A fiber optic plate 122 including a plurality of core glasses 122a, a clad glass 122b covering the core glass 122a, and a light-absorbing glass 122c disposed between the plurality of core glasses 122a, wherein a content of TiO.sub.2 in the core glass 122a is 7% by mass or less, a content of B.sub.2O.sub.3 in the core glass 122a is 15% by mass or more, and a content of WO.sub.3 in the core glass 122a is more than 0% by mass.

A method of forming a perovskite thin film and a light-emitting device including a layer manufactured by the method.

A process for the dry synthesis of a luminophore of formula A.sub.x[BF.sub.y]:C includes a stage of providing an initial composition comprising at least two synthetic precursors and at least one chemical doping source, a stage of heating the initial composition up to a fluorination temperature under an inert atmosphere or under vacuum, a stage of treatment under a fluorine atmosphere of the composition obtained on conclusion of the heating stage and a stage of returning to ambient temperature under an inert atmosphere. A composition comprising a luminophore of formula A.sub.x[BF.sub.y]:C and obtained according to the synthetic process described above, the composition being devoid of hydrogen fluoride.

A light emitting device includes a Chip Scale Packaged (CSP) LED, the CSP LED including an LED chip that generates blue excitation light; and a photoluminescence layer that covers a light emitting face of the LED chip, wherein the photoluminescence layer comprises from 75 wt % to 100 wt % of a manganese-activated fluoride photoluminescence material of the total photoluminescence material content of the layer. The device/CSP LED can further include a further photoluminescence layer that covers the first photoluminescence and that includes a photoluminescence material that generates light with a peak emission wavelength from 500 nm to 650 nm.

Provided is a wavelength conversion member that is less decreased in luminescence intensity with time by irradiation with light of an LED or LD and a light emitting device using the wavelength conversion member. A wavelength conversion member is formed of an inorganic phosphor dispersed in a glass matrix, wherein the glass matrix contains, in % by mole, 30 to 85% SiO.sub.2, 0 to 20% B.sub.2O.sub.3, 0 to 25% Al.sub.2O.sub.3, 0 to 3% Li.sub.2O, 0 to 3% Na.sub.2O, 0 to 3% K.sub.2O, 0 to 3% Li.sub.2O+Na.sub.2O+K.sub.2O, 0 to 35% MgO, 0 to 35% CaO, 0 to 35% SrO, 0 to 35% BaO, 0.1 to 45% MgO+CaO+SrO+BaO, and 0 to 4% ZnO, and the inorganic phosphor is at least one selected from the group consisting of an oxide phosphor, a nitride phosphor, an oxynitride phosphor, a chloride phosphor, an oxychloride phosphor, a halide phosphor, an aluminate phosphor, and a halophosphate phosphor.

Provided is a wavelength conversion member that is less decreased in luminescence intensity with time by irradiation with light of an LED or LD and a light emitting device using the wavelength conversion member. A wavelength conversion member is formed of an inorganic phosphor dispersed in a glass matrix, wherein the glass matrix contains, in % by mole, 30 to 85% SiO.sub.2, 0 to 20% B.sub.2O.sub.3, 0 to 25% Al.sub.2O.sub.3, 0 to 3% Li.sub.2O, 0 to 3% Na.sub.2O, 0 to 3% K.sub.2O, 0 to 3% Li.sub.2O+Na.sub.2O+K.sub.2O, 0 to 35% MgO, 0 to 35% CaO, 0 to 35% SrO, 0 to 35% BaO, 0.1 to 45% MgO+CaO+SrO+BaO, and 0 to 4% ZnO, and the inorganic phosphor is at least one selected from the group consisting of an oxide phosphor, a nitride phosphor, an oxynitride phosphor, a chloride phosphor, an oxychloride phosphor, a halide phosphor, an aluminate phosphor, and a halophosphate phosphor.

A luminescent material may have an empirical formula A.sub.1-yA′.sub.yLiXF.sub.6:Mn.sup.4+, where: A=Na, K, Rb, Cs, or combinations thereof; A′=Na, K, Rb, Li, Cs, or combinations thereof; X=Si, Ti, Hf, Zr, Sn, Pb, Ge, or combinations thereof; 0≤y<1; and A and A′ are selected differently.

Green-emitting phosphors are useful in devices including an LED light source radiationally coupled and/or optically coupled to the phosphors, which are selected from [Ba.sub.1−a−bSr.sub.aCa.sub.b].sub.x[Mg,Zn].sub.y(UO.sub.2).sub.z([P,V]O.sub.4).sub.2(x+y+z)/3, where 0≤a≤1, 0≤b≤1, 0.75≤x≤1.25, 0.75≤y≤1.25, 0.75≤z≤1.25; and [Ba,Sr,Ca,Mg,Zn].sub.p(UO.sub.2).sub.q[P,V].sub.rO.sub.(2p+2q+5r)/2, where 2.5≤p≤3.5, 1.75≤q≤2.25, 3.5≤r≤4.5.

Provided is a fluoride phosphor having higher durability. The fluoride phosphor includes a first fluoride and a second fluoride deposited on at least part of a surface of the first fluoride. The first fluoride has a composition containing an alkali metal, Si, Al, Mn, and F, wherein, when the number of moles of the alkali metal is taken as 2, the total number of moles of Si, Al, and Mn is 0.9 to 1.1; the number of moles of Al is more than 0 and less than 0.10; the number of moles of Mn is more than 0 and less than 0.20; and the number of moles of F is 5.9 to 6.1. The second fluoride has a composition which contains an alkali metal, Si, and F, and which is substantially free of Al and Mn.

A method for producing a fluoride fluorescent material comprises: preparing fluoride particles having a composition containing at least one element or ion A selected from the group consisting of alkaline metal elements and NH.sub.4.sup.+, at least one element M selected from the group consisting of Group-4 elements and Group-14 elements, Mn.sup.4+, and F, in which a molar ratio of A in 1 mol of the composition is 2, a total molar ratio of M and Mn.sup.4+ is 1, a molar ratio of Mn.sup.4+ is in a range of more than 0 and less than 0.2, and a molar ratio of F is 6; subjecting the fluoride particles to a first heat treatment at a temperature of 500° C. or more in an inert gas atmosphere; washing the first heat-treated fluoride particles with a washing liquid; and bringing the washed fluoride particles into contact with a fluorine-containing substance and subjecting the resulting fluoride particles to a second heat treatment at a temperature of 400° C. or more.