including at least K, and the element M is a simple substance of Si, a simple substance of Ge, or a combination of Si and one or more elements selected from the group consisting of Ge, Sn, Ti, Zr, and Hf.

Abstract: The purpose of the present invention is to provide a fluoride phosphor (represented by the general formula A2SiF6:Mn) having high luminescence intensity and reliability, a high-luminance light-emitting device using this phosphor, and a production method for this phosphor. The production method for a fluoride phosphor represented by the general formula A2SiF6:Mn (where element A is an alkali metal element including at least potassium), wherein the fluoride phosphor production method comprises: a step of preparing an aqueous solution wherein element A and fluorine are dissolved in a solvent; and a step of adding, to the aqueous solution, solid silicon dioxide and a manganese compound that supplies manganese having a valence other than +7; wherein an added amount of the manganese compound is within a range such that an Mn content in the fluoride phosphor becomes at least 0.1 mass % and at most 1.

Abstract: The present invention relates to a process for producing a composite-fluoride fluorescent material represented by the general formula A2MF6:Mn4+ (wherein A is at least one alkali metal element including K; M is one or more metallic elements including at least Si or Ge and selected from among Si, Ge, Sn, Ti, Zr, and Hf; F is fluorine; and Mn is manganese). With the production process, it is possible to obtain a fluorescent material which is high in absorptance, internal quantum efficiency, and external quantum efficiency and has excellent optical properties.

Abstract: The purpose of the present invention is to provide a potassium fluoromanganate for use as a raw material for a manganese-activated complex fluoride phosphor, from which a manganese-activated complex fluoride phosphor having good fluorescence properties and reliability can be produced. The potassium fluoromanganate of the present invention is characterized in that, in an orbital electron binding energy spectrum diagram for manganese obtained by X-ray photoelectron spectroscopy, a ratio (signal intensity value A/signal intensity value B) between a signal intensity value A obtained by subtracting a background value from a maximum signal intensity value for binding energy values within the range from 643.0 eV or more to 644.0 eV or less, and a signal intensity value B obtained by subtracting the background value from a maximum signal intensity value for binding energy values within the range from 645.0 eV or more to 646.0 eV or less, is greater than 0 and no greater than 0.9.

Abstract: Provided is a fluoride phosphor that has a good external quantum efficiency and is suitable for stably producing white LEDs. The fluoride phosphor has a composition represented by a general formula (1) and a repose angle of 30° or more and 60° or less. general formula: A2M(1-n)F6:Mn4+n (1), wherein 0<n?0.1, the element A is one or more alkali metal elements including at least K, and the element M is a simple substance of Si, a simple substance of Ge, or a combination of Si and one or more elements selected from the group consisting of Ge, Sn, Ti, Zr, and Hf.

Abstract: Provided is a fluoride phosphor that has a good external quantum efficiency and is suitable for stably producing white LEDs. The fluoride phosphor having a composition represented by a general formula (1), a bulk density of 0.80 g/cm3 or more, and a mass median diameter (D50) of 30 ?m or less: general formula: A2M(1?n)F6:Mn4+n (1), wherein 0<n?0.1, the element A is one or more alkali metal elements including at least K, and the element M is a simple substance of Si, a simple substance of Ge, or a combination of Si and one or more elements selected from the group consisting of Ge, Sn, Ti, Zr, and Hf.

Abstract: Provided is a fluoride phosphor having a composition represented by the general formula (1): A2SiF6:Mn4+??(1) in which A represents at least one alkali metal comprising at least K. The fluoride phosphor has a ratio (A1/A2) of an area (A1) of a spectrum in a range of from 637 eV or more to less than 645 eV in XPS measurement to an area (A2) of a spectrum in a range of from 682.8 eV or more to less than 690 eV in XPS measurement, of 0.0008 to 0.0025.

