Silicate fluorescent material, light emitting device, and method for producing silicate fluorescent material

Abstract

To provide a silicate fluorescent material, a light emitting device, and a method for producing a silicate fluorescent material.SOLUTION: A silicate fluorescent material has a composition represented by the following formula (1): A11-w-xA2wM1x(Li3SiO4):Euy (1), wherein A1 represents at least one first alkali element selected from the group consisting of Rb and Cs, A2 represents at least one second alkali element selected from the group consisting of K, Na, and Li, M1 represents at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Y, and La, and w, x, and y satisfy 0<w<1.0, 0<x≤0.125, w+x≤1.0, and 0<y≤0.08.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a silicate phosphor, a light-emitting device, and a method for producing a silicate phosphor.

Background Art

[0002] For example, a light-emitting device used for the backlight of a display device is required to have a wider range of color reproducibility. In order to widen the range of color reproducibility, a phosphor having a narrower emission peak width (full width at half maximum) in the emission spectrum may be required as the phosphor.

[0003] As a phosphor that emits green light and is used in a light-emitting device, for example, the activating element is europium, and the formula is Si 6-z Al z O z N 8-z (where z is 0 < z ≤ 4.2) and a β-sialon phosphor having such a composition can be mentioned.

[0004] Further, for example, Patent Document 1 discloses an orthosilicate phosphor in which the activating element is europium as a phosphor that emits green light.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] A phosphor that emits green light is required to have an emission peak with a narrow full width at half maximum in the emission spectrum, high emission intensity, and high light resistance that reduces light deterioration caused by continuous irradiation of excitation light in order to widen the range of color reproducibility.

[0007] The present disclosure aims to provide a silicate phosphor having a narrow full width at half maximum in the emission spectrum, high emission intensity, and high light resistance, a light-emitting device, and a method for producing the silicate phosphor.

Means for Solving the Problems

[0008] The first aspect is a silicate phosphor having a composition represented by the following formula (1). A 1 1-w-x A 2 w M 1 x (Li3SiO4):Eu y (1) (In the above formula (1), A 1 is at least one first alkali element selected from the group consisting of Rb and Cs, and A 2 is at least one second alkali element selected from the group consisting of K, Na, and Li, and M 1 is at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Y, and La, and w, x, and y satisfy 0 < w < 1.0, 0 < x ≤ 0.125, w + x ≤ 1.0, and 0 < y ≤ 0.08 respectively.)

[0009] The second aspect is a light-emitting device including the silicate phosphor and a light-emitting element having an emission peak wavelength within a range of 300 nm or more and 500 nm or less, and irradiating the silicate phosphor with excitation light.

[0010] The third aspect is a first compound containing at least one first alkali element A 1 selected from the group consisting of Rb and Cs, a second compound containing at least one second alkali element A 2 selected from the group consisting of K, Na, and Li, and at least one element M 1A third compound containing the same, a fourth compound containing Li, a fifth compound containing Si, and a sixth compound containing Eu, wherein at least one compound from the first compound to the sixth compound is an oxide, preparing a raw material; the first alkali element A contained in the first compound 1 the second alkali element A contained in the second compound 2 the element M contained in the third compound 1 Li contained in the fourth compound, Si contained in the fifth compound, and Eu contained in the sixth compound are mixed so as to satisfy the molar ratio in the composition represented by the following formula (1) to obtain a raw material mixture; the raw material mixture is heat-treated for the first time at a first temperature within the range of 400 °C or higher and 800 °C or lower in a reducing atmosphere to obtain a first heat-treated product having the composition represented by the following formula (1). This is a method for producing a silicate phosphor. A 1 1-w-x A 2 w M 1 x (Li3SiO4):Eu y (1) (In the above formula (1), w, x, and y each satisfy 0 < w < 1, 0 < x ≤ 0.125, w + x ≤ 1.0, and 0 < y ≤ 0.08.)

Advantages of the Invention

[0011] According to the present disclosure, it is possible to provide a silicate phosphor having a narrow full width at half maximum emission peak in the emission spectrum, high emission intensity, and high light resistance, a light-emitting device, and a method for producing a silicate phosphor.

Brief Description of the Drawings

[0012] [Figure 1] It is a schematic cross-sectional view showing an example of a light-emitting device. [Figure 2] It is a diagram showing the emission spectra of each silicate phosphor according to Examples 1 to 4 and the silicate phosphor according to Comparative Example 1. [Figure 3] It is a diagram showing the emission spectra of the silicate phosphor according to Example 7 and the silicate phosphor according to Comparative Example 2. [Figure 4] 1 is a graph showing the luminescence maintenance rates of the silicate phosphors according to Examples 2 and 7 and the silicate phosphor according to Comparative Example 1 after 500 hours of irradiation with excitation light. [Figure 5] FIG. 2 is a diagram showing thermoluminescence spectra of the silicate phosphors according to Examples 3 and 7 and the silicate phosphor according to Comparative Example 1. [Figure 6] 1 shows X-ray diffraction patterns of silicate phosphors according to Examples 1 to 11 and silicate phosphors according to Comparative Examples 1 and 2. [Figure 7] 1 shows an enlarged X-ray diffraction pattern of the silicate phosphor according to Examples 1 to 4 in the region where the diffraction angle 2θ (°) is from 37° to 37.8°. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a silicate phosphor, a light-emitting device, and a method for manufacturing a silicate phosphor according to the present disclosure will be described based on embodiments. However, the embodiments shown below are merely examples for embodying the technical concept of the present invention, and the present invention is not limited to the silicate phosphor, the light-emitting device, and the method for manufacturing a silicate phosphor described below. In this specification, the relationship between color names and chromaticity coordinates, the relationship between light wavelength ranges and color names of monochromatic light, etc., conforms to JIS Z8110. In this specification, the full width at half maximum refers to the wavelength width that is 50% of the emission intensity at the emission peak wavelength that exhibits the maximum emission intensity in the emission spectrum.

[0014] The silicate phosphor has a composition represented by the following formula (1). A 1 1-w-x A 2 w M 1 x (Li3SiO4):Eu y (1) (In the formula (1), A 1 is at least one first alkali element selected from the group consisting of Rb and Cs, and A 2is at least one second alkali element selected from the group consisting of K, Na, and Li, and M 1 is at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Y, and La, and w, x, and y satisfy 0 < w < 1.0, 0 < x ≤ 0.125, w + x ≤ 1.0, and 0 < y ≤ 0.08, respectively.)

[0015] The silicate phosphor has a crystal structure including a tetrahedral structure of coordination number 4 composed of a silicate (SiO4) represented by (Li3SiO4) in formula (1) and lithium oxide, and a cubic structure of coordination number 8 composed of an alkali element and oxygen. In the silicate phosphor, oxygen constituting the tetrahedral structure of coordination number 4 composed of the silicate (SiO4) represented by (Li3SiO4) in formula (1) and lithium oxide and oxygen constituting the cubic structure of coordination number 8 composed of an alkali element and oxygen are shared. The silicate phosphor has a structure in which a cubic structure with oxygen coordinated in an octahedron around an alkali element is inserted between the tetrahedral structures composed of the silicate (SiO4) represented by (Li3SiO4) in formula (1) and lithium oxide. The tetrahedral structure of coordination number 4 composed of the silicate (SiO4) and lithium oxide has gaps of different sizes, and at least one first alkali element A 1 centered on A 1 a large cubic structure represented by O8 (RbO8 or CsO8), and at least one second alkali element A 2 centered on A 2 a small cubic structure represented by O8 (KO8, NaO8, or LiO8) having an ionic radius not exceeding the ionic radius of K exists.

[0016] Eu, which is an activating element of the silicate phosphor, is the first alkali element A 1 or the second alkali element A 2It is presumed that the silicate phosphor having the composition represented by the formula (1) is preferably excited by light in the wavelength range of 300 nm to 500 nm and emits fluorescence having an emission peak wavelength in the range of 520 nm to 560 nm, and therefore the activator element Eu is preferably substituted with a second alkali element A, which is at least one element selected from the group consisting of K, Na, and Li, having an ionic radius closer to the ionic radius of Eu. 2 It is assumed that Eu, an activation element, is easily substituted by the first alkali element A. 1 or second alkali element A 2 Eu, an activator element contained in silicate phosphors, is substituted with divalent Eu 2+ contributes to the emission of light.

