Phosphor powder, phosphor resin composition, phosphor, light-emitting element, light-emitting device, and display device

Abstract

Provided is a phosphor powder having high absorptivity and luminous efficiency. The phosphor powder contains, in scanning electron microscope (SEM) observation, phosphor particles having a circularity of 0.6 or less at a content of 30 vol% or more, the circularity being defined by the formula: circularity = 4 πS / L2 (where S indicates the particle area and L indicates the particle perimeter).

Description

Phosphor powder, phosphor resin composition, phosphor, light-emitting element, light-emitting device, and display device

[0001] The present invention relates to a phosphor powder, a phosphor resin composition, a phosphor, a light-emitting element, a light-emitting device, and a display device.

[0002] Light-emitting devices that use light-emitting diodes (LEDs) that emit near-ultraviolet light or blue light as a light source (excitation source) and combine this with a phosphor are widely used in light-emitting devices such as lighting and backlights for mobile devices, as well as display devices such as displays.

[0003] In this light-emitting device, the phosphor absorbs the light emitted by the LED (radiated light) and emits light of a different wavelength from the absorbed light. Therefore, it is possible to obtain light of a different color tone from the LED-radiated light. For example, by combining a blue-emitting LED (blue LED) with a green phosphor and / or a red phosphor, green light, red light, or white light can be obtained.

[0004] As a document disclosing the use of phosphors for LEDs, for example, Patent Document 1 discloses a white light-emitting device that includes a light-emitting diode that emits blue light, a thiogallate-based green phosphor that emits green light, and an alkaline earth metal sulfide-based red phosphor that emits red light, and that emits white light by mixing the green light and the red light with a part of the blue light (claim 3 of Patent Document 1). The white light-emitting device is used as a backlight source for lighting, laptop computers, etc. (paragraph

[0002] of Patent Document 1).

[0005] Turning our attention to displays, another application of phosphors, mini LED displays and μ (micro) LED displays have been attracting attention in recent years as display technology has advanced. μ LED displays, in which each of the subpixels R (red), G (green), and B (blue) is composed of an independent LED, offer advantages over LCD panels, including the ability to achieve high brightness, high contrast ratio images, fast response speeds, and low power consumption. Furthermore, compared to organic EL displays, μ LED displays offer the advantage of being able to display images with high brightness and no burn-in caused by deterioration.

[0006] Development of phosphor materials (fluorescent materials) applicable to these applications is also progressing. For example, Patent Document 2 discloses a green phosphor in which an element M (wherein element M is an element such as Mn) and an element A (wherein element A is one or more metal elements other than element M and Al) are solid-solved in a host crystal having the same crystal structure as a cubic spinel-type AlON crystal (claim 1 of Patent Document 2). This green phosphor is applied to light-emitting elements such as white LEDs, and light-emitting devices using these light-emitting elements, such as lighting devices, backlight devices, image display devices, and signal devices (paragraph

[0009] of Patent Document 2).

[0007] Patent Document 3 describes a compound represented by the formula [1]: M １ ａ M ２ ｂ M ３ ｃ O ｄ (However, M １ denotes elements such as Cr, M ２ is mainly a divalent metal element, M ３ is primarily a trivalent metal element, 0.0001≦a≦0.2, 0.8≦b≦1.2, 1.6≦c≦2.4, 3.2≦d≦4.8), and contains at least two elements selected from the group consisting of Li and the like (claim 1 of Patent Document 3). This phosphor is applied to various light-emitting devices such as light-emitting sections of image display devices and lighting devices (paragraphs

[0185] and

[0186] of Patent Document 3).

[0008] Japanese Patent No. 5052507 Japanese Patent Application Laid-Open No. 2018-109076 Japanese Patent Application Laid-Open No. 2008-291203

[0009] Usually, phosphor powders are produced by pulverizing a compound synthesized by the solid-phase method. The pulverization is carried out so that the particles that make up the phosphor powder have high sphericity, because particles with high sphericity have a higher packing ability.

[0010] For example, Patent Document 2 describes that, with regard to a green phosphor, the proportion of particles having a circularity of 0.6 or more is 50% or more of the total particles on a number basis (paragraph

[0018] of Patent Document 2). Furthermore, Patent Document 3 describes that, with regard to Phosphor A, the proportion of particles having a circularity of less than 85% is usually less than 10% by number, and that the particle shape is close to spherical, so that the phosphor has appropriate dispersibility and packing density in practical use and can emit light with high brightness (paragraph

[0075] of Patent Document 3).

[0011] However, the inventors' investigations revealed that phosphor powders composed solely of particles with high sphericity are advantageous in terms of packing, but suffer from the problem of low absorptivity. Furthermore, they found that the luminous efficiency (external quantum efficiency, internal quantum efficiency) of such powders is particularly low in external quantum efficiency. The absorptivity (Abs) is the proportion of irradiated light absorbed by the phosphor. The external quantum efficiency (EQE) is the efficiency with which light irradiated by the phosphor is converted into light of a different color, and the internal quantum efficiency (IQE) is the efficiency with which the phosphor converts light absorbed by the phosphor into light of a different color.

[0012] Phosphor powders with low absorption and luminous efficiency not only have poor luminous color but also cannot efficiently convert the color of LED emitted light, resulting in low luminous intensity.

[0013] In view of these problems, the present inventors have conducted further research and have found that a phosphor powder containing a high proportion of particles with low circularity (sphericity) has high absorption and luminous efficiency.

[0014] The present invention was completed based on these findings, and aims to provide a phosphor powder having high absorptivity and luminous efficiency. Another aim of the present invention is to provide a phosphor resin composition, a phosphor, a light-emitting element, a light-emitting device, and a display device, each containing the phosphor powder.

[0015] The present invention encompasses the following aspects (1) to (12). In this specification, the expression "to" includes both the numerical values ​​of the two ends. In other words, "X to Y" is synonymous with "X or more and Y or less." Furthermore, any combination of suitable aspects can be adopted as long as technical consistency can be achieved. For example, one of the suitable numerical ranges can be combined with the other.

[0016] (1) In observation using a scanning electron microscope (SEM), the circularity is determined by the formula: circularity = 4πS / L ２ (where S is the particle area, and L is the particle circumferential length) of 0.6 or less, in a content of 30% by volume or more.

