Phosphor, its manufacturing method and light-emitting device

Abstract

To provide a phosphor emitting green light with higher emission intensity.SOLUTION: A phosphor includes a first oxide containing Rb, Na, Li, Eu and Si in its composition. The first oxide has a composition in which a molar ratio of Rb to Si is 0.5 or more and less than 1, that of Na to Si is more than 0 and less than 0.5, that of Li to Si is more than 2 and less than 3.5, and that of a sum total content of Na and Li to Rb is 3 or more and 7 or less. In an X-ray diffraction pattern using a CuKα ray, the phosphor has a first diffraction peak in a Bragg angle range of 15.5° or more and 16.5° or less and a second diffraction peak in a Bragg angle range of 11.0° or more and 12.0° or less. When an intensity ratio of the second diffraction peak to the first diffraction peak is set to be α, α is in a range of 0.6 or more and 1.6 or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a phosphor, a method for producing the same, and a light-emitting device. [Background technology]

[0002] In light-emitting devices used as backlights for display devices, green-emitting phosphors with a narrower wavelength width of the emission spectrum are sometimes used to broaden the range of color reproducibility. For example, Patent Document 1 describes a lithium orthosilicate phosphor as a green-emitting phosphor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2019-527760 Summary of the Invention [Problem to be solved by the invention]

[0004] Green-emitting phosphors with higher emission intensity are in demand, and an object of one embodiment of the present disclosure is to provide a green-emitting phosphor with higher emission intensity. [Means for solving the problem]

[0005] A first aspect is a phosphor comprising a first oxide containing Rb, Na, Li, Eu, and Si in its composition. The first oxide has a composition in which the molar ratio of Rb to Si is 0.5 or more and less than 1, the molar ratio of Na to Si is greater than 0 and less than 0.5, the molar ratio of Li to Si is greater than 2 and less than 3.5, and the molar ratio of the total content of Na and Li to Rb is 3 or more and 7 or less. In an X-ray diffraction (XRD) pattern using CuKα radiation, the phosphor has a first diffraction peak at a Bragg angle in the range of 15.5° to 16.5° and a second diffraction peak at a Bragg angle in the range of 11.0° to 12.0°, and when the intensity ratio of the second diffraction peak to the first diffraction peak is defined as α, the value is in the range of 0.6 to 1.6.

[0006] The second aspect is a light emitting device comprising: a fluorescent member containing a first phosphor that includes the phosphor of the first aspect and has an emission peak wavelength in the range of 525 nm or more and 535 nm or less; and a light emitting element that has an emission peak wavelength in the wavelength range of 380 nm or more and 470 nm or less.

[0007] A third aspect is a method for producing a phosphor, comprising heat-treating a raw material mixture containing an Rb source, a Na source, a Li source, an Eu source, and a Si source at a temperature within the range of 400° C. to 800° C. In the raw material mixture, the molar ratio of Rb to Si is 0.5 or more and less than 1, the molar ratio of Na to Si is greater than 0 and less than 0.5, the molar ratio of Li to Si is greater than 2 and less than 3.5, the molar ratio of Eu to Si is greater than 0 and less than 0.3, and the molar ratio of the total content of Na and Li to Rb is 3 or more and 7 or less. At least one of the Rb source, Na source, Li source, Eu source, and Si source contained in the raw material mixture contains an oxide. [Effects of the Invention]

[0008] According to one aspect of the present disclosure, a green-emitting phosphor with higher emission intensity can be provided. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a schematic cross-sectional view showing an example of a light-emitting device. [Figure 2] 1 is a graph showing the relationship between the peak intensity ratio of XRD and the relative emission energy. [Figure 3] 1 is a graph showing the relationship between the peak intensity ratio of XRD and the emission peak wavelength. [Figure 4] 1 shows XRD spectra according to an example and a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0010] As used herein, the term "process" refers not only to an independent process, but also to processes that cannot be clearly distinguished from other processes, as long as the intended purpose of that process is achieved. Furthermore, when multiple substances corresponding to each component are present in a composition, the content of each component refers to the total amount of those multiple substances present in the composition, unless otherwise specified. Furthermore, the upper and lower limits of the numerical ranges described herein can be arbitrarily selected and combined. In this specification, in formulas representing the composition of phosphors or luminescent materials, multiple elements separated by a comma (,) mean that at least one of those multiple elements is contained in the composition. In addition, in formulas representing the composition of phosphors, the part before the colon (:) represents the host crystal, and the part after the colon (:) represents the activator element. In this specification, the relationship between color names and chromaticity coordinates, the relationship between light wavelength ranges and monochromatic light color names, etc., follows JIS Z8110. The half-width of a phosphor refers to the wavelength width (full width at half maximum; fwhm) of the emission spectrum of the phosphor where the emission intensity is 50% of the maximum emission intensity. Hereinafter, embodiments of the present invention will be described in detail. However, the embodiments shown below are intended to exemplify a phosphor, a manufacturing method thereof, and a light-emitting device for embodying the technical concept of the present invention, and the present invention is not limited to the phosphor, manufacturing method thereof, and light-emitting device shown below.

[0011] phosphor The phosphor includes a first oxide containing Rb, Na, Li, Eu, and Si. The first oxide has a composition in which the molar ratio of Rb to Si is 0.5 or more and less than 1, the molar ratio of Na to Si is greater than 0 and less than 0.5, the molar ratio of Li to Si is greater than 2 and less than 3.5, and the molar ratio of the total content of Na and Li to Rb is 3 or more and 7 or less. In an X-ray diffraction pattern using CuKα radiation, the phosphor has a first diffraction peak within a Bragg angle range of 15.5° to 16.5° and a second diffraction peak within a Bragg angle range of 11.0° to 12.0°, and the intensity ratio of the second diffraction peak to the first diffraction peak is within a range of 0.6 to 1.6.

[0012] The phosphor, which includes a first oxide having a specific composition and exhibits a specific X-ray diffraction pattern, emits green light with high emission intensity. In addition, the phosphor has a relatively narrow half-width, and when applied to a light-emitting device for use as a backlight for a display device, the phosphor can broaden the color reproducibility range of the display device.

[0013] The emission peak wavelength of the phosphor may be, for example, in the range of 525 nm to 535 nm, preferably 526 nm or more, or 527 nm or more. The upper limit of the emission peak wavelength of the oxide phosphor may be preferably 533 nm or less, or 531 nm or less. The half-width of the emission spectrum of the phosphor may be, for example, 50 nm or less, preferably 45 nm or less, or 42 nm or less. The lower limit of the half-width may be, for example, 30 nm or more, preferably 35 nm or more, or 38 nm or more.

[0014] The composition of the first oxide constituting the phosphor may preferably have a molar ratio of Rb to Si of 0.5 or more and less than 0.8, or more than 0.7 and less than 0.8. The molar ratio of Na to Si may be more than 0.1 and less than 0.3. The molar ratio of Li to Si may be more than 2.9 and less than 3.2. The molar ratio of Eu to Si may be more than 0 and less than 0.3. The molar ratio of the total content of Na and Li to Rb may be 3.75 or more and 6 or less.

[0015] The phosphor may have a composition represented by the following formula (I). Rb p Na q Li r SiO s :Eu t (I)

[0016] In formula (I), p, q, r, s and t may satisfy 0.5 ≦ p < 1, 0 < q < 0.5, 2 < r < 3.5, 3.25 < s < 4.5, 0 < t < 0.3, and 3 ≦ (q + r) / p ≦ 7, preferably 0.5 ≦ p < 0.8 or 0.7 < p < 0.8, 0.1 < q < 0.3, 2.9 < r < 3.2, 3.85 < s < 4.15, 0 < t < 0.3, and 3.75 ≦ (q + r) / p ≦ 6.

[0017] In the composition represented by formula (I), the number of moles of Si is taken as 1, but the composition of the phosphor may also be represented as in the following formula (Ia). Rb p1 Na q1 Li r1 (Li3SiO4) s1 O u1 :Eu t1 (Ia)

[0018] In formula (Ia), when s1 = 2, p1, q1, r1, s1, u1 and t1 may satisfy 1 ≦ p1 < 2, 0 < q1 < 1, 0 < r1 < 1, 0 < u#1 < 1, 0 < t1 < 0.6, and 0 ≦ (q1 + r1) / p1 ≦ 1.