[0017] Silicate phosphors are composed of a four-coordinate tetrahedral structure of silicate (SiO4) and lithium oxide, and contain the first alkali element A, which has an ionic radius larger than that of K. 1 A large cubic structure with a center and a second alkali element A with an ionic radius smaller than the ionic radius of K. 2 The oxygen atoms that make up the tetrahedral structure of silicate (SiO4) and lithium oxide, and the oxygen atoms that make up the large and small cubic structures, are shared, so the crystal structure is easily distorted and defects are easily generated in the crystal structure. When defects occur in the crystal structure of a silicate phosphor, the first alkali element A 1 Replaced by Eu 2+ is trivalent Eu to achieve charge balance. 3+ Divalent Eu contained in silicate phosphors is easily converted into 2+ However, trivalent Eu does not contribute to luminescence. 3+ When the temperature changes to , the emission intensity decreases.

[0018] The silicate phosphor having the composition represented by the formula (1) contains a first alkali element A 1 or second alkali element A 2 A part of the element M is a divalent or trivalent element 1The silicate phosphor having the composition represented by the formula (1) has a composition in which the first alkali element A 1 or second alkali element A 2 A part of the element M is a divalent or trivalent element 1 To achieve charge balance, divalent Eu 2+ is trivalent Eu 3+ The divalent Eu that contributes to the emission in silicate phosphors no longer needs to be converted to 2+ This can maintain the light emission intensity and reduce the decrease in the light emission intensity.

[0019] In the silicate phosphor having the composition represented by the formula (1), the first alkali element A 1 A divalent or trivalent element M that replaces 1 is the first alkali element A 1 Element M with an ionic radius close to that of 1 Preferably, the first alkali element A is at least one selected from the group consisting of Rb and Cs. 1 A divalent or trivalent element M that replaces 1 is at least one element M selected from the group consisting of Sr, Ba, Y and La. 1 It is preferable that:

[0020] In the silicate phosphor having the composition represented by the formula (1), the second alkali element A 2 Divalent element M that replaces 1 is the second alkali element A 2 Element M with an ionic radius close to that of 1 It is preferable that the second alkali element A is at least one selected from the group consisting of K, Na, and Li. 2 Divalent element M that replaces 1 is at least one element M selected from the group consisting of Mg and Ca 1 The second alkali element A is preferably 2 is the first alkali element A 1 Compared to the second alkali element A, the ionic radius is smaller. 2 Element M to be replaced by1 is not a trivalent element, but a secondary alkali element A 2 Divalent element M with an ionic radius close to that of 1 It is preferable that:

[0021] In the silicate phosphor having the composition represented by the formula (1), the first alkali element A 1 or second alkali element A 2 A divalent or trivalent element M that replaces 1 In order to achieve charge balance, the first alkali element A 1 Element M to be replaced by 1 Or, the second alkali element A 2 Element M to be replaced by 1 The first alkali element A 1 and second alkali element A 2 Two or more elements M that replace each of 1 The first alkali element A 1 and second alkali element A 2 A divalent or trivalent element M replacing at least one of 1 is at least one element M selected from the group consisting of Mg, Ca, Sr, Ba, Y and La. 1 In the silicate phosphor having the composition represented by the formula (1), the element M 1 is an element with a small ionic radius, M 1 It is easier to replace the alkali elements, and the first alkali element A 1 The second alkali element A has an ionic radius smaller than 2 At least one element M selected from the group consisting of Mg and Ca, which is easily substituted for 1 In the silicate phosphor having the composition represented by the formula (1), the second alkali element A is preferably 2 Element M to be replaced by 1 In the silicate phosphor having the composition represented by the formula (1), for example, the second alkali element A is preferably Mg. 2 If is Na, the second alkali element A 2 Divalent element M replacing1 It is preferably Mg which has an ionic radius close to that of Na.

[0022] In the silicate phosphor having the composition represented by the formula (1), the variable w represents the molar ratio of the second alkali element A in 1 mol of the composition represented by the formula (1). 2 The silicate phosphor preferably has a variable w of more than 0 and less than 1.0 (0 < w < 1.0), preferably in the range of 0.1 or more and 0.24 or less (0.1 ≦ w ≦ .24), more preferably in the range of 0.12 or more and 0.23 or less (0.12 ≦ w ≦ 0.23). If the variable w representing the molar ratio of the second alkali element A2 in 1 mol of the composition represented by the formula (1) of the silicate phosphor is in the range of more than 0 and less than 1.0 (0 < w < 1.0), in the formula (1), between the silicate (SiO4) represented by (Li3SiO4) and the four-coordinate tetrahedral structure composed of lithium oxide, the first alkali element A 1 centered large cubic structure and the second alkali element A 2 centered small cubic structure are arranged, and a stable crystal structure is likely to be formed.

[0023] In the silicate phosphor having the composition represented by the formula (1), the variable x represents the molar ratio of the element M in 1 mol of the composition represented by the formula (1). 1 The silicate phosphor preferably has a variable x of more than 0 and 0.125 or less (0 < x ≦ 0.125), preferably in the range of 0.01 or more and 0.125 or less (0.01 ≦ x ≦ 0.125), more preferably in the range of 0.02 or more and 0.125 or less (0.02 ≦ x ≦ 0.125), and even more preferably in the range of 0.02 or more and 0.10 or less (0.02 ≦ x ≦ 0.10). If the variable x representing the molar ratio of the element M in 1 mol of the composition represented by the formula (1) of the silicate phosphor is in the range of more than 0 and 0.125 or less (0 < x ≦ 0.125), in order to achieve charge balance, the activating element Eu is divalent Eu 1 to trivalent Eu 2+ 3+ ​no longer needs to change, and divalent Eu that contributes to the luminescence in the silicate phosphor 2+ can be maintained, and the decrease in luminescence intensity can be reduced. Variable w representing the molar ratio with the second alkali element A 2 and variable x representing the molar ratio of element M 1 have a total of 1.0 or less (w + x ≤ 1.0).

[0024] In the silicate phosphor having the composition represented by the formula (1), variable y represents the molar ratio of Eu which is the activating element in 1 mol of the composition represented by the formula (1). In the silicate phosphor, in the composition represented by the formula (1), variable y is more than 0 and 0.08 or less (0 < y ≤ 0.08), preferably within the range of 0.01 or more and 0.08 or less (0.01 ≤ y ≤ 0.08), more preferably within the range of 0.02 or more and 0.07 or less (0.02 ≤ y ≤ 0.07), and even more preferably within the range of 0.03 or more and 0.06 or less (0.03 ≤ y ≤ 0.06). If the variable y representing the molar ratio of Eu in 1 mol of the composition represented by the formula (1) in the silicate phosphor is more than 0 and within the range of 0.08 or less (0 < y ≤ 0.08), a sufficient amount of Eu that contributes to luminescence is contained in the structure of the silicate phosphor.

[0025] In the silicate phosphor having the composition represented by the formula (1), for the stabilization of the crystal structure, the first alkali element A 1 contains Rb, and the second alkali element A 2 preferably contains Na. The large cubic structure centered on the first alkali element A 1 that enters between the silicate (SiO4) of the silicate phosphor and the tetrahedral structure composed of lithium oxide, and the cubic structure centered on the second alkali element A 2 The first alkali element A 1 which is the central element of the large cubic structure that enters between the aforementioned tetrahedral structures contains Rb, and the second alkali element A 2When Na is contained, the gaps in the tetrahedral structure and the large and small cubic structures are less likely to be distorted, and the crystal structure is stabilized. The silicate phosphor having the composition represented by the formula (1) contains the first alkali element A in order to stabilize the crystal structure. 1 is Rb, and the second alkali element A 2 More preferably, is Na.

[0026] In the silicate phosphor having the composition represented by the formula (1), the element M 1 In the silicate phosphor having the composition represented by the formula (1), the element M preferably contains Mg. 1 When Mg is included, the crystal structure of silicate phosphors is prone to defects, and the second alkali element A 2 Instead of 1 By replacing it with Eu, which is an activator element that contributes to luminescence, 2+ is trivalent Eu 3+ In the silicate phosphor having the composition represented by the formula (1), the element M 1 When Mg is included, divalent Mg is charged to the divalent Eu to achieve charge balance. 2+ Trivalent Eu 3+ and the second alkali element A 2 The crystal structure is easily stabilized by Mg, which has an ionic radius close to that of Mg, and defects in the crystal structure are suppressed, thereby maintaining the luminescence intensity. 1 In the silicate phosphor having the composition represented by the formula (1), the first alkali element A is more preferably Mg. 1 contains Rb, and the second alkali element A 2 When contains Na, element M 1 may contain Mg, and the element M 1 In the silicate phosphor having the composition represented by the formula (1), the first alkali element A may be Mg. 1 is Rb, and the second alkali element A 2is Na, the element M 1 may contain Mg, and the element M 1 may be Mg.

