Abstract: Provided are a method for producing a ceramic sintered body having improved light emission intensity, a ceramic sintered body, and a light emitting device. The method for producing a ceramic sintered body comprises preparing a molded body that contains a nitride fluorescent material having a composition containing: at least one alkaline earth metal element M1 selected from the group consisting of Ba, Sr, Ca, and Mg; at least one metal element M2 selected from the group consisting of Eu, Ce, Tb, and Mn; Si; and N, wherein a total molar ratio of the alkaline earth metal element M1 and the metal element M2 in 1 mol of the composition is 2, a molar ratio of the metal element M2 is a product of 2 and a parameter y and wherein y is in a range of 0.001 or more and less than 0.

Abstract: A nitride phosphor having a composition containing Eu, Si, Al, N, and a group 2 element including at least one selected from the group consisting of Mg, Ca, Sr, and Ba. In the composition, a ratio of a total molar content of the group 2 element and Eu to a molar content of Al is 0.8 or more and 1.1 or less, a molar ratio of Eu is 0.002 or more and 0.08 or less, a molar ratio of Si is 0.8 or more and 1.2 or less, and a total molar ratio of Si and Al is 1.8 or more and 2.2 or less. The nitride phosphor has a first peak in a range of 17° 2? or more and 19° 2? or less and a second peak in a range of 34° 2? or more and 35.5° 2? or less in a CuK? powder X-ray diffraction pattern.

Abstract: Provided are silicon-containing aluminum nitride particles having a high reflectance, a method for producing the same, and a light emitting device. In certain embodiment, silicon-containing aluminum nitride particles having a total amount of aluminum and nitrogen of 90% by mass or more, a content of silicon in a range of 1.5% by mass or more and 4.0% by mass or less, and a content of oxygen in a range of 0.5% by mass or more and 2.0% by mass or less, and having an average reflectance in a wavelength range of 380 nm or more and 730 nm or less of 85% or more.

Abstract: Provided are silicon-containing aluminum nitride particles having a high reflectance, a method for producing the same, and a light emitting device. In certain embodiment, silicon-containing aluminum nitride particles having a total amount of aluminum and nitrogen of 90% by mass or more, a content of silicon in a range of 1.5% by mass or more and 4.0% by mass or less, and a content of oxygen in a range of 0.5% by mass or more and 2.0% by mass or less, and having an average reflectance in a wavelength range of 380 nm or more and 730 nm or less of 85% or more.

Abstract: Provided are a chlorosilicate fluorescent material having high light emission efficiency, a method for producing the same, and a light emitting device. In certain embodiments, the chlorosilicate fluorescent material has a chemical composition comprising Ca, Eu, Mg, Si, O, and Cl, wherein when a molar ratio of Si in 1 mol of the chemical composition is set as 4, the chlorosilicate fluorescent material comprises Ca in a molar ratio range of 7.0 or more and 7.94 or less, Eu in a molar ratio range of 0.01 or more and 1.0 or less, Ca and Eu in a total molar ratio range of 7.70 or more and 7.95 or less, Mg in a molar ratio range of 0.9 or more and 1.1 or less, and Cl in a molar ratio range of more than 1.90 and 2.00 or less.

Abstract: Provided a method of producing a ?-sialon fluorescent material having excellent emission intensity. The method includes providing a first composition containing aluminum, an oxygen atom, and a europium-containing silicon nitride, heat treating the first composition, contacting the heat-treated composition and a basic substance to obtain a second composition, and contacting the second composition resulting from contacting the heat-treated composition with the basic substance and an acidic liquid medium containing an acidic substance.

Abstract: Provided is a light emitting device, including a first light emitting element having a light emission peak wavelength within a range of 400 nm or more and 490 nm or less, a second light emitting element having a different light emission peak wavelength from the first light emitting element within a range of 400 nm or more and 490 nm or less, a first fluorescent material that is excited by at least one of the first light emitting element and the second light emitting element and emits light having a light emission peak wavelength within a range of 500 nm or more and 540 nm or less, and a second fluorescent material, wherein the first fluorescent material is a Ce-activated aluminate fluorescent material containing Lu, Al, and Ga, and optionally at least one element selected from rare earth elements other than Lu.