[0019] The phosphor has a first diffraction peak in the range where the Bragg angle is 15.5° or more and 16.5° or less, and a second diffraction peak in the range where the Bragg angle is 11.0° or more and 12.0° or less in the X-ray diffraction pattern using CuKα rays. The phosphor may have an intensity ratio of the second diffraction peak to the first diffraction peak (hereinafter sometimes referred to as "intensity ratio α") in the range of 0.6 or more and 1.6 or less, and from the viewpoint of emission intensity, preferably in the range of 0.6 or more and 1.5 or less, or 0.6 or more and 1.4 or less.

[0020] The first diffraction peak is thought to originate from diffractions from (-2,0,1) and (2,0,1), for example. The second diffraction peak is thought to originate from diffractions from (2,0,0) and (0,0,1). For example, in RbLi(Li3SiO4)2:Eu (hereinafter sometimes abbreviated as "RbLi"), the first diffraction peak originates from a lattice plane composed of Rb and Li, while in RbNa(Li3SiO4)2:Eu (hereinafter sometimes abbreviated as "RbNa"), the first diffraction peak originates from a lattice plane composed of Rb and Na. Therefore, the intensity of the first diffraction peak is relatively stronger for "RbNa." Furthermore, (2,0,0) and (0,0,1) are lattice planes composed of Li in "RbLi," while in "RbNa," they are lattice planes composed of Na. On the other hand, (4,0,0) and (0,0,2), which are lattice planes shifted by half the interplanar spacing, are composed of Rb. Therefore, the intensity of the second diffraction peak depends on the difference in atomic scattering factors between Rb and Li in "RbLi," and between Rb and Na in "RbNa," so "RbLi" is relatively stronger. If the phosphor according to the first embodiment has a composition of Rb2NaLi(Li3SiO4)4:Eu, it is thought that it will have an intensity ratio intermediate between "RbLi" and "RbNa."

[0021] For example, it is known that when a host crystal of RbLi(Li3SiO4)2 is activated with Eu, the lattice volume increases, while when a host crystal of RbNa(Li3SiO4)2 is activated with Eu, the lattice volume decreases. When a host crystal of Rb2NaLi(Li3SiO4)4 is activated with Eu, two patterns are possible: one in which Eu substitutes for Na, and one in which Eu substitutes for Li. Therefore, it is thought that the change in lattice size due to Eu substitution in Rb2NaLi(Li3SiO4)4 is offset. It is thought that this size compensation effect improves the properties of the phosphor.

[0022] The volume average particle size of the phosphor may be, for example, 1 μm or more and 500 μm or less, preferably 5 μm or more and 100 μm or less, or 10 μm or more and 40 μm or less. The volume average particle size of the phosphor is calculated as the particle size corresponding to a cumulative frequency of 50% from the small diameter side in the volume-based particle size distribution. The volume-based particle size distribution is measured using a laser diffraction particle size distribution analyzer. The particle size distribution of the phosphor may have a single peak.

[0023] The phosphor may include a first oxide and an inorganic substance attached to the particle surface of the first oxide. By attaching an inorganic substance to the surface, the moisture resistance of the phosphor tends to be improved. Examples of inorganic substances include a second oxide different from the first oxide, a metal salt, a halide, a nitride, etc., and the phosphor may include at least one selected from the group consisting of these, preferably at least one selected from the group consisting of the second oxide and a metal salt. The inorganic substance attached to the first oxide may be a single type or a combination of two or more types. When two or more types of inorganic substances are used in combination, a mixture of the inorganic substances may be attached to the first oxide, or each inorganic substance may be attached sequentially to form a multilayer structure.

[0024] The second oxide may include at least one selected from the group consisting of Si, Al, Ti, Zr, Sn, and Zn. That is, the second oxide may include at least one selected from the group consisting of silicon oxide (e.g., SiOx, where x is 1 to 2, preferably 1.5 to 2, or approximately 2), aluminum oxide (e.g., Al2O3), titanium oxide (e.g., TiO2), zirconium oxide (e.g., ZrO2), tin oxide (e.g., SnO, SnO2, etc.), and zinc oxide (e.g., ZnO), and may include at least silicon oxide. The second oxide may consist of only one type, or may include two or more types.

[0025] The content of the second oxide in the phosphor may be 0.02% by mass or more and 30% by mass or less, and preferably 1% by mass or more and 15% by mass or less, based on the mass of the phosphor. The content of the second oxide in the phosphor can be measured, for example, by inductively coupled plasma (ICP) atomic emission spectroscopy.

[0026] The metal salt may include, for example, a rare earth phosphate, an alkaline earth metal phosphate, etc., and may include at least one selected from the group consisting of these. The rare earth phosphate may include at least one rare earth element selected from the group consisting of lanthanum (La), cerium (Ce), dysprosium (Dy), and gadolinium (Gd), and may preferably include at least lanthanum.

[0027] The content of the metal salt in the phosphor may be, for example, 0.1% by mass or more and 20% by mass or less, and preferably 0.2% by mass or more and 10% by mass or less, in terms of the content of the metal element.

[0028] The inorganic substance attached to the particle surface of the first oxide may be attached as inorganic substance particles and cover the surface of the first oxide, or the inorganic substance may cover the particle surface of the first oxide in the form of a film, or may be disposed on the surface of the first oxide as an inorganic substance layer.

[0029] Light-emitting device The light emitting device includes a fluorescent member containing a first phosphor having an emission peak wavelength in the range of 525 nm to 535 nm, and a light emitting element having an emission peak wavelength in the wavelength range of 380 nm to 470 nm. The first phosphor contained in the fluorescent member includes at least the phosphor according to the first aspect. By including a fluorescent member containing a specific phosphor, a light emitting device with high luminous flux can be configured.

[0030] An example of a light-emitting device will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of a light-emitting device according to this embodiment. This light-emitting device is an example of a surface-mounted light-emitting device. The light-emitting device 100 includes a light-emitting element 10 that emits light having an emission peak wavelength on the short wavelength side of visible light (for example, in the range of 380 nm to 470 nm) and a molded body 40 on which the light-emitting element 10 is mounted. The molded body 40 includes a first lead 20 and a second lead 30, and is integrally molded from a thermoplastic resin or a thermosetting resin. The molded body 40 has a recess having a bottom and side surfaces, and the light-emitting element 10 is mounted on the bottom surface of the recess. The light-emitting element 10 has a pair of positive and negative electrodes, which are electrically connected to the first lead 20 and the second lead 30 via wires 60. The light-emitting element 10 is sealed with a fluorescent member 50. The fluorescent member 50 contains a phosphor 70 that converts the wavelength of light from the light-emitting element 10. The phosphor 70 is required to contain at least a first phosphor including the phosphor of the first embodiment, and may further contain a second phosphor, a third phosphor, other light-emitting materials, etc. that emit light having an emission peak wavelength in a wavelength range different from that of the phosphor of the first embodiment in response to excitation light from the light-emitting element 10.

[0031] The fluorescent member may contain a resin and a phosphor. Examples of the resin constituting the fluorescent member include silicone resin and epoxy resin. The fluorescent member may further contain a light diffusing material in addition to the resin and phosphor. By including a light diffusing material, the directionality from the light emitting element can be alleviated and the viewing angle can be increased. Examples of the light diffusing material include silicon oxide, titanium oxide, zinc oxide, zirconium oxide, and aluminum oxide.

[0032] The light-emitting element emits light having an emission peak wavelength in the wavelength range of 380 nm to 470 nm, which is the short wavelength region of visible light. The light-emitting element may be an excitation light source capable of exciting an oxide phosphor. The light-emitting element preferably has an emission peak wavelength in the range of 380 nm to 460 nm, more preferably in the range of 410 nm to 460 nm, and even more preferably in the range of 430 nm to 460 nm. A semiconductor light-emitting element is preferably used as the excitation light source. By using a semiconductor light-emitting element as the excitation light source, a light-emitting device with high luminous efficiency and high input-to-output linearity can be obtained. For example, a semiconductor light-emitting element using a nitride-based semiconductor can be used as the semiconductor light-emitting element. The half-width of the emission peak in the emission spectrum of the light-emitting element is preferably, for example, 30 nm or less.