[0027] The thermoluminescence spectrum (glow curve) of the silicate phosphor having the composition represented by the formula (1) preferably has as low a thermoluminescence intensity (hereinafter also referred to as "TL intensity") as possible in the range of 550 K or higher in the thermoluminescence spectrum (glow curve) obtained by thermoluminescence measurement. The thermoluminescence spectrum (glow curve) of the phosphor obtained by thermoluminescence measurement shows that electrons trapped in defect levels due to defects in the crystal structure are the luminescence centers of Eu. 2+ The TL intensity is proportional to the concentration of the defect level. The source of electrons trapped in the defect level is Eu 3+ Eu can also exist as 2+ If the TL intensity in the range above 550 K in the thermoluminescence spectrum can be suppressed, the number of electrons trapped in the defect level can be reduced, and the decrease in emission intensity can be reduced.

[0028] In a silicate phosphor having a composition represented by formula (1), it is preferable that, in a thermoluminescence spectrum (glow curve) obtained by thermoluminescence measurement, the ratio TLa / TLp of the average TL intensity TLa in the range of 560 K to 580 K to the maximum TL intensity value TLp in the range of 240 K to 350 K is 0.25 or less. In a silicate phosphor having a composition represented by formula (1), if the ratio TLa / TLp of the average TL intensity TLa in the range of 560 K to 580 K to the maximum TL intensity value TLp in the range of 240 K to 350 K is 0.25 or less in the thermoluminescence spectrum (glow curve), the TL intensity in the range of 550 K or higher is suppressed, and a decrease in luminous intensity is reduced. In the thermoluminescence spectrum of a silicate phosphor having a composition represented by formula (1), the ratio TLa / TLp of the average TL intensity TLa in the range of 560 K or more and 580 K or less to the maximum TL intensity value TLp in the range of 240 K or more and 350 K or less is more preferably 0.20, even more preferably 0.15 or less, and even more preferably 0.10 or less.

[0029] The silicate phosphor having the composition represented by the formula (1) is excited by light in the wavelength range of 300 nm or more and 500 nm or less, and preferably emits fluorescence having a peak emission wavelength in the range of 520 nm or more and 560 nm or less, more preferably emits fluorescence having a peak emission wavelength in the range of 520 nm or more and 550 nm or less, and even more preferably emits fluorescence having a peak emission wavelength in the range of 520 nm or more and 540 nm or less.

[0030] The silicate phosphor may have an average particle size (Fisher Sub-Sieve Siezer's Number) measured by the Fisher Sub-Sieve Sizer (hereinafter referred to as the "FSSS method") in the range of 1 μm to 45 μm, or may have an average particle size in the range of 3 μm to 42 μm, or may have an average particle size in the range of 5 μm to 40 μm, or may have an average particle size in the range of 1 μm to 35 μm. A silicate phosphor having an average particle size measured by the FSSS method in the range of 1 μm to 45 μm exhibits excellent light-emitting properties and facilitates easy handling during the manufacture of light-emitting devices. The FSSS method is a method for measuring the specific surface area by utilizing the air flow resistance using an air permeability method, and primarily determines the particle size of primary particles.

[0031] The silicate phosphor may also be used in combination with phosphors that emit green, yellow, red, or deep red light, to produce a light-emitting device that produces white light by mixing the light emitted from the excitation light source and the light emitted from the phosphors.

[0032] The light emitting device includes the silicate phosphor described above and a light emitting element having an emission peak wavelength in the range of 300 nm to 500 nm and capable of irradiating the silicate phosphor with excitation light.

[0033] FIG. 1 is a schematic cross-sectional view showing an example of a light emitting device.

[0034] The light emitting device 100 includes a molded body 40 having a recess, a light emitting element 10 disposed in the recess of the molded body 40, and a wavelength conversion member 50 covering the light emitting element 10. The molded body 40 is formed by integrally molding a first lead 20, a second lead 30, and a resin portion containing a thermosetting resin, a thermoplastic resin, or an ultraviolet curable resin. The molded body 40 has the first lead 20 and the second lead 30 disposed so as to form the bottom surface of the recess, and the resin portion disposed so as to form the side surface of the recess. The light emitting element 10 is placed on the bottom surface of the recess of the molded body 40. 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, respectively. The light emitting element 10 is covered with a wavelength conversion member 50. The wavelength conversion member 50 includes a phosphor 70 containing a silicate phosphor that converts the wavelength of light emitted from the light emitting element 10, which serves as an excitation light source. The phosphor 70 may include a first phosphor 71 containing a silicate phosphor and a second phosphor 72 having a composition different from that of the first phosphor. The wavelength conversion member 50 functions not only as a wavelength conversion member but also as a member for protecting the light emitting element 10 and the phosphor 70 containing a silicate phosphor from the external environment. The light emitting device 100 emits light upon receiving a supply of power from an external source via the first lead 20 and the second lead 30.

[0035] A light-emitting element can be used as the excitation light source of the light-emitting device. The light-emitting element has an emission peak wavelength in the range of 300 nm to 500 nm, preferably 380 nm to 500 nm, more preferably 400 nm to 480 nm, even more preferably 420 nm to 470 nm, and particularly preferably 420 nm to 460 nm. By using a light-emitting element that emits light with an emission peak wavelength in the range of 300 nm to 500 nm as the excitation light source, a mixed color light of the light from the light-emitting element and the fluorescence from the phosphor is emitted.

[0036] The light-emitting element uses nitride semiconductors (In X Al Y Ga 1-X-YIt is preferable to use a semiconductor light-emitting element using a semiconductor light-emitting element having a wavelength of 0≦X, 0≦Y, X+Y≦1. By using a semiconductor light-emitting element as the excitation light source of a light-emitting device, it is possible to obtain a stable light-emitting device that is highly efficient, has high output linearity relative to input, and is resistant to mechanical shock. The full width at half maximum of the emission spectrum of the light-emitting element is preferably, for example, 30 nm or less.

[0037] The light emitting device includes the silicate phosphor described above. The silicate phosphor preferably has phosphor particles having a composition represented by formula (1) and emits fluorescence having a peak emission wavelength in the range of 520 nm to 560 nm when irradiated with excitation light having a peak emission wavelength in the range of 300 nm to 500 nm. The light emitting device may include a first phosphor containing the silicate phosphor and a second phosphor having a different composition from the silicate phosphor and emitting fluorescence having a peak emission wavelength different from that of the first phosphor. By including the silicate phosphor and a phosphor having a peak emission wavelength different from that of the silicate phosphor, the light emitting device can emit mixed-color light having a desired color temperature and exhibiting wide color reproducibility or high color rendering properties.

[0038] The first phosphor can be contained in a wavelength conversion member that covers the excitation light source to form a light emitting device. In a light emitting device in which a light emitting element that is an excitation light source is covered with a wavelength conversion member that contains the first phosphor, part of the light emitted from the light emitting element that is the excitation light source is absorbed by the first phosphor, and fluorescence having an emission peak wavelength at a wavelength different from the emission peak wavelength of the light emitted from the light emitting element is emitted.

[0039] The content of the first phosphor contained in the light-emitting device is not particularly limited. For example, the content of the first phosphor can be 1 part by mass or more and 200 parts by mass or less, and preferably 2 parts by mass or more and 180 parts by mass or less, per 100 parts by mass of the resin constituting the wavelength conversion member. The resin contained in the wavelength conversion member may be a thermosetting resin, a thermoplastic resin, or an ultraviolet-curable resin. Specific examples of the resin include acrylic resin, carbonate resin, sulfone resin, epoxy resin, urethane resin, ester resin, silicone resin, styrene resin, vinyl resin, olefin-based resin such as cyclic olefin resin, and (meth)acrylate-based resin, and the wavelength conversion member may contain at least one selected from the group consisting of these. In this specification, (meth)acrylate-based resin refers to a resin containing a (meth)acryloyl group, and refers to a resin containing at least one selected from the group consisting of methacrylate and acrylate. The resin may preferably contain at least one selected from the group consisting of acrylic resin, silicone resin, and epoxy resin. The resin contained in the wavelength conversion member may be a single type or a combination of two or more types.