[0017] (2) In observation using a scanning electron microscope (SEM), the circularity is determined by the formula: circularity = 4πS / L ２ (where S is the particle area, and L is the particle circumferential length) of 10% by volume or more of phosphor particles having a circularity of 0.4 or less.

[0018] (3) The phosphor powder according to (1) or (2) above, which contains phosphor particles having a circularity of 0.8 or less at a content of 75% by volume or more.

[0019] (4) The phosphor powder according to any one of (1) to (3) above, wherein the cumulative 50% diameter (D50) in the volume particle size distribution is 15.0 μm or less.

[0020] (5) The phosphor powder according to any one of (1) to (4) above, wherein the cumulative 50% diameter (D50) in the volume particle size distribution is 10.0 μm or less.

[0021] (6) The phosphor powder is any one of the phosphor powders of (1) to (5) above, which contains a host crystal containing at least one metal element selected from the group consisting of barium (Ba), strontium (Sr), and calcium (Ca), gallium (Ga), and sulfur (S), and a host crystal containing at least one metal element selected from the group consisting of barium (Ba), strontium (Sr), and calcium (Ca), and sulfur (S), and a luminescent center element.

[0022] (7) A phosphor resin composition comprising the phosphor powder of any one of (1) to (6) above and a resin.

[0023] (8) A phosphor comprising the phosphor resin composition of (7) above.

[0024] (9) A light-emitting device comprising the phosphor of (8) above and an excitation source.

[0025] (10) A light-emitting device comprising the light-emitting element of (9) above.

[0026] (11) A display device comprising the light-emitting element of (9) above.

[0027] (12) The display device according to (11) above, which is a miniLED display or a μLED display.

[0028] The present invention provides a phosphor powder having high absorptivity and luminous efficiency. The present invention also provides a phosphor resin composition, a phosphor, a light-emitting element, a light-emitting device, and a display device, each containing the phosphor powder.

[0029] 1 shows SEM images of phosphor powder (Example 1) and phosphor powder (Comparative Example 1).

[0030] A specific embodiment of the present invention (hereinafter referred to as the "present embodiment") will be described. Note that the present invention is not limited to the following embodiment, and various modifications are possible within the scope of the present invention.

[0031] <<1. Phosphor Powder>> This embodiment is directed to phosphor powder. Here, powder refers to a material that is composed of multiple particles and exhibits overall fluidity in a powder state. Even if some particles are bonded or bound to each other, the material is still called a powder as long as it exhibits overall fluidity. The phosphor powder of this embodiment includes multiple phosphor particles. It can also be called an aggregate of multiple phosphor particles.

[0032] The phosphor powder of this embodiment contains a high proportion of particles with a small circularity (sphericity). When observed with a scanning electron microscope (SEM), the phosphor powder of the first aspect has a circularity of 4πS / L. ２(where S is the particle area, and L is the circumferential length of the particle) contains phosphor particles having a circularity of 0.6 or less at a content of 30% by volume or more. In other words, the content of phosphor particles having a circularity of 0.6 or less (content (circularity≦0.6)) is 30% by volume or more. The phosphor powder in the second aspect has a circularity of 0.6 or less, as determined by the formula: circularity=4πS / L when observed with a scanning electron microscope (SEM). ２ (where S is the particle area, and L is the circumferential length of the particle) phosphor particles having a circularity of 0.4 or less are contained at a content of 10% by volume or more. In other words, the content of phosphor particles having a circularity of 0.4 or less (content (circularity≦0.4)) is 10% by volume or more. Note that, hereinafter, the content of phosphor particles having a circularity of x or less will be referred to as "content (circularity≦x)."

[0033] By including a high proportion of particles with small circularity (sphericity), the absorptivity and luminous efficiency of the phosphor powder are increased. Note that circularity is an index of the circularity (sphericity) of a particle; the greater the circularity, the closer the particle shape is to a perfect sphere, and the smaller the circularity, the further the particle shape is from a perfect sphere. The circularity of a spherical particle is 1. Furthermore, SEM observation provides a two-dimensional image. Therefore, the degree of sphericity of a particle is expressed as "circularity."

[0034] The reason why the inclusion of a high proportion of particles with low circularity (sphericity), as defined in this embodiment, results in high absorptance and luminous efficiency is presumed to be as follows: Phosphor powders are typically synthesized using a solid-phase method. That is, raw material powders are fired and the resulting fired product is pulverized. The fired product is in a polycrystalline state, with multiple crystallites, which are unit crystals of the phosphor, joining together via cleavage planes (grain boundaries). When the fired product is pulverized to a desired particle size, the polycrystalline fired product is destroyed, resulting in a phosphor powder composed of multiple crystal grains.

[0035] In the pulverization process, particles are destroyed by the application of external forces. The applied external forces can be broadly divided into four types: compressive force, impact force, shear force, and friction force. Furthermore, there are two types of particle destruction during the pulverization process: surface pulverization and volume pulverization. Surface pulverization is a type of destruction in which small pieces peel off from the particle surface and gradually break down into a large number of fine particles. In contrast, volume pulverization is a type of destruction in which the entire particle breaks down into several chunks, rather than just from the particle surface, and gradually breaks down into pieces.

[0036] As mentioned above, in the past, phosphor powders were milled to increase the sphericity (roundness) of the phosphor particles in order to increase the packing density. In this method, the milling is performed by attrition, which is dominated by surface milling. Attrition is a milling method in which shear and frictional forces are applied to the particles to cause frictional milling. By finely milling and further grinding the particles, highly spherical particles can be obtained.

[0037] However, in pulverization, where grinding is the main destruction mechanism, the particle surface is strongly ground, which easily destroys the original crystal structure at the particle surface, causing significant damage to the crystal and potentially reducing the absorptivity and luminous efficiency.

[0038] In contrast, when crushing proceeds by volumetric crushing, particle destruction occurs along the cleavage planes (grain boundaries). In this mode, if crushing is performed to obtain appropriate particle sizes, non-spherical particles are obtained. Furthermore, because the particles are destroyed along the cleavage planes, the original crystal structure is more likely to be maintained, and damage to the crystal is minimal. This is thought to result in higher absorptivity and luminous efficiency of the resulting phosphor powder.

[0039] Thus, the phosphor powder of this embodiment, which is composed of particles with low sphericality, is thought to cause less damage to the crystals than conventional phosphor powder, which is composed of particles with high sphericality, and therefore has higher absorption rate and luminous efficiency.