Abstract: Provided are a chlorosilicate fluorescent material having high light emission efficiency, a method for producing the same, and a light emitting device. In certain embodiments, the chlorosilicate fluorescent material has a chemical composition comprising Ca, Eu, Mg, Si, O, and Cl, wherein when a molar ratio of Si in 1 mol of the chemical composition is set as 4, the chlorosilicate fluorescent material comprises Ca in a molar ratio range of 7.0 or more and 7.94 or less, Eu in a molar ratio range of 0.01 or more and 1.0 or less, Ca and Eu in a total molar ratio range of 7.70 or more and 7.95 or less, Mg in a molar ratio range of 0.9 or more and 1.1 or less, and Cl in a molar ratio range of more than 1.90 and 2.00 or less.

Abstract: A nitride phosphor having a composition containing Eu, Si, Al, N, and a group 2 element including at least one selected from the group consisting of Mg, Ca, Sr, and Ba. In the composition, a ratio of a total molar content of the group 2 element and Eu to a molar content of Al is 0.8 or more and 1.1 or less, a molar ratio of Eu is 0.002 or more and 0.08 or less, a molar ratio of Si is 0.8 or more and 1.2 or less, and a total molar ratio of Si and Al is 1.8 or more and 2.2 or less. The nitride phosphor has a first peak in a range of 17° 2? or more and 19° 2? or less and a second peak in a range of 34° 2? or more and 35.5° 2? or less in a CuK? powder X-ray diffraction pattern.

Abstract: A nitride phosphor having a composition containing Eu, Si, Al, N, and a group 2 element including at least one selected from the group consisting of Mg, Ca, Sr, and Ba. In the composition, a ratio of a total molar content of the group 2 element and Eu to a molar content of Al is 0.8 or more and 1.1 or less, a molar ratio of Eu is 0.002 or more and 0.08 or less, a molar ratio of Si is 0.8 or more and 1.2 or less, and a total molar ratio of Si and Al is 1.8 or more and 2.2 or less. The nitride phosphor has a first peak in a range of 17° 2? or more and 19° 2? or less and a second peak in a range of 34° 2? or more and 35.5° 2? or less in a CuK? powder X-ray diffraction pattern.

Abstract: Provided is a phosphor having superior light-emitting properties. A phosphor composition includes: a nitride phosphor that contains, in a composition thereof, an element M that is at least one selected from the group consisting of rare earth elements except cerium, silicon, nitrogen, and cerium; and an oxyfluoride. In the phosphor composition, a content of the oxyfluoride relative to the phosphor composition is 1.5% by mass or higher and 10% by mass or lower according to an X-ray diffraction reference intensity ratio method.

Abstract: A light emitting device includes a light emitting element having a dominant wavelength in a range of 400 nm or more and 500 nm or less, and a wavelength conversion member that is arranged on a light emitting side of the light emitting element and includes a rare earth aluminate fluorescent material having a composition represented by the following formula (I), wherein the light emitting device emits light having a dominant wavelength in a range of 475 nm or more and 500 nm or less, and wherein the light emitting device emits light having an S/P ratio of 6.5 or less derived from the formula (1), which is the ratio of a luminous flux in scotopic vision relative to a luminous flux in photopic vision: (Lu1-p-nLnpCen)3(Al1-mGam)5kO12??(I) wherein in the formula (I), Ln represents at least one rare earth element selected from the group consisting of Y, La, Gd, and Tb, and the parameters k, m, n, and p satisfy 0.95?k?1.05, 0.05?m?0.70, 0.002?n?0.050, and 0?p?0.30, respectively.

Abstract: A wavelength conversion member including a wavelength conversion layer containing a fluoride phosphor, quantum dots, a surfactant, and a resin. The fluoride phosphor contains fluoride particles having a specific composition and having particle size values within specific ranges. The quantum dots include at least one selected from a first crystalline nanoparticle and a second crystalline nanoparticle. The first crystalline nanoparticle has a specific composition. When irradiated with light having a wavelength of 450 nm, the first crystalline nanoparticle emits light having an emission peak at a wavelength in a range from 510 nm to 535 nm, and a full width at half maximum of the emission peak of the first crystalline nanoparticle is in a range from 10 nm to 30 nm. The second crystalline nanoparticle includes a chalcopyrite-type crystalline structure, and a full width at half maximum of the emission peak of the second crystalline nanoparticle is 45 nm or less.