[0033] The light emitting device is configured to include a first phosphor containing the phosphor of the first aspect. Details of the phosphor of the first aspect included in the light emitting device are as described above. The first phosphor is contained, for example, in a fluorescent member covering an excitation light source. In a light emitting device in which the excitation light source is covered with a fluorescent member containing the first phosphor, a portion of the light emitted from the excitation light source is absorbed by the first phosphor and emitted as green light. By using an excitation light source that emits light having an emission peak wavelength in the range of 380 nm to 470 nm, the emitted light can be used more effectively, the loss of light emitted from the light emitting device can be reduced, and a light emitting device with high luminous efficiency can be provided.

[0034] The light emitting device may further include, in addition to the first phosphor, a second phosphor containing a phosphor other than the phosphor of the first embodiment. The second phosphor may absorb light from the light source and have an emission peak wavelength in the wavelength range of 500 nm or more and less than 600 nm. The second phosphor may be contained in the fluorescent member in the same manner as the first phosphor.

[0035] The second phosphor may have an emission peak wavelength in the wavelength range of 500 nm or more and less than 600 nm, and is preferably at least one selected from the group consisting of β-sialon phosphors, halosilicate phosphors, silicate phosphors, rare earth aluminate phosphors, and nitride phosphors. The β-sialon phosphor may have a composition represented by, for example, the following formula (IIa). The halosilicate phosphor may have a composition represented by, for example, the following formula (IIb). The silicate phosphor may have a composition represented by, for example, the following formula (IIc). The rare earth aluminate phosphor may have a composition represented by, for example, the following formula (IId). The nitride phosphor may have a composition represented by, for example, the following formula (IIe).

[0036] Si 6-t Al t O t N 8-t :Eu (IIa) (In the formula, t is a number satisfying 0 < t ≤ 4.2.) (Ca,Sr,Ba)8MgSi4O 16 (F,Cl,Br)2:Eu (IIb) (Ba,Sr,Ca,Mg)2SiO4:Eu (IIc) (Y,Lu,Gd,Tb)3(Al,Ga)5O 12 :Ce (IId) (La,Y,Gd)3Si6N 11 :Ce (IIe)

[0037] In addition to the first phosphor, the light-emitting device may include a light-emitting material having an emission peak wavelength in the wavelength range of 500 nm or more and less than 600 nm, for example, a perovskite-based light-emitting material having a composition represented by the following formula (IIf), and a chalcopyrite-based light-emitting material having a composition represented by the following formula (IIg). The light-emitting material having an emission peak wavelength in the wavelength range of 500 nm or more and less than 600 nm can be contained in the fluorescent member in the same manner as the first phosphor.

[0038] (Cs,FA,MA)Pb(F,Cl,Br,I)3(IIf) (In the formula, FA is formamidinium and MA is methylammonium.) Ag(Ga,In)S2(IIg)

[0039] In addition to the first phosphor, the light emitting device may further include a third phosphor having an emission peak wavelength in the wavelength range of 600 nm to 700 nm. The third phosphor absorbs light from the light source and emits, for example, red light. The third phosphor can be contained in the fluorescent member in the same manner as the first phosphor. The third phosphor may preferably be at least one selected from the group consisting of nitride phosphors and fluoride phosphors. The nitride phosphor may have a composition represented by, for example, the following formula (IIIa) or (IIIb). Fluoride phosphors will be described later.

[0040] (Sr,Ca)LiAl3N4:Eu(IIIa) (Ca,Sr)AlSiN3:Eu(IIIb)

[0041] The light emitting device may contain, in addition to the first phosphor, a luminescent material having an emission peak wavelength in the wavelength range of 600 nm to 700 nm, for example, a chalcopyrite-based luminescent material having a composition represented by the following formula (IIIc), or a phosphorus compound-based luminescent material having a composition represented by the following formula (IIId): The luminescent material having an emission peak wavelength in the wavelength range of 600 nm to 700 nm can be contained in the fluorescent member in the same way as the first phosphor.

[0042] (Cu,Ag)InS2(IIIc) (In,Ga,Al)P(IIId)

[0043] The third phosphor may more preferably be a fluoride phosphor. The fluoride phosphor may have a composition including an element M containing at least one element selected from the group consisting of Group 4 elements, Group 13 elements, and Group 14 elements, an alkali metal, Mn, and F. In the composition of the fluoride phosphor, when the moles of the alkali metal are taken as 2, the moles of Mn may be greater than 0 and less than 0.2, preferably 0.01 to 0.12. In addition, when the moles of the alkali metal are taken as 2, the moles of the element M may be greater than 0.8 and less than 1, preferably 0.88 to 0.99. In the composition of the fluoride particles, when the moles of the alkali metal are taken as 2, the moles of F may be greater than 5 and less than 7, preferably 5.9 to 6.1. The composition of the fluoride phosphor can be measured, for example, by inductively coupled plasma (ICP) atomic emission spectroscopy.

[0044] The element M in the composition of the fluoride phosphor includes at least one element selected from the group consisting of Group 4 elements, Group 13 elements, and Group 14 elements. Examples of Group 4 elements include titanium (Ti), zirconium (Zr), hafnium (Hf), etc., and at least one element selected from the group consisting of these may be included. Examples of Group 13 elements include boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), etc., and at least one element selected from the group consisting of these may be included. Examples of Group 14 elements include carbon (C), silicon (Si), germanium (Ge), tin (Sn), etc., and at least one element selected from the group consisting of these may be included. The element M may include at least one element from Group 14, and preferably at least one of Si and Ge. Furthermore, the element M may contain at least one type of Group 13 element and at least one type of Group 14 element, and preferably may contain at least Al and at least one of Si and Ge.

[0045] The alkali metal in the composition of the fluoride phosphor may contain at least one selected from the group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs). The alkali metal may also contain at least potassium (K) and at least one selected from the group consisting of lithium (Li), sodium (Na), rubidium (Rb), and cesium (Cs). The ratio of the number of moles of K to the total number of moles of alkali metals in the composition may be, for example, 0.90 or more, preferably 0.97 or more. The upper limit of the ratio of the number of moles of K may be, for example, 1 or 0.995 or less. In the composition of the fluoride particles, a portion of the alkali metals may be ammonium ions (NH4 + ) may be substituted. When a portion of the alkali metal is substituted with ammonium ions, the ratio of the number of moles of ammonium ions to the total number of moles of alkali metals in the composition may be, for example, 0.10 or less, and preferably 0.03 or less. The lower limit of the ratio of the number of moles of ammonium ions may be, for example, more than 0, and preferably 0.005 or more.

[0046] A first composition, which is one aspect of the composition of the fluoride phosphor, may contain at least one element selected from the group consisting of Group 4 elements and Group 14 elements as the element M, preferably at least one element selected from the group consisting of Group 14 elements, more preferably at least one of Si and Ge, and even more preferably at least Si. Furthermore, the first composition of the fluoride phosphor may have a total mole number of Si, Ge, and Mn of 0.9 to 1.1, preferably 0.97 to 1.03, relative to 2 moles of alkali metal.

[0047] The first composition of the fluoride phosphor may be a composition represented by the following formula (IIIe): A 1 b [M 1 1-a Mn a F c ] (IIIe)

[0048] In formula (IIIe), A 1 may contain at least one selected from the group consisting of Li, Na, K, Rb, and Cs. M 1 contains at least one of Si and Ge, and may further contain at least one element selected from the group consisting of Group 4 elements and Group 14 elements. Mn may be a tetravalent manganese ion. a satisfies 0 < a < 0.2, and b is [M 1 1-a Mn a F c the absolute value of the charge of the ion, and c satisfies 5 < c < 7.