[0040] In addition to the resin and phosphor, the wavelength conversion member may further contain a filler, a light diffusing material, etc. For example, by including a filler or a light diffusing material, the directionality of light from the excitation light source can be alleviated and the viewing angle can be increased. Examples of fillers and light diffusing materials include silica, titanium oxide, zinc oxide, zirconium oxide, and alumina. When the wavelength conversion member includes a filler or a light diffusing material, the content of the filler or light diffusing material can be, for example, 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the resin included in the wavelength conversion member.

[0041] The method for producing a silicate phosphor includes adding at least one first alkali element A selected from the group consisting of Rb and Cs. 1 and at least one second alkali element A selected from the group consisting of K, Na, and Li. 2 and at least one element M selected from the group consisting of Mg, Ca, Sr, Ba, Y, and La.1 A third compound containing, a fourth compound containing Li, a fifth compound containing Si, and a sixth compound containing Eu, wherein at least one of the compounds from the first compound to the sixth compound is an oxide, preparing a raw material; the first alkali element A contained in the first compound 1 the second alkali element A contained in the second compound 2 the element M contained in the third compound 1 Li contained in the fourth compound, Si contained in the fifth compound, and Eu contained in the sixth compound are mixed so as to satisfy the molar ratio in the composition represented by the following formula (1) to obtain a raw material mixture; the raw material mixture is heat-treated for the first time at a first temperature within the range of 400 °C or higher and 800 °C or lower in a reducing atmosphere to obtain a first heat-treated product having the composition represented by the following formula (1). A 1 1-w-x A 2 w M 1 x (Li3SiO4):Eu y (1) (In the formula (1), w, x, and y each satisfy 0 < w < 1.0, 0 < x ≤ 0.125, and 0 < y ≤ 0.08.)

[0042] The first compound to the sixth compound each contain the first alkali element A 1 the second alkali element A 2 the element M 1 Li, Si, and Eu, and oxides, hydroxides, carbonates can be used, and hydrates may also be used. Specifically, examples of the first compound containing the first alkali element A1 include Rb2O, RbOH, Rb2CO3, Cs2CO3, etc. The second alkali element A 2 Examples of the second compound containing include K2O, KOH, K2CO3, Na2O, NaOH, Na2CO3, Li2O, LiOH, Li2CO3, etc. The element M 1Examples of the third compound containing Li include MgO, Mg(OH)2, MgCO3, CaO, Ca(OH)2, CaCO3, SrO, Sr(OH)2, SrCO3, BaO, Ba(OH)2, BaCO3, Y2O3, Y2(CO3)3, La2O3, La(OH)3, etc. Examples of the fourth compound containing Li include Li2O, LiOH, Li2CO3, etc., similar to the second compound. Examples of the fifth compound containing Si include SiO2. Examples of the sixth compound containing Eu include Eu2O3, Eu(OH)2, EuCO3, etc. The second alkali element A 2 is Li, the second alkali element A 2 The second compound containing Li and the fourth compound containing Li may be the same compound. When the second compound and the fourth compound are the same compound containing Li, the molar ratio of Li contained in the compound is set to 1 / 2 mole of the second alkali element A in 1 mole of the composition represented by the formula (1). 2 The mole ratio of Li and the second alkali element A 2 It is preferable to mix the second compound and the fourth compound so as to satisfy the respective molar ratios of Li constituting the composition of (Li3SiO4) in the formula (1), rather than Li contained as

[0043] The first alkali element A contained in the first compound 1 , the second alkali element A contained in the second compound 2 , element M contained in the third compound 1 The elements Li contained in the fourth compound, Si contained in the fifth compound, and Eu contained in the sixth compound are weighed out so as to satisfy the molar ratio in the composition represented by the formula (1), and the first compound to the sixth compound are mixed to obtain a raw material mixture.

[0044] The weighed first to sixth compounds are mixed wet or dry using a mixer to obtain a raw material mixture. A commonly used industrial mill, such as a ball mill, vibration mill, roll mill, or jet mill, can be used as the mixer. The raw materials may be pulverized to increase their specific surface area so as to promote the reaction. The raw materials may be classified to ensure that the specific surface area of ​​each compound particle falls within a certain range. For classification of the raw materials, a commonly used industrial wet separator, such as a settling tank, hydrocyclone, or centrifuge, or a dry classifier, such as a cyclone or air separator, may be used.

[0045] The raw material mixture may contain a flux. The inclusion of a flux in the raw material mixture promotes the reactions of the first through sixth compounds during the first heat treatment of the raw material mixture, as described below, and the solid-phase reaction proceeds uniformly. This results in a first heat-treated product with large particle sizes and excellent luminescence properties. A halide can be used as the flux. When a halide is used as the flux, the temperature at which the liquid phase of the halide is generated and the temperature at which the raw material mixture is first heat-treated, as described below, are approximately equal. This allows the solid-phase reaction between the compounds to proceed more uniformly, resulting in a first heat-treated product with large particle sizes and excellent luminescence properties. Examples of halides used as fluxes include chlorides or fluorides containing rare earth metal elements such as cerium and europium, and chlorides or fluorides containing alkali or alkaline earth elements. When the elements contained in the flux are elements contained in the composition of the silicate phosphor, the molar ratio of the elements contained in the flux may be adjusted to achieve the composition of the desired silicate phosphor, and the flux may be added to the raw material mixture as part of the elements constituting the composition. Even if the element contained in the flux is an element contained in the composition of the silicate phosphor core particle, the flux may be further added to the raw material mixture without considering the composition of the silicate phosphor core particle. When the raw material mixture contains a flux, in order to further promote the reaction of the first compound to the sixth compound, the amount of the flux added is preferably 10 parts by mass or less, may be 5 parts by mass or less, or may be 1 part by mass or more, per 100 parts by mass of the raw material mixture not containing the flux.

[0046] The raw material mixture is subjected to a first heat treatment in a reducing atmosphere at a first temperature in the range of 400°C to 800°C to obtain a first heat-treated product having a composition represented by formula (1). The raw material mixture can be placed in a container such as a crucible or boat made of silicon carbide (SiC), quartz, aluminum oxide, boron nitride (BN), or the like, and subjected to the first heat treatment in a furnace.

[0047] The first temperature for the first heat treatment is in the range of 400° C. to 800° C., preferably in the range of 500° C. to 780° C., and more preferably in the range of 600° C. to 750° C. By performing the first heat treatment at a relatively low temperature in the range of 400° C. to 800° C., the first alkali element A 1 , second alkali element A 2 , the first alkali element A 1 or second alkali element A 2 Instead of a divalent or trivalent element M 1 A first heat-treated product can be obtained which is a silicate phosphor having a composition represented by formula (1) containing Eu and Cr.

[0048] The time for performing the first heat treatment is preferably 1 hour or more and 20 hours or less, more preferably 2 hours or more and 15 hours or less, and even more preferably 3 hours or more and 12 hours or less, in order to obtain a first heat-treated product which is a silicate phosphor having the composition represented by formula (1).

[0049] The atmosphere in which the first heat treatment is performed is a reducing atmosphere. The reducing atmosphere is preferably a nitrogen atmosphere containing reducing hydrogen gas. The nitrogen gas content in the nitrogen atmosphere containing reducing hydrogen gas is preferably 70% by volume or more, more preferably 80% by volume or more, and even more preferably 90% by volume or more. The hydrogen gas content in the nitrogen atmosphere containing reducing hydrogen gas is preferably 1% by volume or more, more preferably 5% by volume or more, and even more preferably 10% by volume or more. The atmosphere in which the first heat treatment is performed may be a reducing atmosphere using solid carbon in an air atmosphere. By firing the raw material mixture in a reducing atmosphere with high reducing power, divalent Eu in the first heat-treated product can be reduced. 2+ The content of divalent Eu can be increased. 2+ is oxidized to trivalent Eu 3+ However, by subjecting the raw material mixture to the first heat treatment in a reducing atmosphere with high reducing power, trivalent Eu contained in the first heat treatment product can be reduced. 3+ is divalent Eu 2+Therefore, the divalent Eu that contributes to luminescence is reduced to 2+ It is possible to obtain a first heat-treated product having an increased content of the element, and thus to obtain a first heat-treated product that is a silicate phosphor with high luminescence intensity.