[0040] The phosphor powder of this embodiment is characterized by high absorptivity and luminous efficiency due to a high proportion of particles with low circularity (sphericity), i.e., a high content (circularity ≦0.6) or a high content (circularity ≦0.4). In particular, the phosphor powder of the second embodiment, in which the content (circularity ≦0.4) is limited to 10% by volume or more, contains even a small amount (10% by volume or more) of particles with particularly low circularity, and is therefore considered to have high luminous efficiency. Furthermore, the phosphor powder of the first embodiment, in which the content (circularity ≦0.6) is limited to 30% by volume or more, contains a significant amount (30% by volume or more) of particles with moderately low circularity. Therefore, it is considered that the same effect (high luminous efficiency) as the second embodiment can be obtained. From the viewpoint of increasing absorptivity and luminous efficiency, the higher the content (circularity ≦0.6) or the content (circularity ≦0.4), the more preferable.

[0041] In the first aspect, the content (circularity ≦0.6) is preferably 40 vol% or more, more preferably 50 vol% or more, even more preferably 60 vol% or more, and particularly preferably 70 vol% or more. On the other hand, phosphor powder with an excessively high content (circularity ≦0.6) may result in increased manufacturing costs. The content (circularity ≦0.6) is typically 90 vol% or less, or 80 vol% or less. The content (circularity ≦0.6) is preferably 30 vol% or more and 90 vol% or less, more preferably 40 vol% or more and 90 vol% or less, even more preferably 50 vol% or more and 90 vol% or less, particularly preferably 60 vol% or more and 80 vol% or less, and most preferably 70 vol% or more and 80 vol% or less.

[0042] In the second aspect, the content (circularity ≦0.4) is preferably 20 vol% or more, more preferably 30 vol% or more, even more preferably 40 vol% or more, and particularly preferably 50 vol% or more. On the other hand, phosphor powder with an excessively high content (circularity ≦0.4) may result in increased manufacturing costs. The content (circularity ≦0.4) is typically 70 vol% or less, or 60 vol% or less. The content (circularity ≦0.4) is preferably 10 vol% or more and 70 vol% or less, more preferably 20 vol% or more and 70 vol% or less, even more preferably 30 vol% or more and 70 vol% or less, particularly preferably 40 vol% or more and 60 vol% or less, and most preferably 50 vol% or more and 60 vol% or less.

[0043] In the first embodiment, as in the second embodiment, a higher content (circularity ≦0.4) is desirable. The content (circularity ≦0.4) is preferably 10% by volume or more and 70% by volume or less, more preferably 20% by volume or more and 70% by volume or less, even more preferably 30% by volume or more and 70% by volume or less, particularly preferably 40% by volume or more and 60% by volume or less, and most preferably 50% by volume or more and 60% by volume or less.

[0044] In the second embodiment, similarly to the first embodiment, a higher content (circularity ≦ 0.6) is desirable. The content (circularity ≦ 0.6) is preferably 30 vol% to 90 vol%, more preferably 40 vol% to 90 vol%, even more preferably 50 vol% to 90 vol%, particularly preferably 60 vol% to 80 vol%, and most preferably 70 vol% to 80 vol%.

[0045] In either the first or second aspect, the phosphor powder of this embodiment preferably contains phosphor particles having a circularity of 0.8 or less at a content of 75% by volume or more. In other words, the content of phosphor particles having a circularity of 0.8 or less (content (circularity ≦ 0.8)) is 75% by volume or more. It can also be said that the content of particles having a circularity of more than 0.8 (content (circularity > 0.8)) is less than 25% by volume. Since the proportion of spherical particles is reduced, it is possible to further increase the absorption rate and luminous efficiency. The content (circularity ≦ 0.8) is more preferably 85% by volume or more, and even more preferably 95% by volume or more. The content (circularity ≦ 0.8) is typically 100% by volume or less.

[0046] The content (circularity≦x) (where x=0.1 to 1.0) can be determined by observing the phosphor powder with a scanning electron microscope (SEM). Specifically, the phosphor powder is spread thinly so that the particles contained therein do not overlap as much as possible. In this state, SEM observation is performed at a magnification of approximately 3,000 to 50,000 times to obtain an SEM observation image. The obtained SEM observation image is then subjected to binarization processing using image analysis to determine the outer shape of each particle, and the perimeter (L) and particle area (S) of each particle are further determined. Since the SEM observation image provides a projected cross-sectional image of the particle represented two-dimensionally, the perimeter and particle area in this projected cross-sectional image can be obtained. Next, the obtained perimeter (L) and particle area (S) are used to determine the circularity of each particle according to the following formula (1).

[0047]

[0048] The volume of the particle whose circularity has been determined is calculated from the volume of an equivalent sphere. Specifically, the radius (r) of a perfect circle having the same area as the particle area (S) is calculated from the particle area. The volume (V) of a perfect sphere having this radius (r) is then calculated using the formula: V = 4 / 3πr ３ It is calculated by:

[0049] The same procedure is performed for multiple particles in multiple fields of view to obtain the relationship between particle circularity and particle volume. Based on this relationship, a frequency distribution graph is then obtained, with particle circularity on the horizontal axis and particle volume (V) on the vertical axis. A cumulative frequency distribution graph is also obtained, with circularity on the horizontal axis and cumulative volume, calculated by integrating particle volumes from smallest to largest, on the vertical axis. In the frequency distribution graph and cumulative frequency distribution graph, the vertical axis is normalized so that the total particle volume (V) is 100% by volume. In the normalized cumulative frequency distribution graph, the cumulative volume of particles with a circularity of x or less is determined as the content (circularity≦x). For example, the content of particles with a circularity of 0.6 or less is determined as the content (circularity≦0.6).

[0050] According to one aspect, the phosphor powder of this embodiment preferably has a cumulative 50% diameter (D50) in the volume particle size distribution of 15.0 μm or less. By appropriately reducing D50, the absorptivity of the phosphor powder increases. D50 is preferably 14.0 μm or less, more preferably 13.0 μm or less. On the other hand, if D50 is excessively small, the internal quantum efficiency may decrease. D50 is preferably 5 μm or more, more preferably 7 μm or more. Phosphor powders having such particle sizes are particularly suitable for, but not limited to, mini LED displays. Note that D50 is determined by calculating a cumulative distribution curve based on the volume (mass) of the phosphor powder, and then taking the 50% diameter of this cumulative distribution curve. The method for measuring D50 will be described later.