[0049] A in formula (IIIe) 1 may further contain at least one selected from the group consisting of Li, Na, K, Rb, and Cs. Also, A 1 may be partially substituted with ammonium ions (NH4 + ). When a part of A 1 is substituted with ammonium ions, the ratio of the number of moles of ammonium ions to the total number of moles of A 1 in the composition may be, for example, 0.10 or less, preferably 0.05 or less, or 0.03 or less. The lower limit of the ratio of the number of moles of ammonium ions may exceed 0, for example, and may preferably be 0.005 or more.

[0050] In formula (IIIe), a is preferably 0.005 or more and 0.15 or less, or 0.015 or more and 0.1 or less. b may be, for example, 1.8 or more and 2.2 or less, preferably 1.95 or more and 2.05 or less. c may preferably be 5.5 or more and 6.5 or less, or 5.9 or more and 6.1 or less.

[0051] A second composition, which is one embodiment of the composition of the fluoride phosphor, may contain at least one selected from the group consisting of a Group 4 element and a Group 14 element as the element M, and at least one Group 13 element, preferably may contain at least one selected from the group consisting of Group 14 elements and at least one Group 13 element, and more preferably may contain at least Si and Al. Further, in the second composition of the fluoride phosphor, the total molar number of Si, Al, and Mn may be 0.9 or more and 1.1 or less, preferably 0.97 or more and 1.03 or less, with respect to 2 moles of the alkali metal. Furthermore, in the second composition of the fluoride phosphor, the molar number of Al may be more than 0 and 0.1 or less, preferably 0.003 or more and 0.015 or less, with respect to 2 moles of the alkali metal.

[0052] The second composition of the fluoride phosphor may be a composition represented by the following formula (IIIf). A 2 g [M 2 1-e Mn e F h (IIIf)

[0053] In formula (IIIf), A 2 may contain at least one selected from the group consisting of Li, Na, K, Rb, and Cs. M 2 contains at least Si and Al, and may further contain at least one element selected from the group consisting of a Group 4 element, a Group 13 element, and a Group 14 element. Mn may be a tetravalent manganese ion. e satisfies 0 < e < 0.2, and g is the absolute value of the charge of the [M 2 1-e Mn e F h ion, and h satisfies 5 < h < 7.

[0054] A in formula (IIIf) 2 may be partially substituted with an ammonium ion (NH4 + ). When a part of A 2 is substituted with an ammonium ion, A in the composition2 The ratio of the number of moles of ammonium ions to the total number of moles may be, for example, 0.10 or less, and preferably 0.03 or less. The lower limit of the ratio of the number of moles of ammonium ions may be, for example, more than 0, and preferably 0.005 or more.

[0055] In formula (IIIf), e is preferably 0.005 or more and 0.15 or less, or 0.015 or more and 0.1 or less. g may be, for example, 1.8 or more and 2.2 or less, and preferably 1.95 or more and 2.05 or less. h may preferably be 5.5 or more and 6.5 or less, or 5.9 or more and 6.1 or less.

[0056] Phosphor manufacturing method The method for producing a phosphor may include a preparation step of preparing a raw material mixture containing an Rb source, a Na source, a Li source, an Eu source, and a Si source, and a heat treatment step of heat treating the prepared raw material mixture at a temperature within the range of 400° C. to 800° C. In the raw material mixture, the molar ratio of Rb to Si may be 0.5 or more and less than 1, the molar ratio of Na to Si may be greater than 0 and less than 0.5, the molar ratio of Li to Si may be greater than 2 and less than 3.5, the molar ratio of Eu to Si may be greater than 0 and less than 0.3, and the molar ratio of the total content of Na and Li to Rb may be 3 or more and 7 or less. At least one of the Rb source, Na source, Li source, Eu source, and Si source constituting the raw material mixture may contain an oxide.

[0057] A phosphor having a desired composition and high luminescence intensity can be efficiently produced by heat-treating a raw material mixture having a predetermined composition at a predetermined temperature. The produced phosphor may include a first oxide containing Rb, Na, Li, Eu, and Si in its composition, and the first oxide may have a composition in which the molar ratio of Rb to Si is 0.5 or more and less than 1, the molar ratio of Na to Si is greater than 0 and less than 0.5, the molar ratio of Li to Si is greater than 2 and less than 3.5, and the molar ratio of the total content of Na and Li to Rb is 3 or more and 7 or less.

[0058] In the preparation step, a raw material mixture containing an Rb source, a Na source, a Li source, an Eu source, and a Si source is prepared. This raw material mixture can be obtained by measuring the Rb source, the Na source, the Li source, the Eu source, and the Si source to a desired blending ratio and then mixing them using a mixing method such as a ball mill, a mixing method using a mixer such as a Henschel mixer or a V-blender, or a mixing method using a mortar and pestle. Mixing can be performed by dry mixing or by wet mixing with the addition of a solvent or the like.

[0059] The Rb source constituting the raw material mixture may be a compound containing Rb, Rb alone, an alloy containing Rb, or the like, and may be at least one selected from the group consisting of these. Examples of the compound containing Rb include carbonates, oxides, and halides (fluorides, chlorides, etc.), and the mixture may contain at least one selected from the group consisting of these. Preferred examples of the compound containing Rb include rubidium carbonate and rubidium oxide. One Rb source may be used alone, or two or more may be used in combination.

[0060] The Na source constituting the raw material mixture may be a compound containing Na, simple Na, an alloy containing Na, or the like, and may be at least one selected from the group consisting of these. Examples of the Na-containing compound include carbonates, oxides, halides (fluorides, chlorides, etc.), and the mixture may contain at least one selected from the group consisting of these. Preferred examples of the Na-containing compound include sodium carbonate and sodium oxide. One Na source may be used alone, or two or more may be used in combination.

[0061] The Li source constituting the raw material mixture may be a compound containing Li, elemental Li, an alloy containing Li, or the like, and may be at least one selected from the group consisting of these. Examples of the compound containing Li include carbonates, oxides, halides (fluorides, chlorides, etc.), and the mixture may contain at least one selected from the group consisting of these. Preferred examples of the compound containing Li include lithium carbonate and lithium oxide. One Li source may be used alone, or two or more Li sources may be used in combination.

[0062] The Eu source constituting the raw material mixture may be a compound containing Eu, Eu alone, an alloy containing Eu, or the like, and may be at least one selected from the group consisting of these. Examples of the Eu-containing compound include oxides and halides (fluorides, chlorides, etc.), and may contain at least one selected from the group consisting of these. A preferred example of the Eu-containing compound is europium oxide. One Eu source may be used alone, or two or more Eu sources may be used in combination.

[0063] The Si source constituting the raw material mixture may be a compound containing Si, simple Si, an alloy containing Si, or the like, and may be at least one selected from the group consisting of these. Examples of the Si-containing compound include oxides, and the mixture may contain at least one selected from the group consisting of these. Preferred examples of the Si-containing compound include silicon oxide. One Si source may be used alone, or two or more Si sources may be used in combination.

[0064] The composition of the raw material mixture prepared in the preparation step may preferably be such that the molar ratio of Rb to Si is greater than 0.7 and less than 0.8, the molar ratio of Na to Si is greater than 0.1 and less than 0.3, the molar ratio of Li to Si is greater than 2.9 and less than 3.2, the molar ratio of Eu to Si is greater than 0 and less than 0.3, and the molar ratio of the total content of Na and Li to Rb is 4 or more and 5 or less.

[0065] At least one of the Rb source, Na source, Li source, Eu source, and Si source constituting the raw material mixture contains an oxide. The oxide may be contained in at least one of the Eu source and the Si source.

[0066] In the heat treatment step, the prepared raw material mixture is heat-treated at a predetermined temperature to obtain a heat-treated product. The heat-treated product obtained in the heat treatment step may contain the target phosphor. The heat treatment temperature in the heat treatment step may be, for example, 400°C or higher and 800°C or lower.

[0067] The heat treatment step may include raising the temperature to a predetermined heat treatment temperature, maintaining the heat treatment temperature, and decreasing the temperature from the heat treatment temperature. The rate of temperature increase from room temperature to the heat treatment temperature may be, for example, 0.1°C / min or more and 20°C / min or less, preferably 0.5°C / min or more or 1°C / min or more, and preferably 15°C / min or less or 10°C / min or less. The heat treatment time during which the heat treatment temperature is maintained may be, for example, 1 hour or more and 100 hours or less, preferably 50 hours or less or 20 hours or less. The rate of temperature decrease from the heat treatment temperature to room temperature may be, for example, 1°C / min or more and 600°C / min or less.