[0050] The pressure when performing the first heat treatment may be standard atmospheric pressure (approximately 0.101 MPa), or may be a pressurized atmosphere of 0.101 MPa to 200 MPa in gauge pressure. By performing the first heat treatment in a pressurized atmosphere, decomposition of the crystal structure of the first heat treatment product is reduced, and a first heat treatment product can be obtained that becomes a silicate phosphor with reduced reduction in luminescence intensity. The pressure of the atmosphere when performing the first heat treatment is more preferably in the range of 0.101 MPa to 100 MPa in gauge pressure, even more preferably in the range of 0.5 MPa to 10 MPa, and from the viewpoint of ease of production, even more preferably in the range of 1.0 MPa to 10 MPa.

[0051] The obtained first heat-treated product may be subjected to post-treatments after the heat treatment, such as pulverization, dispersion, solid-liquid separation, and drying. Solid-liquid separation can be performed by an industrially commonly used method such as filtration, suction filtration, pressure filtration, centrifugation, and decantation. Drying can be performed by an industrially commonly used device such as a vacuum dryer, a hot air heating dryer, a conical dryer, or a rotary evaporator. After obtaining the first heat-treated product, post-treatment may be performed as needed, and the post-treated first heat-treated product may be converted into a silicate phosphor. After obtaining the first heat-treated product, post-treatment may be performed as needed, and the post-treated first heat-treated product may be subjected to a second heat treatment to obtain a second heat-treated product.

[0052] In the method for producing a silicate phosphor, the obtained first heat-treated product is preferably subjected to a second heat treatment at a second temperature within the range of 200°C or more and 350°C or less to obtain a second heat-treated product having a composition represented by formula (1).

[0053] The second temperature at which the second heat treatment is performed is preferably in the range of 200°C to 350°C, and more preferably in the range of 200°C to 300°C. By performing the second heat treatment at a relatively low second temperature that is about half the first temperature of the first heat treatment, the crystal structure is stabilized, and a second heat-treated product that becomes a silicate phosphor with high luminescence intensity can be obtained. By performing the second heat treatment at a low temperature of 200°C to 350°C, the first alkali element A that is inserted between the four-coordinate tetrahedral structure of the silicate phosphor composed of silicate (SiO4) and lithium oxide can be obtained. 1 A large cubic structure with the second alkali element A at the center 2 The cubic structure centered on the first alkali element, A 1 or second alkali element A 2 Element M to be replaced by 1 It is presumed that this stabilizes the structure and makes distortion less likely to occur.

[0054] The second heat treatment may be performed in an atmosphere containing oxygen, nitrogen, or a rare gas. The atmosphere in which the second heat treatment is performed may be air (oxygen content of 20% by volume or more), nitrogen (100% by volume nitrogen), or a rare gas (e.g., 100% by volume argon (Ar)).

[0055] The time for which the second heat treatment is performed may be, for example, from 0.5 hours to 20 hours, from 1 hour to 15 hours, or from 2 hours to 12 hours. By setting the holding time to from 0.5 hours to 20 hours, the crystal structure can be further stabilized.

[0056] The pressure of the atmosphere in which the second heat treatment is performed may be standard atmospheric pressure (approximately 0.101 MPa), or may be 0.101 MPa or higher, or may be a pressurized atmosphere of 0.101 MPa to 100 MPa. By performing the second heat treatment in a pressurized atmosphere of 0.101 MPa to 100 MPa, the crystal structure can be stabilized. The pressure of the atmosphere in which the second heat treatment is performed, in terms of gauge pressure, is more preferably in the range of 0.101 MPa to 100 MPa, even more preferably in the range of 0.5 MPa to 10 MPa, and from the viewpoint of ease of production, even more preferably in the range of 1.0 MPa to 10 MPa. [Example]

[0057] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0058] The following evaluations were made for each silicate phosphor in the Examples and Comparative Examples described later. The evaluations are shown in Tables 1 and 2 together with the molar ratios of the charged compositions of each silicate phosphor in the Examples and Comparative Examples described later. In Table 1, the symbol "-" indicates that there is no numerical value for the corresponding item. Each silicate phosphor in Examples 1 to 11 described later has a composition represented by the formula (1) above.

[0059] Emission characteristics (relative emission intensity, emission peak wavelength λp, full width at half maximum (FWHM)) For each silicate phosphor according to the examples and comparative examples, excitation light having an emission peak wavelength of 450 nm was irradiated onto each phosphor using a spectrofluorometer (Hitachi High-Tech Science Corporation, F-4500), and the emission spectrum was measured at room temperature (25°C ± 5°C). The emission peak wavelength λp (nm), full width at half maximum (FWHM) (nm), and emission intensity at the emission peak wavelength in the emission spectrum of each phosphor were measured. 6―z Al z O z N 8-z :EU y1(y1 and z satisfy 0 < y1 ≤ 1.0 and 0 < z ≤ 4.2.) With the emission intensity at the emission peak wavelength of the β-sialon phosphor having the composition represented as 100%, the emission intensity of each silicate phosphor was expressed as the relative emission intensity. FIG. 2 shows the emission spectra of the silicate phosphors according to Examples 1 to 4 and the silicate phosphor according to Comparative Example 1. FIG. 3 shows the emission spectra of the silicate phosphor according to Example 7 and the silicate phosphor according to Comparative Example 2.

[0060] Samples for light resistance evaluation To 100 parts by mass of an acrylic resin, 50 parts by mass of each silicate phosphor of the examples and comparative examples were mixed to prepare a resin composition. The resin composition was formed into a sheet, and a barrier film having a thickness of 100 μm and a water vapor transmission rate of 0.02 g / m 2 ·day at a temperature of 40 ° C and a relative humidity of 90% was placed above and below the sheet of the resin composition to sandwich the sheet. The sheet was irradiated with ultraviolet light at room temperature to ultraviolet-cure the resin of the sheet, and a sheet-like wavelength conversion member having a thickness of 70 μm containing each silicate phosphor of the examples and comparative examples was obtained and used as a sample for light resistance evaluation. The wavelength conversion member is sandwiched between two barrier films, and the total thickness of the two barrier films and the wavelength conversion member is 270 μm.

[0061] 2]Light resistance evaluation For each of the obtained samples, at room temperature (25 ° C), the emission peak wavelength was 450 nm, and 36 mW / cm 2 Each sample was placed on the side irradiated with the light of a light-emitting element (LED) that irradiates excitation light with an output of, and the sample was irradiated with the excitation light from the light-emitting element for 500 hours. After 500 hours elapsed, the emission spectrum of each sample was measured, and the emission intensity at the emission peak wavelength was measured. Before 500 hours elapsed, the emission spectrum of each sample when irradiated with the excitation light from the light-emitting element was measured, and the ratio of the emission intensity at the emission peak wavelength after irradiating the excitation light for 500 hours to 100% of the emission intensity at the emission peak wavelength of each sample before 500 hours elapsed was expressed as the emission maintenance rate (%). FIG. 4 shows a graph of the relationship between the irradiation time of the excitation light and the emission maintenance rate of the silicate phosphors according to Examples 2 and 7 and the silicate phosphor according to Comparative Example 1.

[0062] Example 1 First alkali element A 1 The first compound containing Rb2CO3, the second alkali element A 2 The second compound containing Na is Na2CO3, and the element M 1 The raw materials for the first to sixth compounds are prepared: MgO as the third compound containing Li, Li2CO3 as the fourth compound containing Li, SiO2 as the fifth compound containing Si, and Eu2O3 as the sixth compound containing Eu. The first to sixth compounds were weighed and mixed to obtain a raw material mixture such that the molar ratio of each element in the raw material mixture, Rb:Na:Mg:Li:Si:Eu, was 0.75:0.23:0.02:3:1:0.04. The molar ratio of each element contained in the first to sixth compounds in the raw material mixture satisfies the molar ratio that results in the composition expressed by formula (1). The raw material mixture is filled into a container made of aluminum oxide and subjected to a first heat treatment in a reducing atmosphere of a nitrogen and hydrogen gas mixture (nitrogen:hydrogen volume ratio 70:30) at a first heat treatment temperature of 750°C for 10 hours to obtain a first heat-treated product, which is then subjected to post-treatments such as pulverization, dispersion, solid-liquid separation, and drying. The first heat-treated product and alumina balls were placed in a solvent (ethanol) and wet-pulverized. 100 parts by mass of the pulverized first heat-treated product were placed in 440 parts by mass of ethanol, and while stirring with a stirrer, 100 parts by mass of a 7% by mass aqueous hydrochloric acid solution was added dropwise over 30 minutes. After the hydrochloric acid solution was added dropwise, the mixture of the first heat-treated product, ethanol, and aqueous hydrochloric acid solution was stirred for 30 minutes to disperse the mixture. The first heat-treated product was then subjected to solid-liquid separation, washed with ethanol, and dried in a nitrogen atmosphere (N2:100% by volume) at 25°C for two days. A first heat-treated product was obtained that had undergone post-treatments of pulverization, dispersion, solid-liquid separation, and drying. The resulting first heat-treated product was designated the silicate phosphor of Example 1.

