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US-12624282-B2 - Nitride phosphor, and method for producing same

US12624282B2US 12624282 B2US12624282 B2US 12624282B2US-12624282-B2

Abstract

Provided is a nitride phosphor with high emission intensity. The nitride phosphor includes: a group 1 element(s) including at least one selected from the group consisting of lithium, sodium, and potassium; a group 2 element(s) including at least one selected from the group consisting of magnesium, calcium, strontium, and barium; a group 13 element(s) including at least one selected from the group consisting of aluminum, gallium, and indium; a group 14 element(s) including at least one selected from the group consisting of silicon, germanium, and tin; nitrogen; and cerium. The nitride phosphor includes, as a host crystal, a crystal having the same crystal structure as CaAlSiN 3 , wherein the internal quantum efficiency upon excitation at 450 nm is not less than 87%.

Inventors

  • Takayuki Shinohara

Assignees

  • NICHIA CORPORATION

Dates

Publication Date
20260512
Application Date
20221018
Priority Date
20211019

Claims (11)

  1. 1 . A nitride phosphor comprising: a group 1 element(s) including at least one selected from the group consisting of lithium, sodium, and potassium; a group 2 element(s) including at least one selected from the group consisting of magnesium, calcium, strontium, and barium; a group 13 element(s) including at least one selected from the group consisting of aluminum, gallium, and indium; a group 14 element(s) including at least one selected from the group consisting of silicon, germanium, and tin; nitrogen; and cerium; the nitride phosphor comprising, as a host crystal, a crystal having the same crystal structure as CaAlSiN 3 , wherein the internal quantum efficiency upon excitation at 450 nm is not less than 87%, and wherein the nitride phosphor has a median diameter of 25 μm to 50 μm.
  2. 2 . The nitride phosphor according to claim 1 , wherein the reflectance of the nitride phosphor at a wavelength of 730 nm is not less than 89%.
  3. 3 . The nitride phosphor according to claim 1 , having a composition represented by the following formula: (Li s Na r Ca u Sr v )Al w Si x N y O k :Ce z , wherein s, t, u, v, w, x, y, z, and k satisfy 0<s<1, 0≤t≤0.03, 0<u<1, 0≤v<1, 0<w<1, 1<x<2, 2.7≤y≤3.3, 0<z≤0.1, and 0≤k≤0.3.
  4. 4 . The nitride phosphor according to claim 1 , whose composition contains aluminum, silicon, and sodium, wherein, when the total of the molar content of aluminum and the molar content of silicon in the composition is taken as 2, the molar content of sodium is more than 0 and not more than 0.03.
  5. 5 . A light-emitting device comprising: the nitride phosphor according to claim 1 ; and an excitation light source having a peak emission wavelength within the range of 350 nm to 480 nm.
  6. 6 . A method for producing the nitride phosphor according to claim 1 , comprising: providing a mixture containing: a group 1 element source containing at least one selected from the group consisting of lithium, sodium, and potassium; a group 2 element source containing at least one selected from the group consisting of magnesium, calcium, strontium, and barium; a group 13 element source containing at least one selected from the group consisting of aluminum, gallium, and indium; a group 14 element source containing at least one selected from the group consisting of silicon, germanium, and tin; and a cerium source; and subjecting the mixture to heat treatment in a sealed tungsten container, to obtain a heat-treated product; wherein at least one of the group 1 element source, the group 2 element source, the group 13 element source, and the group 14 element source contains nitrogen.
  7. 7 . The method for producing the nitride phosphor according to claim 6 , wherein the composition of the nitride phosphor comprises lithium, and the ratio of the content of lithium contained in the heat-treated product to the content of lithium contained in the mixture is not less than 75%.
  8. 8 . The method for producing the nitride phosphor according to claim 6 , wherein the heat treatment is carried out at a temperature within the range of 1300° C. to 2100° C.
  9. 9 . The method for producing the nitride phosphor according to claim 6 , wherein the heat treatment is carried out in an atmosphere containing nitrogen gas at a gauge pressure within the range of 0.1 MPa to 200 MPa.
  10. 10 . The method for producing the nitride phosphor according to claim 6 , wherein the mixture comprises a sodium source, and the content of sodium in the mixture is 0.1% by mass to 5.0% by mass.