[0068] The heat treatment process may be performed in a single stage at a single heat treatment temperature, or in multiple stages at two or more identical or different heat treatment temperatures. When multiple heat treatments are performed, the heat treatments may be performed consecutively, or the temperature may be lowered after each heat treatment, and if necessary, treatments such as pulverization and mixing may be performed before the next heat treatment. From the viewpoint of the luminescence intensity of the phosphor, the heat treatment is preferably performed in multiple stages at two or more different heat treatment temperatures. It is more preferable to perform heat treatments consecutively at two or more different heat treatment temperatures, followed by treatments such as pulverization and mixing, and then perform another heat treatment. Here, "continuously performing heat treatments" means that, after the preceding heat treatment, the temperature is raised from the heat treatment temperature of the preceding heat treatment to the next heat treatment temperature without lowering the temperature (for example, a temperature difference of 350°C or more), pulverizing, mixing, etc., and the heat treatment is performed while maintaining the next heat treatment temperature.

[0069] When the heat treatment is performed in multiple stages, the heat treatment step may include, for example, a first heat treatment step in which the raw material mixture is subjected to a first heat treatment at a first temperature within the range of 400°C or higher and lower than 600°C to obtain a first heat-treated product, a second heat treatment step in which the first heat-treated product is subjected to a second heat treatment at a second temperature within the range of 600°C or higher and 800°C or lower, followed by pulverization and mixing to obtain a second heat-treated product, and a third heat treatment step in which the second heat-treated product is subjected to a third heat treatment at a third temperature within the range of 600°C or higher and 800°C or lower to obtain a third heat-treated product. In other words, the heat-treated product obtained in the heat treatment step in the phosphor manufacturing method may be the third heat-treated product.

[0070] In the first heat treatment step, the raw material mixture is heated, for example, from room temperature to a predetermined first temperature and maintained at the first temperature for a predetermined time to obtain a first heat-treated product. The first temperature may be preferably 450°C or higher, or 500°C or higher, and may be preferably 580°C or lower. The time for maintaining the first temperature may be, for example, 1 hour to 10 hours, preferably 2 hours to 5 hours.

[0071] In the second heat treatment step, the first heat-treated product is heated, for example, from the first temperature to a predetermined second temperature and maintained at the second temperature for a predetermined period of time. That is, the second heat treatment step may be performed consecutively with the first heat treatment step. The second temperature may be preferably 650°C or higher, or 700°C or higher, and may also be preferably lower than 800°C or 780°C or lower. The time for maintaining the second temperature may be, for example, 1 hour to 50 hours, preferably 2 hours to 20 hours. After maintaining the second temperature, the temperature may be lowered, for example, to room temperature or below. The intermediate heat-treated product obtained after maintaining the second temperature may be subjected to a pulverization treatment. For example, a method using a ball mill or a method using a mortar and pestle can be used for the pulverization treatment. This results in a second heat-treated product. By pulverizing the intermediate heat-treated product to obtain the second heat-treated product, the luminescence intensity of the final phosphor tends to be further improved. The pulverization treatment in the second heat treatment step may be carried out at a temperature of, for example, room temperature (for example, 25°C) or higher and 100°C or lower, preferably 50°C or lower.

[0072] In the third heat treatment step, the second heat-treated product is heated, for example, from room temperature to a predetermined third temperature and maintained at the third temperature for a predetermined time to obtain a third heat-treated product. The third temperature may be preferably 650°C or higher, or 700°C or higher, and may be preferably lower than 800°C or 780°C or lower. The time for maintaining the third temperature may be, for example, 1 hour to 50 hours, preferably 2 hours to 20 hours.

[0073] The heat treatment step in the method for producing a phosphor may further include at least one fourth heat treatment step after the third heat treatment step, in which the third heat-treated product is subjected to a fourth heat treatment at a fourth temperature to obtain a fourth heat-treated product. That is, the heat-treated product obtained in the heat treatment step in the method for producing a phosphor may be a fourth heat-treated product. Including the fourth heat treatment step in the method for producing a phosphor may result in a greater luminous intensity of the obtained phosphor.

[0074] In the fourth heat treatment step, the third heat-treated product is heated, for example, from room temperature to a predetermined fourth temperature and maintained at the fourth temperature for a predetermined time to obtain a fourth heat-treated product. The fourth temperature may be, for example, within a range of 600°C to 800°C. The fourth temperature may preferably be 650°C or higher, or 700°C or higher, and may preferably be lower than 800°C, or 780°C or lower. The time for maintaining the fourth temperature may be, for example, 1 hour to 50 hours, preferably 2 hours to 20 hours.

[0075] The atmosphere in the heat treatment step may be, for example, a reducing atmosphere. The reducing atmosphere may have a hydrogen gas content of 1% by volume or more and 30% by volume or less, preferably 3% by volume or more or 5% by volume or more, and preferably 20% by volume or less or 15% by volume or less. The heat treatment atmosphere may be a nitrogen-containing atmosphere. The nitrogen-containing atmosphere may have a nitrogen content of, for example, 70% by volume or more, preferably 80% by volume or 85% by volume or more.

[0076] The heat treatment of the raw material mixture can be carried out, for example, using a tubular furnace. The heat treatment of the raw material mixture can be carried out, for example, by filling the mixture into a crucible, boat, or the like made of aluminum oxide. In addition to aluminum oxide, carbon materials such as graphite, boron nitride (BN), molybdenum materials, and the like can also be used.

[0077] The heat-treated product obtained in the heat treatment step may be subjected to processes such as pulverization, dispersion, washing, filtration, and classification, and may be subjected to at least pulverization and classification. The pulverization process can be performed under dry conditions, for example, using a ball mill or a mortar and pestle, or under wet conditions by adding a solvent. The classification process can be performed using a dry sieve or a wet sieve. When using a wet sieve for classification, the heat-treated product or the heat-treated product after the pulverization process is dispersed in a liquid medium to obtain a slurry, which is then classified using a wet sieve to obtain a phosphor with the desired particle size. Examples of liquid media include organic solvents such as alcohol solvents (e.g., ethanol, isopropyl alcohol), ester solvents (e.g., ethyl acetate), hydrocarbon solvents (e.g., hexane, toluene), halogenated hydrocarbon solvents (e.g., chloroform, dichloroethane), and ether solvents (e.g., diethyl ether, diisopropyl ether), and mixtures thereof may also be used.

[0078] The method for producing a phosphor may include a surface treatment step of attaching an inorganic substance to the particle surface of the first oxide. Examples of the inorganic substance include a second oxide different from the first oxide, a metal salt, a halide, a nitride, etc., and the phosphor may contain at least one selected from the group consisting of these, preferably at least one selected from the group consisting of the second oxide and a metal salt. The surface treatment step can be appropriately selected from known methods depending on the inorganic substance to be attached.

[0079] For example, when the inorganic substance to be attached in the surface treatment step is a second oxide, the second oxide derived from the metal alkoxide can be attached to at least a portion of the particle surface of the first oxide by contacting particles of the first oxide with a metal alkoxide in a liquid medium. The metal alkoxide may be, for example, a metal alkoxide containing at least one selected from the group consisting of Si, Al, Ti, Zr, Sn, and Zn, or may be a metal alkoxide containing at least one of Si and Al. The aliphatic group of the alkoxide constituting the metal alkoxide may have, for example, 1 to 6 carbon atoms. For details of the method for attaching the second oxide to the particle surface of the first oxide, reference can be made to known techniques such as the so-called sol-gel method.

[0080] The metal alkoxide is preferably at least one selected from the group consisting of tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, trimethoxyaluminum, triethoxyaluminum, and triisopropoxyaluminum.

[0081] The amount of metal alkoxide used in the surface treatment step may be, for example, 1% by mass or more and 110% by mass or less with respect to the total mass of the first oxide.

