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.

To provide a semiconductor light emitting device which is capable of accomplishing a broad color reproducibility for an entire image without losing brightness of the entire image. A light source provided on a backlight for a color image display device has a semiconductor light emitting device comprising a solid light emitting device to emit light in a blue or deep blue region or in an ultraviolet region and phosphors, in combination. The phosphors comprise a green emitting phosphor and a red emitting phosphor. The green emitting phosphor and the red emitting phosphor are ones, of which the rate of change of the emission peak intensity at 100 C. to the emission intensity at 25 C., when the wavelength of the excitation light is 400 nm or 455 nm, is at most 40%.

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: A.sub.2M.sub.(1-n)F.sub.6:Mn.sup.4+.sub.n (1), wherein 0<n0.1, 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.

Provided is a phosphor represented by the general formula: A.sub.2MF.sub.6:Mn. The elements A each represents an alkali metal element, the element M represents one or more tetravalent metallic elements selected from Si, Ge, Sn, Ti, Zr and Hf. The phosphor has a minimal light absorption rate in a wavelength range of 300 nm or more and 350 nm or less of 67% or less, and a maximum light absorption rate in a wavelength range of 400 nm or more and 500 nm or less of 65% or more. The phosphor has a Mn content of 0.3% by mass or more and 1.5% by mass or less.

A lighting apparatus is presented. The lighting apparatus includes a semiconductor light source capable of producing blue light of high power density, the semiconductor light source radiationally coupled to a phosphor of formula I in a monolithic form selected from single crystal and ceramic, Ax (M, Mn)Fy (I) where A is Li, Na, K, Rb, Cs, or a combination thereof, M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof, x is an absolute value of a charge of an [MFy] ion; and y is 5, 6, or 7.

The invention relates to a red phosphor with a narrow full width at half maximum, having improved decay time and resolving afterglow phenomenon. The fluoride-based phosphor according to the invention is characterized in including a host having a composition of the following [Formula 1] including rubidium (Rb), cesium (Cs), silicon (Si) and fluorine (F) as constituent elements, and manganese (Mn) which is solid solution treated in the host as an activator:

Rb.sub.3-xCs.sub.xSiF.sub.7 [Formula 1]

(where, 0<x<3)

A stabilized fluoride phosphor for light emitting diode (LED) applications includes a particle comprising manganese-activated potassium fluorosilicate and an inorganic coating on each of the particles. The inorganic coating comprises a silicate. A method of making a stabilized fluoride phosphor comprises forming a reaction mixture that includes particles comprising a manganese-activated potassium fluorosilicate; a reactive silicate precursor; a catalyst; a solvent; and water in an amount no greater than about 10 vol. %. The reaction mixture is agitated to suspend the particles therein. As the reactive silicate precursor undergoes hydrolysis and condensation in the reaction mixture, an inorganic coating comprising a silicate is formed on the particles. Thus, a stabilized fluoride phosphor is formed.

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/cm.sup.3 or more, and a mass median diameter (D50) of 30 m or less: general formula: A.sub.2M.sub.(1n)F.sub.6:Mn.sup.4+.sub.n (1), wherein 0<n0.1, 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.

A quantum dot having a perovskite crystal structure and including a compound represented by Chemical Formula 1:
ABX.sub.3+Chemical Formula 1
wherein, A is a Group IA metal selected from Rb, Cs, Fr, and a combination thereof, B is a Group IVA metal selected from Si, Ge, Sn, Pb, and a combination thereof, X is a halogen selected from F, Cl, Br, and I, BF.sub.4, or a combination thereof, and is greater than 0 and less than or equal to about 3; and wherein the quantum dot has a size of about 1 nanometer to about 50 nanometers.

A method includes obtaining particles of a phosphor precursor of formula A.sub.x[MF.sub.y]:Mn.sup.4+, reducing sizes of the particles of the phosphor precursor by wet milling the particles and annealing the particles that are wet milled by contacting the particles with a fluorine-containing oxidizing agent. Additionally, a manganese doped complex fluoride phosphor prepared by this method is provided. A lighting apparatus and backlight device that include manganese-doped phosphor prepared by this method also are provided.