[0051] According to another aspect, the phosphor powder of this embodiment preferably has a cumulative 50% diameter (D50) in the volume particle size distribution of 10.0 μm or less. By appropriately reducing D50, the absorptivity of the phosphor powder increases. D50 is preferably 9 μm or less, more preferably 8 μm or less, and even more preferably 7 μm or less. On the other hand, if D50 is excessively small, the internal quantum efficiency may decrease. D50 is preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 2 μm or more. Phosphor powders having such particle sizes are particularly suitable for, but not limited to, μLED display applications.

[0052] The phosphor powder of this embodiment is not limited in its material composition as long as it exhibits fluorescence. Fluorescent materials are often composed of a host crystal and a luminescent center (activator), with the luminescent center being dissolved in an appropriate host crystal at a concentration of several mol %. Known fluorescent materials include oxide-based, sulfide-based, oxysulfide-based, nitride-based, and oxynitride-based materials, and any of these may be used.

[0053] For example, oxide-based fluorescent materials (Y, Gd, Lu) ３ (Al, Ga) ５ O １２ : Ce ３＋ , (Ba, Sr, Ca) ２ SiO ４ :Eu ２＋ , (Ba, Sr, Ca) ３ MgSi２ O ８ : Eu ２＋ 、CaAl １２ O １９ : Mn ４＋ 、Ca ３ Sc ２ Si ３ O １２ : Ce ３＋ 、CaSc ２ O ４ : Ce ３＋ 、(Ba, Sr) ３ SiO ５ : Eu ２＋ 、Li ２ SrSiO ４ : Eu ２＋ 、Ba ９ Sc ２ Si ６ O ２４ : Eu ２＋ 、Ca ３ Si[[ID=�2]] ２ O ７ : Eu ２＋ 、LiSrPO ４ : Eu ２＋ 、CaLa ４ Si ３ O １３ : Eu ３＋ 、Ba ２ Gd ３ Li ３ Mo ８ O ３２ : Eu ３＋ and BaMgAl １０ O １７ : Eu ２＋ ,Mn ２＋ etc. can be mentioned.

[0054] As sulfide-based fluorescent materials, (Ba, Sr, Ca)Ga ２ S ４ : Eu ２＋ 、(Ba, Sr, Ca)Ga ２ S ４ : Ce ３＋ 、(Sr, Ca)S: Eu ２＋ 、(Sr, Cd)S: Eu<c ２＋ and ZnS: Cu etc. can be mentioned.

[0055] As oxysulfide-based fluorescent materials, (La, Y) ２ O２ S: EU ３＋ , La(Ca,Sr)Ga ３ S ６ O:Eu ２＋ and La ２ O ３ S: EU ３＋ Examples include:

[0056] Nitride-based fluorescent materials (Ba, Sr, Ca) ２ Si ５ N ８ :Eu ２＋ , (Ba,Ca,Sr)AlSiN ３ :Eu ２＋ , La ３ Si ６ N １１ : Ce ３＋ , (Ba,Sr,Ca)LiAl ３ N ４ :Eu ２＋ , Sr(Mg ３ SiN ４ ): Eu ２＋ and (Ba, Sr) ２ Si ５ N ８ :Eu ２＋ Examples include:

[0057] As oxynitride fluorescent materials, Eu-containing α-type sialon, Eu-containing β-type sialon, Ba ９ Sc ３ Si ６ O ２１ N ３ :Eu ２＋ , Ba ３ Si ６ O １２ N ２ :Eu ２＋ ,BaSi ２ O ２ N ２ :Eu ２＋ and (Ba, Sr, Ca)AlSi(ON) ３ :Eu ２＋ Examples include:

[0058] Other fluorescent materials include Sr １０ (P.O. ４ ) ６ C １２ :Eu２＋ and K. ２ (Si,Ge,Ti)F ６ : Mn ４＋ Examples include:

[0059] Preferably, the phosphor powder contains, as in the compositions listed as the sulfide phosphor material described above, either a host crystal containing at least one metal element selected from the group consisting of barium (Ba), strontium (Sr), and calcium (Ca), gallium (Ga), and sulfur (S), or a host crystal containing at least one metal element selected from the group consisting of barium (Ba), strontium (Sr), and calcium (Ca), and sulfur (S), and a luminescent center element.

[0060] When the phosphor powder contains a host crystal containing a metal element selected from Ba, Sr, and Ca, Ga, and S, and a luminescent center element, it is preferable that the luminescent center contains at least one element selected from the group consisting of europium (Eu), cerium (Ce), manganese (Mn), and samarium (Sm). From the viewpoint of further increasing the internal quantum efficiency upon excitation by blue light emitted from an LED, it is preferable that the luminescent center contains Eu, and a divalent ion of Eu (Eu ２＋ ), and more preferably, Eu ２＋ More preferably, the phosphor powder contains only a compound represented by the general formula: MGa ２ S ４ :Eu ２＋ (wherein M is at least one element selected from the group consisting of Ba, Sr, and Ca). A phosphor powder having such a composition emits green light when excited by excitation light having a wavelength in the near-ultraviolet to blue region (approximately 300 nm to 510 nm).

[0061] When the phosphor powder contains a host crystal containing a metal element selected from Ba, Sr, and Ca and S, and a luminescent center element, it is preferable that the luminescent center contains at least one element selected from the group consisting of europium (Eu), cerium (Ce), manganese (Mn), and samarium (Sm). More preferably, the phosphor powder is represented by the general formula: MS:Eu ２＋(wherein M is at least one element selected from the group consisting of Ba, Sr, and Ca). A phosphor powder having such a composition emits red light when excited by light with a wavelength in the ultraviolet to visible light range (approximately 250 nm to 610 nm).

[0062] Regarding the ratio of the luminescent centers in the phosphor powder, from the viewpoint of further improving the luminescence intensity, the ratio (XA / (XM+XA)) of the molar amount XA of the luminescent center element A to the sum (XM+XA) of the molar amount XM of the alkaline earth metal element M contained in the phosphor powder and the molar amount XA of the luminescent center element A is preferably 0.05 or more, more preferably 0.07 or more, and even more preferably 0.10 or more. Furthermore, from the viewpoint of preventing concentration quenching, XA / (XM+XA) is preferably 0.30 or less, more preferably 0.25 or less, and even more preferably 0.20 or less.