Abstract: Provided is a fluoride phosphor having a composition represented by the general formula (1): A2SiF6:Mn4+??(1) in which A represents at least one alkali metal comprising at least K. The fluoride phosphor has a ratio (A1/A2) of an area (A1) of a spectrum in a range of from 645 eV or more to less than 651 eV in XPS measurement to an area (A2) of a spectrum in a range of from 682.8 eV or more to less than 690 eV in XPS measurement, of 0.0005 to 0.0010.

Abstract: Provided is a fluoride phosphor having a composition represented by the general formula (1): A2SiF6:Mn4+??(1) in which A represents at least one alkali metal comprising at least K. The fluoride phosphor has a ratio (A1/A2) of an area (A1) of a spectrum in a range of from 637 eV or more to less than 645 eV in XPS measurement to an area (A2) of a spectrum in a range of from 682.8 eV or more to less than 690 eV in XPS measurement, of 0.0008 to 0.0025.

Abstract: The purpose of the present invention is to provide a fluoride phosphor (represented by the general formula A2SiF6:Mn) having high luminescence intensity and reliability, a high-luminance light-emitting device using this phosphor, and a production method for this phosphor. The production method for a fluoride phosphor represented by the general formula A2SiF6:Mn (where element A is an alkali metal element including at least potassium), wherein the fluoride phosphor production method comprises: a step of preparing an aqueous solution wherein element A and fluorine are dissolved in a solvent; and a step of adding, to the aqueous solution, solid silicon dioxide and a manganese compound that supplies manganese having a valence other than +7; wherein an added amount of the manganese compound is within a range such that an Mn content in the fluoride phosphor becomes at least 0.1 mass % and at most 1.

Abstract: The purpose of the present invention is to provide a potassium fluoromanganate for use as a raw material for a manganese-activated complex fluoride phosphor, from which a manganese-activated complex fluoride phosphor having good fluorescence properties and reliability can be produced. The potassium fluoromanganate of the present invention is characterized in that, in an orbital electron binding energy spectrum diagram for manganese obtained by X-ray photoelectron spectroscopy, a ratio (signal intensity value A/signal intensity value B) between a signal intensity value A obtained by subtracting a background value from a maximum signal intensity value for binding energy values within the range from 643.0 eV or more to 644.0 eV or less, and a signal intensity value B obtained by subtracting the background value from a maximum signal intensity value for binding energy values within the range from 645.0 eV or more to 646.0 eV or less, is greater than 0 and no greater than 0.9.

Abstract: Provided is a phosphor that emits red light, is represented by the general formula, A2MF6:Mn, and exhibits little reduction in intensity even when exposed to a high-temperature, high-humidity atmosphere over a long period of time. Also provided is a light-emitting device using said phosphor. The present invention is a phosphor in which the main crystal phase thereof is represented by the general formula, A2MF6:Mn. The element A is an alkali metal element including at least K, and the element M is one or more tetravalent elements selected from the group consisting of Si, Ge, Sn, Ti, Zr, and Hf. The phosphor has a coating layer on the surface thereof. The coating layer is a hydrophobic organic substance having a hydrophobicity of 10% or more.

Abstract: The present invention relates to a process for producing a composite-fluoride fluorescent material represented by the general formula A2MF6:Mn4+ (wherein A is at least one alkali metal element including K; M is one or more metallic elements including at least Si or Ge and selected from among Si, Ge, Sn, Ti, Zr, and Hf; F is fluorine; and Mn is manganese). With the production process, it is possible to obtain a fluorescent material which is high in absorptance, internal quantum efficiency, and external quantum efficiency and has excellent optical properties.

Abstract: Provided is a method for producing a phosphor, using a nitride raw material, that gives a high-reliability (Sr,Ca)AlSiN3-based nitride phosphor at a productivity higher than before. The method comprises a mixing step of mixing raw materials and a calcining step of calcining the mixture obtained in the mixing step and, in producing the phosphor having a crystalline structure substantially identical with that of (Sr,Ca)AlSiN3 crystal as the host crystal, a strontium nitride containing SrN, Sr2N, or the mixture thereof as the main crystalline phase, as determined by crystalline phase analysis by powder X-ray diffractometry, and having a nitrogen content of 5 to 12 mass % is used as part of the raw materials.