Abstract: A method for producing a rare earth aluminate fluorescent material, including: preparing, as raw materials, cerium oxide having a crystallite diameter in a range of 200 ? or more and 1,600 ? or less, a compound containing at least one kind of a rare earth element Ln selected from the group consisting of Y, La, Lu, Gd, and Tb, a compound containing Al, and depending on necessity a compound containing at least one kind of an element M1 selected from the group consisting of Ga and Sc, wherein a total molar ratio of the rare earth element Ln and cerium is 3, a total molar ratio of Al and the element M1 is a product of a parameter k in a range of 0.95 or more and 1.05 or less and 5, a molar ratio of cerium is a product of a parameter n in a range of 0.005 or more and 0.050 or less and 3, and a molar ratio of the element M1 is a product of a parameter m in a range of 0 or more and 0.02 or less, the parameter k, and 5; and subjecting a mixture of the raw materials to a heat treatment to provide a calcined product.

Abstract: Provided a method of producing a ?-sialon fluorescent material having excellent emission intensity. The method includes providing a first composition containing aluminum, an oxygen atom, and a europium-containing silicon nitride, heat treating the first composition, contacting the heat-treated composition and a basic substance to obtain a second composition, and contacting the second composition resulting from contacting the heat-treated composition with the basic substance and an acidic liquid medium containing an acidic substance.

Abstract: Provided is a method for producing a ?-sialon fluorescent material, comprising preparing a composition containing a silicon nitride that contains aluminium, oxygen, and europium; heat-treating the composition at a temperature in a range of 1300° C. or more and 1600° C. or less to obtain a heat-treated product; subjecting the heat-treated product to a temperature-decrease of from the heat treatment temperature to 1000° C. as a first temperature-decrease step; and subjecting the heat-treated product to a temperature-decrease of from 1000° C. to 400° C. as a second temperature-decrease step. The first temperature-decrease step has a temperature-decrease rate in a range of 1.5° C./min or more and 200° C./min or less, and the second temperature-decrease step has a temperature-decrease rate in a range of 1° C./min or more and 200° C./min or less.

Abstract: A wavelength conversion member including a wavelength conversion layer containing a fluoride phosphor, quantum dots, a surfactant, and a resin. The fluoride phosphor contains fluoride particles having a specific composition and having particle size values within specific ranges. The quantum dots include at least one selected from a first crystalline nanoparticle and a second crystalline nanoparticle. The first crystalline nanoparticle has a specific composition. When irradiated with light having a wavelength of 450 nm, the first crystalline nanoparticle emits light having an emission peak at a wavelength in a range from 510 nm to 535 nm, and a full width at half maximum of the emission peak of the first crystalline nanoparticle is in a range from 10 nm to 30 nm. The second crystalline nanoparticle includes a chalcopyrite-type crystalline structure, and a full width at half maximum of the emission peak of the second crystalline nanoparticle is 45 nm or less.

Abstract: A nitride phosphor having a composition containing Eu, Si, Al, N, and a group 2 element including at least one selected from the group consisting of Mg, Ca, Sr, and Ba. In the composition, a ratio of a total molar content of the group 2 element and Eu to a molar content of Al is 0.8 or more and 1.1 or less, a molar ratio of Eu is 0.002 or more and 0.08 or less, a molar ratio of Si is 0.8 or more and 1.2 or less, and a total molar ratio of Si and Al is 1.8 or more and 2.2 or less. The nitride phosphor has a first peak in a range of 17° 2? or more and 19° 2? or less and a second peak in a range of 34° 2? or more and 35.5° 2? or less in a CuK? powder X-ray diffraction pattern.

Abstract: Disclosed are a production method for a nitride fluorescent material, a nitride fluorescent material and a light emitting device. The production method is for producing a nitride fluorescent material that has, as a fluorescent material core, a calcined body having a composition containing at least one element Ma selected from the group consisting of Sr, Ca, Ba and Mg, at least one element Mb selected from the group consisting of Li, Na and K, at least one element Mc selected from the group consisting of Eu, Ce, Tb and Mn, and Al, and optionally Si, and N, and the method includes preparing a calcined body having the above-mentioned composition, bringing the calcined body into contact with a fluorine-containing substance, and subjecting it to a first heat treatment at a temperature of 100° C. or higher and 500° C.

Abstract: Provided is a method of producing a ?-sialon fluorescent material having a high light emission intensity and an excellent light emission luminance. The method includes preparing a calcined product having a composition of ?-sialon containing an activating element; grinding the calcined product to obtain a ground product; and heat-treating the ground product to obtain a heat-treated product. A specific surface area of the ground product is 0.2 m2/g or more.