Provided is a method of preparing photoluminescent photocatalyst beads for removing harmful substances or viruses present in air, soil, and water, and more particularly to a method of preparing photoluminescent photocatalyst beads that are efficient in decomposing and removing a mixture of hard-to-decompose organic contaminants and removing viruses by preparing a photoluminescent photocatalyst in the form of a bead, and photoluminescent photocatalyst beads obtained from the method.

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%.

[Problem] To provide a luminescent sheet having an excellent light emission performance and capable of preventing forgery.

[Solution] A luminescent sheet 1 has a first base material layer, at least one of recesses 3 and projections 4 having edges and formed on a first base material layer 2, and stress-luminescent parts each arranged at a location contacting with the edge. At least a part of the edges has a stress concentrated part where stress concentrates when stress is added to the first base material layer in a predetermined direction. The stress-luminescent part emits light having a predetermined wavelength with a light-emitting intensity depending on external load stress added to the stress concentrated part.

A light emitting device includes a light emitting element having a peak emission wavelength of 410 nm to 440nm and a phosphor member. The phosphor member includes a first phosphor having a peak emission wavelength of 430 nm to 500 nm and containing an alkaline-earth phosphate, a second phosphor having a peak emission wavelength of 440 nm to 550 nm and containing at least one of an alkaline-earth aluminate and a silicate containing Ca, Mg, and Cl, a third phosphor having a peak emission wavelength of 500 nm to 600 nm and containing a rare-earth aluminate, a fourth phosphor having a peak emission wavelength of 610 nm to 650 nm and containing a silicon nitride containing Al and at least one of Sr and Ca, and a fifth phosphor having a peak emission wavelength of 650 nm to 670 nm and containing a fluorogermanate.

Provided is a method of producing a β-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 β-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 m.sup.2/g or more.

A light emitting device includes a first light source containing a first light emitting element, and a second light source containing a second light emitting element and a second fluorescent material, the first light source emits light in a region that is demarcated in a chromaticity diagram of the CIE 1931 color coordinate system by a first straight line connecting a first point having x,y of 0.280, 0.070 in the chromaticity coordinate and a second point having x,y of 0.280, 0.500 in the chromaticity coordinate, a second straight line connecting the second point and a third point having x,y of 0.013, 0.500 in the chromaticity coordinate, a purple boundary extending from the first point toward a direction in which x decreases in the chromaticity coordinate, and a spectrum locus extending from the third point toward a direction in which y decreases in the chromaticity coordinate, in a light emission spectrum, a light emission intensity ratio I.sub.PM/I.sub.PL of a light emission intensity I.sub.PM at a wavelength of 490 nm with respect to a light emission intensity I.sub.PL at a maximum light emission peak wavelength of the first light emitting element is in a range of 0.22 or more and 0.95 or less, the second light source emits light having a color deviation duv from a blackbody radiation locus in a range of −0.02 or more and 0.02 or less measured according to JIS Z8725 with a correlated color temperature in a range of 1,500 K or more and 8,000 K or less in a chromaticity diagram of the CIE 1931 color coordinate system, and the light emitting device emits mixed color light of light emitted from the first light source and light emitted from the second light source.

Phosphors include a CaAlSiN.sub.3 family crystal phase, wherein the CaAlSiN.sub.3 family crystal phase comprises at least one element selected from the group consisting of Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Yb.

A light emitting diode package includes: a housing; a light emitting diode chip arranged in the housing; a wavelength conversion unit arranged on the light emitting diode chip; a first fluorescent substance distributed inside the wavelength conversion unit and emitting light having a peak wavelength in the cyan wavelength band; and a second fluorescent substance distributed inside the wavelength conversion unit and emitting light having a peak wavelength in the red wavelength band, wherein the peak wavelength of light emitted from the light emitting diode chip is located within a range of 415 nm to 430 nm.

A method for producing a fluorescent material is provided. The method includes preparing fluorescent material particles that contain an alkaline earth metal aluminate having a composition represented by (Sr.sub.1−x,Eu.sub.x).sub.4Al.sub.14O.sub.25, where x satisfies 0.05≦x≦0.4, and a part of Sr may be substituted by at least one element selected from the group consisting of Mg, Ca, Ba, and Zn; causing the prepared fluorescent material particles to come into contact with a liquid medium containing water; removing at least a portion of the contacted liquid medium to obtain purified fluorescent material particles; causing a phosphate compound to adhere to surfaces of the purified fluorescent material particles to obtain fluorescent material particles to which the phosphate compound is adhered; and heat treating the fluorescent material particles to which the phosphate compound is adhered at 500° C. to 700° C.

Phosphors include a CaAlSiN.sub.3 family crystal phase, wherein the CaAlSiN.sub.3 family crystal phase comprises at least one element selected from the group consisting of Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Yb.