[0063] Example 2 The same compounds as in Example 1 were used as in Example 1, and the first to sixth compounds were weighed and mixed so that the molar ratio of the charged composition of each element was Rb:Na:Mg:Li:Si:Eu = 0.75:0.21:0.04:3:1:0.04 to obtain a raw material mixture. The same procedure was followed as in Example 1, except that a first heat-treated product was used, and the resulting first heat-treated product was designated as the silicate phosphor of Example 2.

[0064] Example 3 The same compounds as in Example 1 were used as in Example 1, and the first to sixth compounds were weighed and mixed so that the molar ratio of the charged composition of each element was Rb:Na:Mg:Li:Si:Eu = 0.75:0.17:0.08:3:1:0.04. Except for this, a raw material mixture was obtained in the same manner as in Example 1, and the resulting first heat-treated product was used as the silicate phosphor of Example 3.

[0065] Example 4 The same compounds as in Example 1, 1 to 6, were used, and the raw material mixture was obtained by weighing and mixing the compounds so that the molar ratio of the charged composition of each element was Rb:Na:Mg:Li:Si:Eu = 0.75:0.125:0.125:3:1:0.04. The same procedure as in Example 1 was used, except that the raw material mixture obtained was obtained by weighing and mixing the compounds so that the molar ratio of the charged composition of each element was Rb:Na:Mg:Li:Si:Eu = 0.75:0.125:0.125:3:1:0.04. The first heat-treated product was used as the silicate phosphor of Example 4.

[0066] Comparative Example 1 element M 1 The first heat-treated product obtained in the same manner as in Example 1 is designated as the silicate phosphor of Comparative Example 1, except that the third compound containing Rb is not used, and the first, second, and fourth to sixth compounds similar to those in Example 1 are used, and the first, second, and fourth to sixth compounds are weighed and mixed so that the molar ratio of the charged composition of each element is Rb:Na:Mg:Li:Si:Eu=0.75:0.25:0:3:1:0.04.

[0067] [Table 1]

[0068] When irradiated with excitation light from a light-emitting element having an emission peak wavelength of 450 nm, the silicate phosphors according to Examples 1 to 4 emit green fluorescence having an emission peak wavelength λp of 530 nm in the range of 520 nm to 560 nm. The silicate phosphors according to Examples 1 to 4 have sharper emission peaks in their emission spectra with narrower full widths at half maximum than a β-sialon phosphor that emits green fluorescence having an emission peak wavelength of 529 nm. As shown in Figure 2, the silicate phosphors according to Examples 1 to 3 have emission peaks that nearly overlap in their emission spectra.

[0069] The silicate phosphors according to Examples 1 to 4 contain the element M in the composition represented by the formula (1). 1 Contains the first alkali element A 1 or second alkali element A 2 A part of the divalent element M 1 The silicate phosphors according to Examples 1 to 4 have a composition in which divalent Eu, which contributes to light emission, is replaced by Mg, in order to achieve charge balance. 2+ is trivalent Eu 3+ The change in power consumption can be reduced to 36mW / cm 2 Even after 500 hours of continuous irradiation with excitation light of output power of 1000 kJ / s, the luminescence maintenance rate was over 60%, and the decrease in luminescence intensity was reduced.

[0070] The silicate phosphor according to Comparative Example 1 contains the element M in its composition. 1 Since the silicate phosphor according to Comparative Example 1 does not contain the element M, the relative luminescence intensity is slightly higher than that of the silicate phosphors according to Examples 1 to 4. On the other hand, the silicate phosphor according to Comparative Example 1 does not contain the element M in its composition. 1 Since it does not contain divalent Eu, which contributes to luminescence, 2+ is trivalent Eu 3+ The change in the power consumption cannot be reduced to 36 mW / cm 2 When the excitation light of this output is continuously irradiated for 500 hours, the luminescence maintenance rate drops to less than 60%.

[0071] Example 5 element M 1 The first, second, and fourth to sixth compounds were the same as in Example 1, except that CaCO3 was used as the third compound containing Rb:Na:Ca:Li:Si:Eu, and the first to sixth compounds were weighed and mixed so that the molar ratio of the charged composition of each element was Rb:Na:Ca:Li:Si:Eu=0.75:0.23:0.02:3:1:0.04. A first heat-treated product was obtained in the same manner as in Example 1, except that a raw material mixture was used, and the resulting first heat-treated product was designated as the silicate phosphor of Example 5.

[0072] Example 6 element M 1 The first, second, and fourth to sixth compounds were the same as in Example 1, except that La2O3 was used as the third compound containing Rb:Na:La:Li:Si:Eu, and the first to sixth compounds were weighed and mixed so that the molar ratio of the charged composition of each element was Rb:Na:La:Li:Si:Eu=0.75:0.23:0.02:3:1:0.04. A first heat-treated product was obtained in the same manner as in Example 1, except that a raw material mixture was used, and the resulting first heat-treated product was designated as the silicate phosphor of Example 6.

[0073] Example 7 The same first to sixth compounds as in Example 1 are weighed and mixed so that the molar ratio of the charged composition of each element is Rb:Na:Mg:Li:Si:Eu = 0.75:0.21:0.04:3:1:0.04, and a raw material mixture is obtained using the same process as in Example 1. The obtained first heat-treated product is subjected to a second heat treatment at 300°C for 10 hours in a nitrogen atmosphere (N2:100% by volume) to obtain a second heat-treated product, which is used as the silicate phosphor of Example 7.

[0074] Example 8 The same first to sixth compounds as in Example 1 are weighed and mixed so that the molar ratio of the charged composition of each element is Rb:Na:Mg:Li:Si:Eu = 0.75:0.21:0.04:3:1:0.04, and a raw material mixture is obtained using the same process as in Example 1. The obtained first heat-treated product is subjected to a second heat treatment at 250°C for 10 hours in a nitrogen atmosphere (N2:100% by volume) to obtain a second heat-treated product, which is used as the silicate phosphor of Example 8.

[0075] Example 9 The same compounds as in Example 1, the first compound to the sixth compound, were weighed and mixed so that the molar ratio of the charged elements was Rb:Na:Mg:Li:Si:Eu = 0.75:0.21:0.04:3:1:0.04, and a raw material mixture was obtained using the same process as in Example 1. The obtained first heat-treated product was subjected to a second heat treatment at 200°C for 10 hours in a nitrogen atmosphere (N2:100% by volume) to obtain a second heat-treated product, which was used as the silicate phosphor of Example 9.

[0076] Example 10 The same compounds as in Example 1, the first compound to the sixth compound, were weighed and mixed so that the molar ratio of the charged elements was Rb:Na:Mg:Li:Si:Eu = 0.75:0.17:0.08:3:1:0.02, and a raw material mixture was obtained using the same process as in Example 1. The obtained first heat-treated product was subjected to a second heat treatment at 250°C for 10 hours in a nitrogen atmosphere (N2:100% by volume) to obtain a second heat-treated product, which was designated as the silicate phosphor of Example 10.

[0077] Example 11 The same first to sixth compounds as in Example 1 are weighed and mixed so that the molar ratio of the charged elements is Rb:Na:Mg:Li:Si:Eu = 0.75:0.17:0.08:3:1:0.01, and a raw material mixture is obtained using the same process as in Example 1. The obtained first heat-treated product is subjected to a second heat treatment at 250°C for 10 hours in a nitrogen atmosphere (N2:100% by volume) to obtain a second heat-treated product, which is designated as the silicate phosphor of Example 11.