[0082] Examples of the liquid medium include water; alcohol-based solvents such as methanol, ethanol, and isopropyl alcohol; nitrile-based solvents such as acetonitrile; and hydrocarbon-based solvents such as hexane. The liquid medium may contain at least water and an alcohol-based solvent. When the liquid medium contains an alcohol-based solvent, the content of the alcohol-based solvent in the liquid medium may be, for example, 60% by mass or more. The content of water in the liquid medium may be, for example, 40% by mass or less, preferably 20% by mass or less.

[0083] The liquid medium may further contain a pH adjuster. Examples of pH adjusters that can be used include alkaline substances such as ammonia, sodium hydroxide, and potassium hydroxide, and acidic substances such as hydrochloric acid, nitric acid, sulfuric acid, and acetic acid. When the liquid medium contains a pH adjuster, the pH of the liquid medium may be, for example, 1 or more and 6 or less under acidic conditions, or 8 or more and 12 or less under alkaline conditions.

[0084] The mass ratio of the liquid medium to the first oxide may be, for example, 100% by mass to 1000% by mass, preferably 100% by mass to 500% by mass, and more preferably 100% by mass to 300% by mass. When the mass ratio of the liquid medium is within the above range, the particle surfaces of the first oxide tend to be more uniformly covered with the second oxide.

[0085] The contact between the first oxide and the metal alkoxide can be carried out, for example, by adding the metal alkoxide to a suspension containing the first oxide. Stirring or the like may be performed at this time, if necessary. The contact temperature between the first oxide and the metal alkoxide may be, for example, 0°C or higher and 70°C or lower. The contact time may be, for example, 1 hour or higher and 12 hours or lower. The contact time includes the time required for adding the metal alkoxide.

[0086] In the surface treatment step, a heat treatment may be performed after the inorganic substance is attached to the particle surface of the first oxide. By performing the heat treatment, the stability of the first oxide to which the inorganic substance is attached may be further improved. The heat treatment temperature may be, for example, 100°C or higher and 400°C or lower. The heat treatment time may be, for example, 1 hour or higher and 50 hours or lower.

[0087] In the surface treatment step, the inorganic substance may be attached to the first oxide multiple times. When the inorganic substance is attached multiple times, the attached inorganic substances may be the same or different. [Example]

[0088] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0089] Example 1 Rb2CO3, Na2CO3, Li2CO3, SiO2, and Eu2O3 were used as the Rb, Na, Li, Si, and Eu sources, respectively. These were weighed and mixed to obtain a raw material mixture with a molar ratio of Rb:Na:Li:Si:Eu=0.75:0.25:3:1:0.04. The raw material mixture was filled into an aluminum oxide container and subjected to a first heat treatment at 550°C (first temperature) for two hours in a nitrogen / hydrogen mixed gas (9 / 1) atmosphere. The temperature was then increased to 750°C (second temperature) for a second heat treatment of 10 hours. The mixture was then cooled and pulverized, followed by a third heat treatment at 750°C (third temperature) for five hours. The resulting mixture was pulverized to obtain a powder of phosphor E1 of Example 1.

[0090] Example 2 Powder of phosphor E2 of Example 2 was obtained in the same manner as in Example 1, except that after the third heat treatment and pulverization in Example 1, a fourth heat treatment was further performed at 750°C (fourth temperature) for 5 hours and pulverization was then performed.

[0091] Example 3 Powder of phosphor E3 of Example 3 was obtained in the same manner as in Example 1, except that the heat treatment temperature of the second heat treatment (second temperature) and the heat treatment temperature of the third heat treatment (third temperature) were changed to 760°C.

[0092] Example 4 Powder of phosphor E4 of Example 4 was obtained in the same manner as in Example 2, except that the heat treatment temperatures of the second heat treatment (second temperature), the third heat treatment (third temperature), and the fourth heat treatment (fourth temperature) were changed to 760°C.

[0093] Example 5 A powder of phosphor E5 of Example 5 was obtained in the same manner as in Example 2, except that the molar ratio of each element in Example 2 was changed to Rb:Na:Li:Si:Eu=0.75:0.125:3.125:1:0.04.

[0094] Example 6 A powder of phosphor E6 of Example 6 was obtained in the same manner as in Example 3, except that in Example 4 the molar ratio of each element was changed to Rb:Na:Li:Si:Eu=0.75:0.125:3.125:1:0.04.

[0095] (Reference example) A β-SiAlON phosphor having an emission peak wavelength of 529 nm was designated as phosphor C0 of the reference example.

[0096] (Example 0) A powder of phosphor E0 of Example 0 was obtained in the same manner as in Example 1, except that the third heat treatment at 750° C. in Example 1 was not carried out.

[0097] (Comparative Example 2) Powder of phosphor C2 of Comparative Example 2 was obtained in the same manner as in Example 0, except that the raw material mixture was changed so that the molar ratio of each element in Example 0 was Rb:Na:Li:Si:Eu=0.5:0:3.5:1:0.04.

[0098] (Comparative Example 3) Powder of phosphor C3 of Comparative Example 3 was obtained in the same manner as in Example 1, except that the raw material mixture was changed so that the molar ratio of each element was Rb:Na:Li:Si:Eu=0.5:0:3.5:1:0.04.

[0099] Comparative Example 4 Powder of phosphor C4 of Comparative Example 4 was obtained in the same manner as in Example 2, except that the raw material mixture was changed so that the molar ratio of each element was Rb:Na:Li:Si:Eu=0.5:0:3.5:1:0.04.

[0100] (Comparative Example 5) Powder of phosphor C5 of Comparative Example 5 was obtained in the same manner as in Example 0, except that the raw material mixture was changed so that the molar ratio of each element was Rb:Na:Li:Si:Eu=1:0:3:1:0.08.

[0101] (Comparative Example 6) Powder of phosphor C6 of Comparative Example 6 was obtained in the same manner as in Example 1, except that the raw material mixture was changed so that the molar ratio of each element was Rb:Na:Li:Si:Eu=1:0:3:1:0.08.

[0102] (Comparative Example 7) Powder of phosphor C7 of Comparative Example 7 was obtained in the same manner as in Example 2, except that the raw material mixture was changed so that the molar ratio of each element was Rb:Na:Li:Si:Eu=1:0:3:1:0.08.

[0103] (Comparative Example 8) Powder of phosphor C8 of Comparative Example 8 was obtained in the same manner as in Example 0, except that the raw material mixture was changed so that the molar ratio of each element in Example 0 was Rb:Na:Li:Si:Eu=0.5:0.5:3:1:0.04.

[0104] Comparative Example 9 Powder of phosphor C9 of Comparative Example 9 was obtained in the same manner as in Example 1, except that the raw material mixture was changed so that the molar ratio of each element was Rb:Na:Li:Si:Eu=0.5:0.5:3:1:0.04.

[0105] (Comparative Example 10) Powder of phosphor C10 of Comparative Example 10 was obtained in the same manner as in Example 2, except that the raw material mixture was changed so that the molar ratio of each element was Rb:Na:Li:Si:Eu=0.5:0.5:3:1:0.04.

[0106] (Comparative Example 11) Rb2CO3, Li2CO3, SiO2, and Eu2O3 were used as the Rb, Li, Si, and Eu sources, respectively. The molar ratio of each element was Rb:Li:Si:Eu = 0.5:3.5:1:0.04, and the raw material mixture was weighed and mixed to obtain a total of 20 g. The raw material mixture was filled into an aluminum oxide container and heat-treated at 550°C for 5 hours in a nitrogen / hydrogen mixed gas (9 / 1) atmosphere, followed by pulverization. This was then re-heat-treated at 750°C for 10 hours. The resulting powder was then pulverized to obtain phosphor C11 of Comparative Example 11.

[0107] (Comparative Example 12) In Comparative Example 11, the molar ratio of each element was set to Rb:Li:Si:Eu=1:3:1:0.02, and the heat treatment was performed in only one stage at 1000°C for 4 hours. The same conditions were used to obtain powder of phosphor C12 for Comparative Example 12.