[0063] According to a particularly preferred embodiment, the phosphor powder is (Ba ｘ Sr １－ｘ－ｙ Ca ｙ ) １－ｚ Ga ｔ S ４－δ :Eu ｚ (where 0≦x≦0.5, 0≦y≦0.5, 0.01≦z≦0.3, 1.5≦t≦2.5, and δ is a positive integer that satisfies the charge neutrality condition.) It is more preferable that x, y, z, and t satisfy the relationships 0≦x≦0.4, 0≦y≦0.4, 0.05≦z≦0.20, and 1.8≦t≦2.2.

[0064] The phosphor powder may or may not have a surface coating layer. However, providing a coating layer can improve durability such as moisture resistance. From the viewpoint of improving durability while maintaining the good luminescence properties of the phosphor, the coating layer is preferably made of silicon dioxide (SiO ２ ), zinc oxide (ZnO), aluminum oxide (Al ２ O ３ ), titanium oxide (TiO ２ ), and / or oxides containing boron (B), barium sulfate (BaSO ４ It is preferable that the inorganic compound is composed of one or more inorganic compounds such as metal sulfates.

[0065] <<2. Manufacturing Method of Phosphor Powder>> The manufacturing method of the phosphor powder of this embodiment is not limited as long as it satisfies the above-mentioned requirements. Preferably, the phosphor powder is prepared by synthesizing a coarse phosphor powder from raw materials and then subjecting this coarse phosphor powder to particle size adjustment processing such as pulverization and classification. An example of a suitable manufacturing method of the phosphor powder is described below.

[0066] First, a raw material mixture is obtained by weighing and mixing at least one of a strontium (Sr) raw material, a barium (Ba) raw material, and a calcium (Ca) raw material, a gallium (Ga) raw material, a sulfur (S) raw material, and a europium (Eu) raw material. As the strontium (Sr) raw material, the barium (Ba) raw material, and the calcium (Ca) raw material, an oxide, a double oxide, and / or a carbonate of each element can be used. As the gallium (Ga) raw material, an oxide (Ga ２ O ３ As the sulfur (S) raw material, strontium sulfide (SrS), barium sulfide (BaS), calcium sulfide (CaS), sulfur (S), silicon sulfide (SiS) can be used. ２ ), cerium sulfide (Ce ２ S ３ ), hydrogen sulfide (H ２ As a source of europium (Eu), europium fluoride (EuF ３ ), europium oxide (Eu ２ O ３ ), europium chloride (EuCl ３ ) and other europium compounds can be used.

[0067] In order to adjust the wavelength of the phosphor powder and improve the luminous efficiency, rare earth elements such as praseodymium (Pr) and samarium (Sm) may be added to the raw materials. Furthermore, in order to improve the excitation efficiency, at least one element selected from rare earth elements such as scandium (Sc), lanthanum (La), gadolinium (Gd), and lutetium (Lu) may be added to the raw materials as a sensitizer. However, it is preferable that the amount of each of these elements added is 5 mol % or less relative to strontium (Sr). By keeping the content of these elements at 5 mol % or less, it becomes easier to prevent a large amount of heterophase from precipitating, which would otherwise cause a decrease in brightness. Furthermore, alkali metal elements and silver ions (Ag ＋ Monovalent cationic metals such as Cr, Ni, and the like, and halogen ions such as chlorine (Cl), fluorine (F), and iodine (I) may be added to the raw materials as charge compensators. From the viewpoint of charge compensation effect and brightness, the amount of the added material is preferably approximately equal to the content of the aluminum group or rare earth element.

[0068] The method for mixing the raw materials is not limited. Either a dry method or a wet method may be used. In the case of dry mixing, for example, zirconia balls are used as media and the raw material mixture is mixed in a mixer such as a paint shaker or a ball mill, and dried as necessary. In the case of wet mixing, a solvent such as water is added to the raw materials to form a suspension, and the mixture is mixed in a mixer such as a paint shaker or a ball mill using zirconia balls as media. The media is then separated using a sieve or the like, and the solvent is removed from the suspension by a drying method such as reduced pressure drying or vacuum drying.

[0069] The resulting raw material mixture is then fired to produce a fired product. Before firing, the raw material mixture may or may not be subjected to pulverization, classification, and / or drying, as necessary.

[0070] Firing is preferably carried out at a temperature of 1000°C or higher. At 1000°C or higher, sufficient and uniform firing can be achieved. The upper limit of the firing temperature cannot be determined in general because it is determined by the endurance temperature of the firing furnace and the production temperature. However, firing at a temperature of 1000°C or higher and 1200°C or lower is preferred. The firing time is determined in relation to the firing temperature. However, a temperature of 2 hours or higher and 24 hours or lower is preferred.

[0071] The firing atmosphere may be an inert gas or a reducing gas, etc. Examples include an argon atmosphere, a nitrogen atmosphere, a sulfur atmosphere, an argon atmosphere containing hydrogen gas, a nitrogen atmosphere containing hydrogen gas, a hydrogen sulfide atmosphere, etc. Among these, firing in a hydrogen sulfide atmosphere is preferred.

[0072] When the raw material mixture contains a sulfur (S) raw material, it can be calcined under an atmosphere of hydrogen sulfide, carbon disulfide, or an inert gas. When hydrogen sulfide or carbon disulfide is used, these become sulfur compounds during calcination, which have the effect of suppressing decomposition of the product. On the other hand, when the raw material does not contain a sulfur raw material, it is preferable to calcinate under a sulfur-containing atmosphere such as hydrogen sulfide or carbon disulfide.

[0073] The fired product is then pulverized (disintegrated) to produce a phosphor powder. The pulverization can be performed using a known pulverizer such as a ball mill, stamp mill, jet mill, crusher, and / or paint shaker. If necessary, the pulverized product can be classified. The classification can be performed using a known method such as a sieve or an air classifier.

[0074] In the manufacturing method of this embodiment, pulverization is performed so that the resulting phosphor powder contains a high proportion of particles with low circularity. Specifically, pulverization is performed using a technique that allows sufficient volumetric crushing rather than attrition. Particle destruction occurs along cleavage planes (grain boundaries), resulting in minimal damage to the crystals. This allows for the production of phosphor powder with high absorptivity and luminous efficiency.