  11. 11 . The method of producing the nitride phosphor according to claim 10 , wherein the sodium source comprises at least one selected from the group consisting of sodium amide, sodium fluoride, sodium azide, and sodium nitride.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Japanese Patent Application No. 2021-170982, filed on Oct. 19, 2021, the disclosure of which is hereby incorporated by reference in its entirety. BACKGROUND Field of the Invention The present disclosure relates to a nitride phosphor, and a method for producing the same. Description of the Related Art An increased output from a light source device is demanded in, for example, an image projection apparatus (projector) that employs a micromirror display element or the like to project light emitted from the light source device onto a screen for displaying a color image. Accordingly, the phosphor used in the light source device is required to have a high output property. For example, WO 2010/110457 describes a phosphor containing Li, Ca, Si, Al, O, N, and Ce, and including a crystal having the same crystal structure as CaAlSiN3 as a host crystal. SUMMARY A first exemplary embodiment is a nitride phosphor having a composition containing: a group 1 element(s) including at least one selected from the group consisting of lithium, sodium, and potassium; a group 2 element(s) including at least one selected from the group consisting of magnesium, calcium, strontium, and barium; a group 13 element(s) including at least one selected from the group consisting of aluminum, gallium, and indium; a group 14 element(s) including at least one selected from the group consisting of silicon, germanium, and tin; nitrogen; and cerium. The nitride phosphor includes, as a host crystal, a crystal having the same crystal structure as CaAlSiN3. The nitride phosphor shows an internal quantum efficiency of not less than 87% by excitation at 450 nm. A second exemplary embodiment is a light-emitting device including: the nitride phosphor according to the first aspect; and an excitation light source having a peak emission wavelength within the range of 350 nm to 480 nm. A third exemplary embodiment is a method of producing a nitride phosphor, the method including: providing a mixture containing: a group 1 element source containing at least one selected from the group consisting of lithium, sodium, and potassium; a group 2 element source containing at least one selected from the group consisting of magnesium, calcium, strontium, and barium; a group 13 element source containing at least one selected from the group consisting of aluminum, gallium, and indium; a group 14 element source containing at least one selected from the group consisting of silicon, germanium, and tin; and a cerium source; and subjecting the mixture to heat treatment in a sealed tungsten container, to obtain a heat-treated product. In the method of producing a nitride phosphor, at least one of the group 1 element source, the group 2 element source, the group 13 element source, and the group 14 element source constituting the mixture contains nitrogen. According to one embodiment of the present disclosure, a nitride phosphor with which high emission intensity may be obtained, and a production method therefor may be provided. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is an exemplary schematic plan view of a wavelength conversion member as seen from a main-surface side. FIG. 1B is an exemplary schematic side view of a wavelength conversion member as seen from the side-surface side, and a partial magnified image thereof. FIG. 2 is an exemplary schematic configuration diagram illustrating one example of the configuration of a light-emitting device. FIG. 3 is an exemplary schematic configuration diagram illustrating one example of the configuration of a light-emitting device. DETAILED DESCRIPTION In the present description, the term “step” includes not only an independent step, but also a step indistinguishable from another step as long as the desired purpose of the step can be achieved. Unless otherwise specified, when a plurality of substances corresponding to a certain component is present in a composition, the content of the component in the composition means the total amount of the plurality of substances present in the composition. The upper limit and lower limit of a numerical range described in the present description may be a combination of arbitrarily selected values exemplified as the numerical range. In each formula representing the composition of a phosphor in the present description, when a plurality of elements is separated by commas (,), it means that at least one of these plurality of elements is contained in the composition. In each formula representing the composition of a phosphor, a host crystal is described before a colon (:), and an activator element is described after the colon (:). In the present description, the relationship between color names and chromaticity coordinates, the relationship between light wavelength ranges and names of monochromatic lights, and the like are defined according to JIS Z8110. In the emission spectrum of a phosphor, the half-width of the phosphor means