[0108] <Evaluation> (X-ray diffraction spectrum) The X-ray diffraction (XRD) spectra of the obtained phosphors were measured using a horizontal sample multipurpose X-ray diffractometer (product name: Ultima IV, manufactured by Rigaku Corporation; X-ray source: CuKα radiation (λ = 1.5418 Å), tube voltage: 40 kV, tube current: 40 mA). In the measured XRD spectra, a first diffraction peak with a Bragg angle of 15.5° to 16.5° and a second diffraction peak with a Bragg angle of 11.0° to 12.0° were identified, and the intensity ratio of the second diffraction peak to the first diffraction peak (intensity ratio α) was calculated. Figure 4 shows the XRD spectra for Example 1 and Comparative Examples 3, 7, and 9. In Figure 4, the first and second diffraction peaks are each enclosed by a solid line.

[0109] (luminous characteristics) The luminescence characteristics of the phosphor powder were measured using a quantum efficiency measurement system: QE-2000 (manufactured by Otsuka Electronics Co., Ltd.) with an excitation light wavelength of 450 nm. From the obtained emission spectrum, the relative luminescence energy (relative ENG: %), emission peak wavelength (λp: nm), and full width at half maximum (fwhm: nm) were calculated. The results are shown in Table 1. The relative luminescence energy (relative ENG (%)) was calculated based on the luminescence energy of the reference example (β-SiAlON).

[0110] Table 1 shows the composition ratios of Examples 0 to 2 and Comparative Examples 2 to 12 and the evaluation results for the purpose of comparing the properties due to differences in manufacturing methods. For Comparative Examples 2 and 11, the target phase was hardly formed, so the intensity ratio α was not calculated. Table 2 also shows the composition ratios of Examples 1 to 6 and Comparative Examples 3, 7, and 9 and the evaluation results for the purpose of comparing the properties due to composition changes. Figure 2 also shows the relationship between the intensity ratio α and the relative emission energy (relative ENG). Figure 3 shows the relationship between the intensity ratio α and the emission peak wavelength (λp).

[0111] [Table 1]

[0112] As shown in Table 1, it can be seen that the emission energy increased with the three-stage heat treatment for all compositions. Furthermore, further improvement was observed with the four-stage heat treatment for some compositions. In Comparative Example 2, the target phase was hardly produced, and the emission spectrum differed from the other Examples and Comparative Examples due to the presence of by-products, resulting in a significantly wider half-width compared to them. In Comparative Example 11, the second heat treatment was not performed, so a phosphor with sufficient properties could not be reproducibly obtained even when the synthesis scale was increased. In Comparative Example 12, the first temperature was relatively high, causing the phosphor to melt. Therefore, a powerful crushing process was required to obtain phosphor powder, which resulted in poor workability.

[0113] [Table 2]

[0114] As shown in Table 2, the phosphors obtained in Examples 1 to 6 have larger emission energies and narrower half-widths compared to the Reference Example and Comparative Examples 3, 7, and 9. Furthermore, as shown in Figure 2, it can be seen that the relative ENG becomes higher when the range of the intensity ratio α is 0.6≦α≦1.6.

[0115] The reason for this is speculated as follows. First, it is thought that the phosphor has a structure in which, among the composition represented by ALiSiO (where A is the remaining alkali metal), LiSiO forms a three-dimensional framework, and the resulting channels are occupied by the A element. In Comparative Example 3, channels occupied by Rb and channels occupied by Li are alternately arranged, and in Comparative Example 9, channels occupied by Rb and channels occupied by Na are alternately arranged (channels occupied by Rb are referred to as R channels, and channels occupied by Li and Na are referred to as LN channels). The XRD peak between 11° and 12° is due to diffraction from the (2,0,0) and (0,0,1) planes, and the peak between 15.5° and 16.5° is due to diffraction from the (-2,0,1) and (2,0,1) planes. The (2,0,0) and (0,0,1) planes are lattice planes composed of atoms in the LN channel, while the (4,0,0) and (0,0,2) planes, which are 1 / 2 the interplanar spacing, are composed of Rb in the R channel. Therefore, the peak intensity at 11° depends on the difference in atomic scattering factors between Rb and the alkali metals in the LN channel, and is therefore strongest in Comparative Example 3, where Li occupies the LN channel. On the other hand, the (-2,0,1) and (2,0,1) planes are lattice planes that pass through atoms in both the R channel and the LN channel. Therefore, the peak intensity depends on the sum of the atomic scattering factors, and is therefore strongest in Comparative Example 9, where Na occupies the LN channel. In other words, the intensity ratio α is related to the ratio of Li to Na occupying the LN channel. It is presumed that the phosphors shown in the examples have both Li and Na occupying the LN channel.

[0116] When the activator element is substituted into the host crystal, it is thought that in Comparative Example 3, the lattice constant of the crystal increases because it is substituted into the Li site, and in Comparative Example 9, the lattice constant decreases because it is substituted into the Na site. Therefore, in the compositions of the examples, it is presumed that the strain that would be generated in the host crystal when the activator element occupies the Li site and when it occupies the Na site is canceled out, resulting in improved properties. Another factor that may have contributed to the improved properties is that the probability of the activator element being erroneously substituted into the Rb site was reduced by adding excess Rb.

[0117] Furthermore, as shown in Figure 3, it can be seen that the emission peak wavelength becomes longer as the intensity ratio α increases. This is presumably because, for example, an increase in the Li content reduces the lattice constant of the host, which increases the effect of crystal field splitting on the activator element, stabilizing the excitation level and reducing the energy difference between the ground level and the excitation level.

[0118] Example 7 The powder of phosphor E4 obtained in Example 4 was ball milled using an organic solvent as a dispersion medium. Then, coarse particles were removed using a sieve with a mesh size of 41 μm, and then fine particles were removed using a sieve with a mesh size of 15 μm. The powder was dried to obtain a powder of phosphor E7 of Example 7, which had been subjected to a classification treatment.

[0119] Example 8 A powder of phosphor E8 of Example 8 was obtained under the same conditions as in Example 7, except that the classification operation after dispersion was changed to a sieve with a mesh size of 41 μm to remove fine particles.

[0120] Example 9 A powder of phosphor E9 of Example 9 was obtained under the same conditions as in Example 7, except that the classification procedure after dispersion was changed to a sieve with 15 μm openings to remove coarse particles.

[0121] <Evaluation> (Volume average particle size) The volume average particle size (median diameter: Dm) was calculated as the particle size corresponding to a cumulative frequency of 50% from the small diameter side in the volume-based particle size distribution measured using a laser diffraction particle size distribution analyzer (e.g., MALVERN, product name: MASTER SIZER3000). The results are shown in Table 3.

[0122] [Table 3]

[0123] As shown in Table 3, the use of an organic solvent suppresses deterioration of properties due to heat treatment, while classification allows the particle size to be adjusted to suit the application, from small to large. For example, when comparing only the luminescence properties, Example 8 has better properties, but because Example 8 has a larger particle size than Example 7, it may not be suitable as a phosphor for use in light-emitting devices that require phosphors with smaller particle sizes.

[0124] Example 10 A light emitting device was fabricated by a conventional method using phosphor E2 obtained in Example 2 as the first phosphor and a phosphor having a composition represented by K2SiF6:Mn as the third phosphor, in combination with an LED having an emission peak wavelength of 450 nm as the light emitting element. At that time, the fluorescent member containing the phosphor and resin was adjusted so that the chromaticity coordinates (x, y) of the emitted color were x = 0.262, y = 0.223.

[0125] (Comparative Examples 13 to 15) Light emitting devices were fabricated in the same manner as in Example 10, except that the first phosphor used was changed as shown in Table 4.

[0126] <Evaluation> The chromaticity coordinates and luminous flux of the obtained light-emitting device were measured. The luminous flux of the light-emitting device was measured using an integral total luminous flux measuring device. Table 4 also shows the ratio of the alkali metals charged during phosphor production, the chromaticity coordinates of the obtained light-emitting device, the luminous flux ratio, and the range of color reproducibility. The luminous flux ratio was calculated based on Comparative Example 15, which used the phosphor of the Reference Example. The range of color reproducibility indicates the coverage rate (%) of the BT2020 standard.