[0075] In order to prioritize pulverization by crushing, the pulverization method and pulverization conditions are adjusted. Taking the case of pulverization using a stamp mill as an example, the fired material is pulverized by the stamp mill for a predetermined time to a degree that does not result in excessive pulverization, and then sieved for a predetermined time. If the fired material remains on the sieve, pulverization by the stamp mill and sieving may be performed again for a predetermined time as necessary. Next, the fired material that falls below the sieve may be similarly pulverized by the stamp mill and sieved repeatedly as necessary. In this way, a fired material with a predetermined circularity can be obtained.

[0076] <<3. Phosphor Resin Composition>> The phosphor resin composition of this embodiment contains the above-described phosphor powder and a resin. The phosphor resin composition is a phosphor paste that is a precursor of a phosphor. The phosphor is produced by applying or molding the phosphor resin composition.

[0077] The resin may be, for example, one or more selected from thermoplastic resins, thermosetting resins, ionizing radiation curable resins, and two-component curable resins. Examples of thermoplastic resins include polyolefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate resins; polyacrylic acid resins such as polyacrylic acid or its esters, polymethacrylic acid or its esters; polyvinyl resins such as polystyrene and polyvinyl chloride; cellulose resins such as triacetyl cellulose; and urethane resins such as polyurethane. Examples of thermosetting resins include silicone resins, phenolic resins, epoxy resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, polyurethane resins, and polyimide resins. Examples of ionizing radiation curable resins include acrylic resins, urethane resins, vinyl ester resins, and polyester alkyd resins. These resins may be used not only as polymers but also as oligomers or monomers. Examples of two-component curable resins include epoxy resins.

[0078] The amount of phosphor powder contained in the phosphor resin composition is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, per 100 parts by mass of resin, from the viewpoint of easily ensuring absorptivity while obtaining sufficient external quantum efficiency, while being 100 parts by mass or less, more preferably 70 parts by mass or less, per 100 parts by mass of resin, from the viewpoint of ensuring favorable moldability (fillability).

[0079] The phosphor resin composition may contain an organic solvent, an additive, and the like. The viscosity of the phosphor resin composition (phosphor paste) can be adjusted by adding an organic solvent. Any known organic solvent that dissolves resins may be used. As the additive, an inorganic filler such as glass particles or metal oxide particles, or a flow adjuster made of an organic component may be used.

[0080] The phosphor resin composition is produced by mixing and kneading a phosphor powder, a resin, and, if necessary, an organic solvent and additives. The mixing and kneading may be performed using known means, such as a triple roll mill, a kneader, a single- or double-screw kneader, a revolution-type stirring and degassing device, and / or a planetary mill. The resulting phosphor resin composition is used as a phosphor paste for producing a phosphor.

[0081] <<4. Phosphor>> The phosphor of this embodiment is made of the phosphor resin composition described above. In other words, it is a molded body of the phosphor resin composition. The term "molded body" conceptually includes coatings and fillers obtained from the composition. The phosphor resin composition (phosphor paste) is applied, filled, or molded, and then dried and / or cured as necessary to produce the phosphor. The phosphor has phosphor powder (particles) dispersed in a resin matrix.

[0082] <<5. Light-Emitting Element>> The light-emitting element of this embodiment includes the above-described phosphor and an excitation source. The excitation source emits light toward the phosphor to excite it. An LED with a central wavelength of 250 nm or more and 510 nm or less, particularly a blue LED with a central wavelength of 450 nm or more and 460 nm or less, is suitable as the excitation source. The arrangement of the phosphor and excitation source is not limited as long as light from the excitation source is incident on the phosphor. However, it is preferable to arrange the phosphor directly above the excitation source. This allows the phosphor to more efficiently absorb the light emitted from the excitation source and perform color conversion. For example, when the light-emitting element is applied to a μLED display, it is preferable to arrange the LED as the excitation source below and the phosphor above it within each package rib of the display. While quantum dots can also be used as components of a light-emitting element instead of phosphors, quantum dots often contain environmentally restricted substances. Furthermore, due to their poor durability, phosphors are more advantageous.

[0083] <<6. Light-Emitting Device>> The light-emitting device of this embodiment includes the above-described light-emitting element. The light-emitting device is not particularly limited as long as it includes a fluorescent light-emitting element. Examples of such devices include a lighting device, a backlight device, and a signal device.

[0084] <<7. Display Device>> The display device of this embodiment includes the above-described light-emitting element. There are no particular limitations on the display device as long as it includes a phosphor light-emitting element. The display device of this embodiment includes a phosphor that has high absorption and high luminous efficiency, and is therefore characterized by high luminous intensity and excellent luminous color. The display device of this embodiment is particularly preferably a miniLED display or a μLED display.

[0085] The present invention will be described in more detail using the following examples, but the present invention is not limited to the following examples.

[0086] (1) Preparation of Phosphor Powder and Phosphor [Example 1] Barium sulfide (BaS), strontium sulfide (SrS), europium sulfide (EuS), and gallium sulfide (Ga ２ S ３ ) were prepared and weighed out so that the molar ratios were Ba 0.22, Sr 0.65, Eu 0.13, and Ga 2.00. The weighed materials were then mixed for 100 minutes using a paint shaker with zirconia balls having a diameter of 3 mm to obtain a raw material composition. The raw material composition was then mixed with hydrogen sulfide (H ２ S) atmosphere at a temperature increase rate of 5°C / min, a firing temperature of 1100°C, and a firing time of 6 hours to obtain a fired product.

[0087] 100 g of the resulting fired material was pulverized in a stamp mill for 10 minutes and then sieved using a sieve with a mesh size of 250 μm for 30 minutes. The pulverized material on the sieve was repeatedly subjected to stamp mill processing and sieving until no pulverized material remained. The resulting pulverized material that remained below the sieve was then pulverized again in a stamp mill for 10 minutes and then sieved using a sieve with a mesh size of 53 μm for 30 minutes. The pulverized material that remained above the sieve was then repeatedly subjected to stamp mill processing and sieving until no pulverized material remained. The resulting pulverized material that remained below the sieve was then pulverized again in a stamp mill for 10 minutes and then sieved using a sieve with a mesh size of 25 μm for 30 minutes. The pulverized material that remained above the sieve was then repeatedly subjected to stamp mill processing and sieving until no pulverized material remained. The pulverized material that remained below the sieve was then recovered to obtain a phosphor powder. The composition of the resulting phosphor powder is shown in Table 1 below.