[0078] Comparative Example 2 The first heat-treated product obtained in Comparative Example 1 is subjected to a second heat treatment at 150° C. for 10 hours in a nitrogen atmosphere (N2: 100% by volume), and this second heat-treated product is used as the silicate phosphor of Comparative Example 2.

[0079] [Table 2]

[0080] The silicate phosphors according to Examples 5 to 11 emit green fluorescence having an emission peak wavelength λp of 527 nm to 530 nm in the range of 520 nm to 560 nm when irradiated with excitation light from a light-emitting element having an emission peak wavelength of 450 nm. Even after the second heat treatment, the silicate phosphors according to Examples 5 to 11 have a sharp emission peak with a narrower full width at half maximum in the emission spectrum than the β-sialon phosphor that emits green fluorescence having an emission peak wavelength of 529 nm listed in Table 1. The silicate phosphors according to the examples can achieve a wider range of color reproducibility when used in a light-emitting device for backlight.

[0081] As shown in FIG. 3, the silicate phosphor of Example 7 obtained by the second heat treatment has an emission peak wavelength in the range of 520 nm to 560 nm when irradiated with excitation light from a light-emitting element having an emission peak wavelength of 450 nm.

[0082] The silicate phosphors according to Examples 5 to 11 each contain an element M in the composition represented by the formula (1).1 Contains the first alkali element A 1 or second alkali element A 2 A part of the element M is divalent or trivalent 1 The silicate phosphors according to Examples 5 to 11 have a composition in which divalent Eu, which contributes to light emission, is replaced with 2+ is trivalent Eu 3+ The change in power consumption can be reduced to 36mW / cm 2 Even after 500 hours of continuous irradiation with excitation light of an output of 36 mW / cm, the luminescence maintenance rate exceeded 60%, and the decrease in luminescence intensity was reduced. The silicate phosphors according to Examples 7 to 11 were subjected to a second heat treatment at a temperature of 200°C or higher and 350°C or lower, and therefore had an luminescence maintenance rate of 36 mW / cm. 2 The silicate phosphors according to Examples 7 to 11 have an emission maintenance rate of more than 90% even after being irradiated with excitation light of an output of 1000 W for 500 hours, and are therefore very light-resistant. 1 or second alkali element A 2 A part of the element M is divalent or trivalent 1 The crystal structure of the silicate phosphor replaced by Eu becomes more stable, and the divalent Eu contributes to the emission. 2+ is trivalent Eu 3+ It is presumed that the change in the emission intensity can be further reduced, the decrease in the emission intensity is further reduced, and the silicate phosphors according to Examples 10 and 11 have a high emission maintenance rate. In the composition represented by the formula (1), the silicate phosphors according to Examples 10 and 11 have a lower molar ratio of Eu as an activator element compared to the silicate phosphor according to Example 3 shown in Table 1 above, but still have an emission maintenance rate of more than 90% and are more excellent in light resistance.

[0083] The silicate phosphor according to Comparative Example 2 contains the element M in its composition. 1 The temperature of the second heat treatment is 150°C, which is low at less than 200°C, so that the divalent Eu that contributes to luminescence is not contained. 2+ is trivalent Eu 3+ The change in the power consumption cannot be reduced to 36 mW / cm 2After 500 hours of irradiation with excitation light of output of 1000 kJ / s, the luminescence maintenance rate drops to 34.4%.

[0084] 4 is a graph showing the relationship between the irradiation time of excitation light and the luminescence maintenance rate of each of the silicate phosphors according to Examples 2 and 7 and the silicate phosphor according to Comparative Example 1. As shown in FIG. 4, each of the silicate phosphors according to Examples 2 and 7 contains the element M in the composition represented by the formula (1). 1 Contains the first alkali element A 1 or second alkali element A 2 A part of the element M is divalent or trivalent 1 In order to achieve charge balance, divalent Eu, which contributes to luminescence, is replaced by 2+ is trivalent Eu 3+ The silicate phosphor of Example 7, which was subjected to the second heat treatment, exhibited a very high luminescence maintenance rate of 98% or more even after being continuously irradiated with excitation light for 500 hours, and was therefore excellent in light resistance.

[0085] Thermoluminescence spectra were measured as follows for each of the silicate phosphors according to Examples 3 and 7, and the silicate phosphor according to Comparative Example 1. Table 3 shows the ratio TLa / TLp of the average thermoluminescence intensity TLa within the range of 560 K or more and 580 K or less to the maximum thermoluminescence intensity value TLp within the range of 240 K or more and 350 K or less in the thermoluminescence spectra obtained by measuring the thermoluminescence intensity of the silicate phosphors according to Examples 3 and 7, and the silicate phosphor according to Comparative Example 1.

[0086] Thermoluminescence Spectrum For each silicate phosphor according to the Examples and Comparative Examples, an excitation light source using a xenon lamp with a bandpass filter (313 nm, half-width 40 nm) was used as a light source at a temperature of 200 K for 5 minutes. The excitation light was then blocked, and a photomultiplier tube with a bandpass filter (550 nm, half-width 40 nm) was used as a detector. The change in emission intensity was recorded as the temperature was increased, and the thermoluminescence spectrum was measured. To release previously trapped electrons, the samples were heated to 600 K before measurement, and then measurements were performed at a heating rate of 30 K / min. Figure 5 shows the thermoluminescence spectra of the silicate phosphors according to Examples 3 and 7 and Comparative Example 1, measured at a temperature increase rate of 30 K / min.

[0087] [Table 3]

[0088] In the thermoluminescence spectrum (glow curve) obtained by thermoluminescence measurement of each silicate phosphor according to Examples 3 and 7, the ratio TLa / TLp of the average TL intensity TLa in the range of 560K to 580K to the maximum TL intensity value TLp in the range of 240K to 350K is 0.25 or less, the TL intensity in the range of 550K or more is suppressed, the luminescence maintenance rate after continued irradiation with excitation light is high at over 60%, and the decrease in luminescence intensity is reduced.

[0089] As shown in FIG. 5, in the thermoluminescence spectrum (glow curve) of each of the silicate phosphors according to Examples 3 and 7, the TL intensity is reduced in the range of 550 K or higher in the thermoluminescence measurement. This indicates that the silicate phosphors have few defects in the crystal structure that trap electrons, and electrons are less likely to be trapped in the defect levels. 2+ electrons are not easily supplied to Eu 3+ Since the wavelength is not easily changed, even if the excitation light is continuously irradiated, the decrease in the emission intensity is reduced.

[0090] The silicate phosphor according to Comparative Example 1 contains the element M in its composition. 1Since the silicate phosphor of Comparative Example 1 does not contain , in the thermoluminescence spectrum (glow curve) obtained by thermoluminescence measurement, the ratio TLa / TLp of the average TL intensity TLa in the range of 560 K or more and 580 K or less to the maximum TL intensity value TLp in the range of 240 K or more and 350 K or less is greater than 0.25 and becomes 1.08. Since the silicate phosphor of Comparative Example 1 has a high TL intensity in the range of 550 K or more, the luminescence maintenance rate after continued irradiation with excitation light is less than 60%, and the luminescence intensity is low.

[0091] As shown in FIG. 5, in the thermoluminescence spectrum (glow curve) of each silicate phosphor according to Comparative Example 1, the TL intensity in the range of 550 K or higher becomes extremely high from 520 K or higher, indicating that there are many defects in the crystal structure that trap electrons, and the electrons trapped in the defect levels are trapped in Eu 2+ donates electrons to Eu 3+ Therefore, the emission intensity decreases when the excitation light is continuously irradiated.

[0092] The X-ray diffraction patterns of the silicate phosphors according to Examples 1 to 11 and Comparative Examples 1 and 2 were measured as follows. Figure 6 shows the X-ray diffraction patterns of the silicate phosphors according to the Examples and Comparative Examples. Figure 7 shows the X-ray diffraction patterns of the silicate phosphors according to Examples 1 to 4, enlarging the area where the diffraction angle 2θ (°) is from 37° to 37.8°.

[0093] X-ray diffraction pattern For each silicate phosphor according to the examples and comparative examples, the X-ray diffraction pattern was measured using a horizontal sample multipurpose X-ray diffractometer (Ultima IV, manufactured by Rigaku Corporation) and an X-ray source: CuKα radiation (λ=1.5418 Å, tube voltage 40 kV, tube current 40 mA).