[0127] [Table 4]

[0128] As shown in Table 4, using phosphor E2 increases the luminous flux and color reproducibility range compared to using phosphor C3. The improvement in luminous flux is thought to be due to the increased luminous energy of the phosphor used, and the increased color reproducibility range is thought to be due to the shift in the peak emission wavelength of the phosphor used to shorter wavelengths. Furthermore, luminous flux improves compared to using phosphor C9. This is presumably due to the increased luminous energy of the phosphor used.

[0129] Example 11 15 g of phosphor E7 produced in Example 7 was weighed out and added to a solution made by mixing 27 mL of ethanol, 6.2 mL of ammonia water, and 3.3 mL of pure water. While stirring with a stirrer, the liquid temperature was maintained at room temperature (25°C) to form a reaction mother liquid. 0.8 g of tetraethoxysilane (TEOS:Si(OC2H5)4) was weighed out and added dropwise to the stirring reaction mother liquid over approximately 2 hours. Stirring was then continued for 1 hour and then stopped. The resulting precipitate was separated into solid and liquid, washed with ethanol, and dried to obtain phosphor E11 of Example 11, which had a silicon dioxide (SiO2) film attached.

[0130] Example 12 The phosphor E11 produced in Example 11 was subjected to a heat treatment in the atmosphere at a temperature of 350° C. for 10 hours, thereby obtaining a phosphor E12 of Example 12.

[0131] Example 13 15 g of phosphor E7 produced in Example 7 and 0.8 g of TEOS were weighed and added to 27 mL of ethanol. Then, the mixture was stirred with a stirrer for 3 hours while maintaining the liquid temperature at 50°C. The precipitate obtained after stirring was subjected to solid-liquid separation, washed with ethanol, and dried to obtain phosphor E13 of Example 13.

[0132] Example 14 A film made of silicon dioxide (SiO 2 ) was further adhered to the phosphor E13 produced in Example 13 under the same conditions as in Example 13 to produce phosphor E14 of Example 14.

[0133] In all of Examples 11 to 14, a film made of silicon dioxide could be attached to the surface of the phosphor. It is believed that these films function as protective films that can suppress deterioration of the phosphor due to the external environment. [Industrial Applicability]

[0134] The phosphor of the present disclosure can be used in light-emitting devices, particularly those that use light-emitting diodes as excitation light sources, and can be suitably used in, for example, lighting light sources, light sources for LED displays or liquid crystal backlights, traffic lights, illuminated switches, various sensors, various indicators, small strobes, and the like. [Explanation of symbols]

[0135] 10: light emitting element, 20: first lead, 30: second lead, 40: molded body, 50: fluorescent member, 60: wire, 70: phosphor, 100: light emitting device.

Claims

1. a first oxide containing Rb, Na, Li, Eu, and Si in its composition; the first oxide has a composition in which a molar ratio of Rb to Si is 0.5 or more and less than 1, a molar ratio of Na to Si is greater than 0 and less than 0.5, a molar ratio of Li to Si is greater than 2 and less than 3.5, and a molar ratio of the total content of Na and Li to Rb is 3 or more and 7 or less, In an X-ray diffraction pattern using CuKα radiation, the crystal has a first diffraction peak in a Bragg angle range of 15.5° or more and 16.5° or less and a second diffraction peak in a Bragg angle range of 11.0° or more and 12.0° or less, A phosphor in which, when the intensity ratio of the second diffraction peak to the first diffraction peak is defined as α, α is in the range of 0.6 to 1.

6.

2. 2. The phosphor according to claim 1, having a composition in which the molar ratio of Rb to Si is 0.5 or more and less than 0.8, the molar ratio of Na to Si is greater than 0.1 and less than 0.3, the molar ratio of Li to Si is greater than 2.9 and less than 3.2, the molar ratio of Eu to Si is greater than 0 and less than 0.3, and the molar ratio of the total content of Na and Li to Rb is 3.75 or more and 6 or less.

3. 2. The phosphor according to claim 1, having a composition represented by the following formula (I): Rb ｐ Na ｑ Li ｒ SiO ｓ :Eu ｔ (I) (In formula (I), p, q, r, s, and t satisfy the relationships 0.5≦p<1, 0<q<0.5, 2<r<3.5, 3.25<s<4.5, 0<t<0.3, and 3≦(q+r) / p≦7.)

4. 4. The phosphor according to claim 3, wherein p, q, r, s, and t satisfy 0.5≦p<0.8, 0.1<q<0.3, 2.9<r<3.2, 3.85<s<4.15, 0<t<0.3, and 3.75≦(q+r) / p≦6.

5. 5. A light emitting device comprising: a fluorescent member containing a first phosphor comprising the phosphor according to claim 1 and having an emission peak wavelength in the range of 525 nm to 535 nm; and a light emitting element having an emission peak wavelength in the wavelength range of 380 nm to 470 nm.

6. The light emitting device according to claim 5 , wherein the fluorescent member further includes a second phosphor or a light emitting material having an emission peak wavelength in a wavelength range of 500 nm or more and less than 600 nm.

7. The light emitting device according to claim 5 , wherein the fluorescent member further includes a third phosphor or a light emitting material having an emission peak wavelength in a wavelength range of 600 nm to 700 nm.

8. 8. The light-emitting device according to claim 7, wherein the third phosphor comprises an element M including at least one element selected from the group consisting of Group 4 elements, Group 13 elements, and Group 14 elements, an alkali metal, Mn, and F, and has a composition in which, when the number of moles of the alkali metal is 2, the number of moles of Mn is more than 0 and less than 0.2, the number of moles of the element M is more than 0.8 and less than 1, and the number of moles of F is more than 5 and less than 7.

9. A method for producing a phosphor, the method comprising: heat-treating a raw material mixture containing a Rb source, a Na source, a Li source, a Eu source, and a Si source at a temperature in the range of 400° C. to 800° C., the raw material mixture has a molar ratio of Rb to Si of 0.5 or more and less than 1, a molar ratio of Na to Si of greater than 0 and less than 0.5, a molar ratio of Li to Si of greater than 2 and less than 3.5, a molar ratio of Eu to Si of greater than 0 and less than 0.3, and a molar ratio of the total content of Na and Li to Rb of 3 or more and 7 or less, and at least one of the Rb source, Na source, Li source, Eu source, and Si source contains an oxide; the phosphor has, in an X-ray diffraction pattern using CuKα radiation, a first diffraction peak within a Bragg angle range of 15.5° or more and 16.5° or less and a second diffraction peak within a Bragg angle range of 11.0° or more and 12.0° or less; a ratio of the intensity of the second diffraction peak to the intensity of the first diffraction peak is defined as α, and α is within a range of 0.6 to 1.

6.

10. 10. The method for producing a phosphor according to claim 9, wherein the raw material mixture has a molar ratio of Rb to Si that is greater than 0.7 and less than 0.8, a molar ratio of Na to Si that is greater than 0.1 and less than 0.3, a molar ratio of Li to Si that is greater than 2.9 and less than 3.2, a molar ratio of Eu to Si that is greater than 0 and less than 0.3, and a molar ratio of the total content of Na and Li to Rb that is 4 or more and 5 or less.

11. The heat treatment includes subjecting the raw material mixture to a first heat treatment at a first temperature within a range of 400°C or higher and lower than 600°C to obtain a first heat-treated product; subjecting the first heat-treated product to a second heat treatment at a second temperature in the range of 600°C to 800°C, and then lowering the temperature to obtain a second heat-treated product; 11. The method for producing a phosphor according to claim 9, further comprising: subjecting the second heat-treated product to a third heat treatment at a third temperature within a range of 600°C or more and 800°C or less to obtain a third heat-treated product.

12. 12. The method for producing a phosphor according to claim 9, wherein the phosphor obtained by heat-treating the raw material mixture includes a first oxide containing Rb, Na, Li, Eu, and Si in its composition, and the first oxide has a composition in which the molar ratio of Rb to Si is 0.5 or more and less than 1, the molar ratio of Na to Si is greater than 0 and less than 0.5, the molar ratio of Li to Si is greater than 2 and less than 3.5, and the molar ratio of the total content of Na and Li to Rb is 3 or more and 7 or less.

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