[0088] Example 2 A phosphor powder was obtained in the same manner as in Example 1, except that the stamp milling time was changed to 15 minutes in all cases. The composition of the obtained phosphor powder is shown in Table 1 below.

[0089] [Example 3] A fired product was obtained using the same procedure as in Example 1. Next, 100 g of the obtained fired product was pulverized in a stamp mill for 15 minutes, and then sieved using a sieve with a mesh size of 250 μm for 30 minutes. The pulverized product on the sieve was subjected to the stamp mill treatment and sieving operations repeatedly until no particles remained on the sieve. Thereafter, the obtained pulverized product that fell below the sieve was again pulverized in a stamp mill for 15 minutes, and then sieved using a sieve with a mesh size of 106 μm for 30 minutes. The pulverized product that fell above the sieve was subjected to the stamp mill treatment and sieving operations repeatedly until no particles remained on the sieve. Thereafter, the obtained pulverized product that fell below the sieve was further pulverized in a stamp mill for 15 minutes, and then sieved using a sieve with a mesh size of 25 μm for 30 minutes. The pulverized product that fell above the sieve was subjected to the stamp mill treatment and sieving operations repeatedly until no particles remained on the sieve. The crushed material that did not pass through the sieve was collected to obtain a phosphor powder, the composition of which is shown in Table 1 below.

[0090] Example 4 Strontium sulfide (SrS), calcium sulfide (CaS), europium sulfide (EuS), and gallium sulfide (Ga ２ S ３) was prepared, and the raw materials were weighed so as to obtain a phosphor powder having the composition shown in Table 1 below. Otherwise, the same procedure as in Example 1 was carried out to obtain a phosphor powder.

[0091] Example 5 Strontium sulfide (SrS), europium sulfide (EuS), and gallium sulfide (Ga ２ S ３ ) was prepared, and the raw materials were weighed so as to obtain a phosphor powder having the composition shown in Table 1 below. Otherwise, the same procedure as in Example 1 was carried out to obtain a phosphor powder.

[0092] Comparative Example 1 A fired product was obtained in the same manner as in Example 1. The fired product was then crushed and pulverized using a jet mill (Dec Group, MC DecJet (registered trademark) 30) to obtain a phosphor powder. The gas pressure was 0.1 MPa, and the supplied gas was nitrogen (N ２ The composition of the obtained phosphor powder is shown in Table 1 below.

[0093] (2) Evaluation The phosphor powders and phosphors obtained in Examples 1 to 5 and Comparative Example 1 were evaluated for various properties in the following manner.

[0094] <Circularity> The circularity and content of the phosphor powder were determined by SEM observation. Specifically, the phosphor powder was dispersed on carbon tape using a disperser (Thermo Scientific, NEBULA) at a vacuum of 0.8 to 0.9 bar, so that the particles contained therein did not overlap as much as possible. This was observed using an SEM (Thermo Scientific, Phenom XL G2). The observation was performed at a magnification of 10,000 times and an accelerating voltage of 10.0 kV, and a backscattered electron image was obtained.

[0095] The obtained backscattered electron image was binarized using image processing software (Phenom SmartScan, Thermo Scientific) under the following conditions: Min: 132, Max: 140, and Gamma: 54 for histogram adjustment.

[0096] From the obtained binarized image, the particle shape was determined using the ParticleMetric function of image analysis software (Thermo Scientific, Particle ProSuite), and the perimeter (L) and particle area (S) of each particle were determined. Particle detection in image analysis was performed under the following conditions: Min contrast 0.90, Merge shared borders 0.70, Ignore covered particles disabled, Exclude edge particles enabled, Conductance 0.30, Min detection size 0.10%. Next, using the obtained perimeter (L) and particle area (S), the circularity of each particle was calculated according to the following formula (1).

[0097]

[0098] The volume of the particle whose circularity was determined was calculated from the volume of an equivalent sphere. Specifically, the radius (r) of a perfect circle having the same area as the particle area (S) was calculated from the particle area. The volume (V) of a perfect sphere having this radius (r) was calculated using the formula: V = 4 / 3πr ３ This was determined as the particle volume (V).

[0099] The same procedure was performed in multiple fields of view so that 2,000 or more particles could be confirmed, and the relationship between particle circularity and particle volume was obtained. Based on this relationship, a frequency distribution graph was obtained with particle circularity on the horizontal axis and particle volume (V) on the vertical axis. A cumulative frequency distribution graph was also obtained with circularity on the horizontal axis and cumulative volume, calculated by integrating particle volumes from the smallest to the largest, on the vertical axis. In the frequency distribution graph and cumulative frequency distribution graph, the vertical axis was normalized so that the total particle volume (V) was 100% by volume. In the normalized cumulative frequency distribution graph, the cumulative volume of particles with a circularity of x or less was calculated as the content (circularity≦x) (x=0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0).

[0100] <Particle Size Distribution> The particle size distribution of the phosphor powder was measured using a laser diffraction particle size distribution analyzer (Microtrac Bell, MT3300EXII). First, the circulation system of the device was filled with a 99.5% ethanol solution, and the sample (phosphor powder) was added so that the transmittance was 95-60%. Before addition, the sample was subjected to a dispersion treatment such as ultrasonic dispersion (40 W, 180 seconds). Next, the particle size was measured while circulating the particles in the solvent in the measurement cell. From the measurements, a volumetric frequency particle size distribution curve and a cumulative particle size distribution curve were obtained, and the cumulative 50% diameter (D50) was calculated from these. The particle size measurement was performed under the following conditions.

[0101] - Flow rate: 80% - Ultrasonic: 40W, 180 seconds - Set Zero time: 10 seconds - Measurement time: 30 seconds - Number of measurements: 1 - Transmittance: Transmitted - Particle refractive index: 2.46 - Particle shape: Aspherical - Solvent refractive index: 1.36

[0102] <Absorptivity and Luminous Efficiency> The absorptivity and luminous efficiency (external quantum efficiency, internal quantum efficiency) of the phosphor powders obtained in Examples 1 to 5 and Comparative Example 1 were measured. Specifically, a spectrofluorometer FP-8500 and an integrating sphere unit ISF-834 (manufactured by JASCO Corporation) were used, and measurements were performed in accordance with a solid-state quantum efficiency calculation program. The spectrofluorometer was calibrated using a secondary standard light source and rhodamine B. The formulas for calculating the absorptivity, internal quantum efficiency, and external quantum efficiency of the phosphor when the excitation light is 450 nm are shown below. These formulas comply with the description in the instruction manual for the solid-state quantum efficiency calculation program FWSQ-6-17(32) manufactured by JASCO Corporation.