[0094] In the X-ray diffraction patterns shown in FIG. 6, the silicate phosphors according to Examples 1 to 11 and the silicate phosphors according to Comparative Examples 1 and 2 have peaks at almost the same diffraction angle 2θ (°), and in the composition represented by the formula (1), 1or the second alkali element A 2 Even if part of 2 is replaced with a divalent or trivalent element M 1 the crystal structure does not change significantly.

[0095] In the partially enlarged X-ray diffraction pattern shown in FIG. 7, for the silicate phosphors according to Examples 1 to 4, as the molar ratio of the element M 1 in the preparation composition increases, a minute peak can be confirmed at the position where the diffraction angle 2θ (°) is 37.4°. In the silicate phosphor having the composition represented by the formula (1), it is presumed that 1 the crystal structure changes slightly as the molar ratio of the element M increases.

[0096] Embodiments according to the present disclosure include the following silicate phosphors, light-emitting devices, and methods for manufacturing silicate phosphors. [Item 1] A silicate phosphor having a composition represented by the following formula (1). A 1 1-w-x A 2 w M 1 x (Li3SiO4):Eu y (1) (In the formula (1), A 1 is at least one first alkali element selected from the group consisting of Rb and Cs, A 2 is at least one second alkali element selected from the group consisting of K, Na, and Li, M 1 is at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Y, and La, and w, x, and y each satisfy 0 < w < 1.0, 0 < x ≤ 0.125, w + x ≤ 1.0, and 0 < y ≤ 0.08.) [Item 2] The silicate phosphor according to Item 1, wherein in the formula (1), w, x, and y satisfy 0.1 ≤ w ≤ 0.24, 0.01 ≤ x ≤ 0.125, and 0.01 ≤ y ≤ 0.08. [Item 3] The silicate phosphor according to Item 1 or 2, wherein in the formula (1), x satisfies 0.02 ≤ x ≤ 0.125. [Item 4] In the formula (1), A 1 contains Rb, and A 2 Item 4. The silicate phosphor according to any one of items 1 to 3, wherein contains Na. [Section 5] In the formula (1), A 1 is Rb and A 2 4. The silicate phosphor according to claim 1, wherein is Na. [Section 6] In the above formula (1), M 1 Item 6. The silicate phosphor according to any one of items 1 to 5, wherein Mg is contained. [Section 7] In the above formula (1), M 1 6. The silicate phosphor of claim 1, wherein is Mg. [Section 8] Item 8. The silicate phosphor according to any one of Items 1 to 7, wherein in a thermoluminescence spectrum obtained by measuring thermoluminescence intensity, the ratio TLa / TLp of the maximum thermoluminescence intensity value TLp within the range of 240 K to 350 K and the average thermoluminescence intensity TLa within the range of 560 K to 580 K is less than 0.25. [Section 9] A light-emitting device comprising: the silicate phosphor according to any one of claims 1 to 8; and a light-emitting element having an emission peak wavelength in the range of 300 nm to 500 nm, which irradiates the silicate phosphor with excitation light. [Section 10] At least one first alkali element A selected from the group consisting of Rb and Cs 1 and at least one second alkali element A selected from the group consisting of K, Na, and Li. 2 and at least one element M selected from the group consisting of Mg, Ca, Sr, Ba, Y, and La. 1 preparing a raw material including a third compound containing Li, a fourth compound containing Li, a fifth compound containing Si, and a sixth compound containing Eu, wherein at least one compound among the first compound to the sixth compound is an oxide; a first alkali element A contained in the first compound;1 and the second alkali element A contained in the second compound 2 and the element M contained in the third compound 1 mixing Li contained in the fourth compound, Si contained in the fifth compound, and Eu contained in the sixth compound so as to satisfy the molar ratios in the composition represented by the following formula (1) to obtain a raw material mixture performing a first heat treatment on the raw material mixture at a first temperature within a range of 400°C or higher and 800°C or lower in a reducing atmosphere to obtain a first heat-treated product having a composition represented by the following formula (1), a method for producing a silicate phosphor. A 1 1-w-x A 2 w M 1 x (Li3SiO4):Eu y (1) (In the formula (1), w, x, and y each satisfy 0 < w < 1.0, 0 < x ≤ 0.125, w + x ≤ 1.0, and 0 < y ≤ 0.08.) [Item 11] performing a second heat treatment on the first heat-treated product at a second temperature within a range of 200°C or higher and 350°C or lower to obtain a second heat-treated product having a composition represented by the formula (1), the method for producing a silicate phosphor according to Item 10.

Industrial Applicability

[0097] The silicate phosphor of the present disclosure can be used as a phosphor contained in a wavelength conversion member of a light-emitting device, and a light-emitting device including the silicate phosphor can be suitably used for light-emitting devices applied to illumination light sources, LED displays, backlight light sources for liquid crystals, traffic signals, illuminated switches, light sources for projectors, various sensors, various indicators, and the like.

Explanation of Signs

[0098] 10: Light-emitting element, 20: First lead, 30: Second lead, 40: Molded body, 50: Wavelength conversion member, 70: Phosphor, 71: First phosphor, 72: Second phosphor, 100: Light-emitting device.

Claims

1. A silicate phosphor having a composition represented by the following formula (1): A １ １－ｗ－ｘ A ２ ｗ M １ ｘ (Li ３ 2000 ４ ):Eu ｙ (1) (In the formula (1), A １ is at least one first alkali element selected from the group consisting of Rb and Cs, and A ２ is at least one second alkali element selected from the group consisting of K, Na, and Li, and M １ is at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Y, and La, and w, x, and y respectively satisfy 0<w<1.0, 0<x≦0.125, w+x≦1.0, and 0<y≦0.

08.

2. 2. The silicate phosphor according to claim 1, wherein in formula (1), w, x, and y satisfy 0.1≦w≦0.24, 0.01≦x≦0.125, and 0.01≦y≦0.

08.

3. 2. The silicate phosphor according to claim 1, wherein in formula (1), x satisfies 0.02≦x≦0.

125.

4. In the formula (1), A １ contains Rb, and A ２ The silicate phosphor of claim 1 , wherein comprises Na.

5. In the formula (1), A １ is Rb, and A ２ The silicate phosphor of claim 1 , wherein is Na.

6. In the formula (1), M １ The silicate phosphor of claim 1 , wherein comprises Mg.

7. In the formula (1), M １ 2. The silicate phosphor of claim 1, wherein is Mg.

8. 2. The silicate phosphor according to claim 1, wherein in a thermoluminescence spectrum obtained by measuring thermoluminescence intensity, the ratio TLa / TLp of the average thermoluminescence intensity TLa within the range of 560 K or more and 580 K or less to the maximum thermoluminescence intensity value TLp within the range of 240 K or more and 350 K or less is less than 0.

25.

9. A light-emitting device comprising: the silicate phosphor according to any one of claims 1 to 8; and a light-emitting element having an emission peak wavelength in the range of 300 nm to 500 nm, which irradiates the silicate phosphor with excitation light.

10. At least one first alkali element A selected from the group consisting of Rb and Cs １ and at least one second alkali element A selected from the group consisting of K, Na, and Li. ２ and at least one element M selected from the group consisting of Mg, Ca, Sr, Ba, Y, and La. １ preparing a raw material including a third compound containing Li, a fourth compound containing Li, a fifth compound containing Si, and a sixth compound containing Eu, wherein at least one compound among the first compound to the sixth compound is an oxide; The first alkali element A contained in the first compound １ , the second alkali element A contained in the second compound ２ , the element M contained in the third compound １ Li contained in the fourth compound, Si contained in the fifth compound, and Eu contained in the sixth compound are mixed so as to satisfy a molar ratio in a composition represented by the following formula (1), thereby obtaining a raw material mixture; and subjecting the raw material mixture to a first heat treatment in a reducing atmosphere at a first temperature in the range of 400°C or higher and 800°C or lower to obtain a first heat-treated product having a composition represented by formula (1): A １ １－ｗ－ｘ A ２ ｗ M １ ｘ (Li ３ 2000 ４ ):Eu ｙ (1) (In the formula (1), w, x, and y satisfy the following conditions: 0<w<1.0, 0<x≦0.125, w+x≦1.0, and 0<y≦0.08, respectively.)

11. 11. The method for producing a silicate phosphor according to claim 10, comprising: subjecting the first heat-treated product to a second heat treatment at a second temperature within a range of 200°C or higher and 350°C or lower to obtain a second heat-treated product having a composition represented by formula (1).

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