[0103] P １ (λ) is the standard white board spectrum, and P ２ (λ) is the sample spectrum, and P ３ Let (λ) be the indirectly excited sample spectrum. １ (λ) is the area L surrounded by the excitation wavelength range of 461 nm to 481 nm １ (See the following formula (i)) is the excitation intensity. ２ (λ) is the area L surrounded by the excitation wavelength range of 461 nm to 481 nm ２(see formula (ii) below) is the sample scattering intensity. ２ (λ) is the area E surrounded by the excitation wavelength range of 482 nm to 648.5 nm ２ (See the following formula (iii)) is the fluorescence intensity of the sample. ３ (λ) is the area L surrounded by the excitation wavelength range of 461 nm to 481 nm ３ (See the following formula (iv)) is the indirect scattering intensity. ３ (λ) is the area E surrounded by the excitation wavelength range of 482 nm to 648.5 nm ３ (see formula (v) below) is defined as the indirect fluorescence intensity.

[0104]

[0105] The absorptance (Abs) is the ratio of the excitation light attenuated by the sample to the incident light, as shown in the following formula (vi): The external quantum efficiency (EQE) is the ratio of the number of fluorescent photons N emitted from the sample to the excitation light attenuated by the sample, as shown in the following formula (vii): ｅｍ is the number of photons of the excitation light irradiated on the sample, N ｅｘ The internal quantum efficiency (IQE) is calculated by dividing the number of photons of fluorescence emitted from the sample, N, by the following formula (viii): ｅｍ is the number of photons of the excitation light absorbed by the sample, N ａｂｓ The value is obtained by dividing by .

[0106]

[0107] (3) Evaluation Results The evaluation results for the phosphor powders of Examples 1 to 5 and Comparative Example 1 are summarized in Table 1 below. In Table 1 below, the content value for a circularity of ≦0.1 represents the cumulative volume frequency of phosphor particles having a circularity of 0 or more and 0.1 or less. Similarly, the content value for a circularity of ≦0.2 represents the cumulative volume frequency of phosphor particles having a circularity of 0 or more and 0.2 or less. The same applies to circularities up to 1.0.

[0108] As can be seen from Table 1 below, the greater the cumulative volume frequency (content) of particles with low circularity, the higher the absorptivity (Abs) and luminous efficiency such as external quantum efficiency (EQE). In particular, the effect of the content of phosphor particles with a circularity of 0.6 or less (content (circularity ≦ 0.6)) is significant, and the higher the content (circularity ≦ 0.6)), the higher the absorptivity and luminous efficiency.

[0109] Considering the frequency distribution and cumulative frequency distribution of circularity of the phosphor powders of Examples 1 to 5 and Comparative Example 1 from Table 1, the phosphor powders of Examples 1 to 5 have a relatively large proportion of particles with low circularity. For example, Example 1 has a high frequency of particles with a circularity of 0.2 to 0.3, and Examples 2 and 3 have a high frequency of particles with a circularity of 0.4 to 0.5. In contrast, the phosphor powder of Comparative Example 1 has a large proportion of particles with a high circularity. That is, the frequency of particles with a circularity of 0 to 0.6 is relatively low, and instead the frequency of particles with a circularity of 0.6 to 0.7 is the highest. The frequency of particles with a circularity of 0.8 to 0.9 is also relatively high.

[0110]

[0111] SEM images of the phosphor powder of Example 1 and the phosphor powder of Comparative Example 1 are shown in Figures 1 and 2, respectively. The particles constituting the phosphor powder of Example 1 have low circularity (sphericity) and irregular shapes (Figure 1). In contrast, the particles constituting the phosphor powder of Comparative Example 1 have high circularity (sphericity) (Figure 2).

[0112] From the above results, it can be seen that this embodiment provides a phosphor powder with high absorptivity and luminous efficiency.

Claims

1. A host crystal comprising at least one metal element selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca), gallium (Ga) and sulfur (S), and a host crystal comprising at least one metal element selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca) and sulfur (S), and europium (Eu) as a luminescent center element; In observation using a scanning electron microscope (SEM), the circularity was determined by the formula: circularity = 4πS / L ２ (where S is the particle area, and L is the particle circumferential length) of 0.6 or less, in a content of 30% by volume or more.

2. A host crystal comprising at least one metal element selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca), gallium (Ga) and sulfur (S), and a host crystal comprising at least one metal element selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca) and sulfur (S), and europium (Eu) as a luminescent center element; In observation using a scanning electron microscope (SEM), the circularity was determined by the formula: circularity = 4πS / L ２ (where S is the particle area, and L is the particle circumferential length) of 10% by volume or more of phosphor particles having a circularity of 0.4 or less.

3. 3. The phosphor powder according to claim 1, wherein the phosphor powder contains phosphor particles having a circularity of 0.8 or less at a content of 75% by volume or more.

4. 3. The phosphor powder according to claim 1, wherein the cumulative 50% diameter (D50) in a volume particle size distribution is 15.0 μm or less.

5. 3. The phosphor powder according to claim 1, wherein a cumulative 50% diameter (D50) in a volume particle size distribution is 10.0 μm or less.

6. The phosphor powder contains a crystal represented by the general formula: MGa 2 S 4 :Eu 2+ (wherein M is at least one element selected from the group consisting of Ba, Sr, and Ca), 3. The phosphor powder according to claim 1, wherein a ratio (XA / (XM+XA)) of the molar amount XA of the luminescent center element A to the sum (XM+XA) of the molar amount XM of the alkaline earth metal element M and the molar amount XA of the luminescent center element A contained in the phosphor powder is 0.05 or more and 0.30 or less.

7. A phosphor powder according to claim 1 or 2, wherein the cumulative 50% diameter (D50) in the volume particle size distribution is 2 μm or more and 7 μm or less.

8. A phosphor resin composition comprising the phosphor powder according to claim 1 or 2 and a resin.

9. A phosphor comprising the phosphor resin composition according to claim 8.

10. A light-emitting device comprising the phosphor according to claim 9 and an excitation source.

11. A light emitting device comprising the light emitting element according to claim 10.

12. A display device comprising the light-emitting device according to claim 10.

13. The display device according to claim 12, which is a miniLED display or a μLED display.