TW202104549A - Surface-coated phosphor particle, method for producing surface-coated phosphor particle, and light emitting device - Google Patents

Abstract

A surface-coated phosphor particle of the present invention includes a particle containing a phosphor and a coating portion that coats the surface of the particle, wherein the phosphor has a composition represented by the general formula M¹ _a M² _b M³ _c Al₃ N_4-d O_d (wherein M¹ is one or more elements selected from the group consisting of Sr, Mg, Ca, and Ba, M² is one or more elements selected from the group consisting of Li and Na, and M³ is one or more elements selected from the group consisting of Eu and Ce), in which the values for a, b, c, and d satisfy each of the following formulas: 0.850≤a≤1.150, 0.850≤b≤1.150, 0.001≤c≤0.015, 0≤d≤0.40, 0≤d/(a+d)＜0.30, and the coating portion forms at least part of the outermost surface of the particle and contains a fluorine-containing compound containing elemental fluorine and elemental aluminum such that the elemental fluorine content is at least 15% by mass but not more than 30% by mass of the entire surface-coated phosphor particle.

Description

Surface-coated phosphor particles, method for manufacturing surface-coated phosphor particles, and light-emitting device

The present invention relates to surface-coated phosphor particles, a method for manufacturing surface-coated phosphor particles, and a light-emitting device.

Light-emitting devices formed by combining light-emitting diodes (LEDs) and phosphors have been widely used in lighting devices or backlights of liquid crystal display devices. Especially when the liquid crystal display device uses a light emitting device, there is a demand for high color reproducibility, so it is desirable to use a phosphor with a narrow full width at half maximum (hereinafter referred to as "half width") of the fluorescent spectrum.

As the conventionally used red phosphor with a narrow half-value width, a nitride phosphor or an oxynitride phosphor activated ^{by Eu 2+ is known.} For their representative pure nitride phosphors, there are Sr ₂ Si ₅ N ₈ : Eu ²⁺ , CaAlSiN ₃ : Eu ²⁺ (referred to as CASN), (Ca, Sr)AlSiN ₃ : Eu ²⁺ (Referred to as SCASN) and so on. CASN phosphors and SCASN phosphors have peak wavelengths in the range of 610 to 680 nm, and their half-value widths are narrower than 75 nm and less than 90 nm. However, when these phosphors are used as light-emitting devices for liquid crystal displays, there is a demand for a wider color reproduction range and a demand for phosphors with a narrower half-value width.

_{In recent years, SrLiAl 3} N ₄ :Eu ²⁺ (abbreviated as SLAN) phosphors are known for displaying red phosphors with a half-value width of less than 70nm in the narrow band region. Light-emitting devices using this phosphor can be Expect excellent color rendering or color reproducibility.

Patent Document 1 discloses a SLAN phosphor having a specific composition. [Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Application Publication No. 2017-088881

[The problem to be solved by the invention]

SLAN phosphor has the property of being easily decomposed when it comes in contact with water. This property becomes the main reason why the luminous intensity decreases with the passage of time. In recent years, the reliability of light-emitting devices using SLAN phosphors needs to be further improved, and the moisture resistance of SLAN phosphors also needs to be further improved. [Means to solve the problem]

The inventors of the present invention found that particles containing SLAN phosphors or nitride phosphors similar to its crystalline structure. Although the detailed mechanism is not yet clear, it is clear that by making the surface of the particles at least The composition of a fluorine-containing compound and setting the content of the fluorine element relative to the entire particle to a predetermined value or more can suppress the reduction of the fluorescence intensity in a water-exposed environment, that is, it can improve the moisture resistance.

According to the present invention, a surface-coated phosphor particle can be provided, comprising: phosphor-containing particles and a coating part covering the surface of the particle; the phosphor has the general formula M ¹ _a M ² _b M ³ _c Al ₃ N _4-d O _d represents the composition, but M ¹ is one or more elements selected from Sr, Mg, Ca and Ba, M ² is one or more elements selected from Li and Na, M ³ is one or more elements selected from Eu and Ce, the a, b, c, and d meet the following formulas: 0.850≦a≦1.150 0.850≦b≦1.150 0.001≦c≦0.015 0≦d≦0.40 0≦d/(a+d)<0.30 The coating constitutes at least a part of the outermost surface of the particle, and contains a fluorine-containing compound containing fluorine and aluminum. Relative to the entire surface-coated phosphor particle, fluorine The element content is 15% by mass or more and 30% by mass or less.

In addition, according to the present invention, a method for manufacturing the above-mentioned surface-coated phosphor particles can be provided, which includes the following steps: a mixing step, mixing the raw materials; a calcining step, calcining the mixture obtained from the mixing step; an acid treatment step, The calcined product obtained by the calcination step and the acid solution are mixed; and the fluorine treatment step is to mix the calcined product and the fluorine element-containing compound after the acid treatment step; in the mixing step, the molar ratio of the Al is set The input amount of the M ¹ at 3 o'clock is 1.10 or more and 1.20 or less in molar ratio.

In addition, according to the present invention, it is possible to provide a light-emitting device having the above-mentioned surface-coated phosphor particles and a light-emitting element. [Effects of Invention]

According to the present invention, it is possible to provide a technology for improving the moisture resistance of nitride phosphor particles.

Hereinafter, the embodiments of the present invention will be described in detail.

The surface-coated phosphor particles of the embodiment include: phosphor-containing particles, and a coating portion covering the surface of the particles. The following describes the details of surface-coated phosphor particles.

The phosphor composed of particles of this embodiment is represented by the general formula M ¹ _a M ² _b M ³ _c Al ₃ N _4-d O _d . a, b, c, 4-d, and d represent the molar ratio of each element.

In the above general formula, M ¹ is an element selected from one or more of Sr, Mg, Ca, and Ba. It is more desirable that M ¹ contains at least Sr. The lower limit of the molar ratio a of M ¹ is preferably 0.850 or more, more preferably 0.950 or more. On the other hand, ^{the upper limit of the molar ratio a of M 1} is preferably 1.150 or less, more preferably 1.100 or less, and even more preferably 1.050 or less. By making ^{the molar ratio a of M 1} fall within the above range, the stability of the crystal structure can be improved.

In the above general formula, M ² is one or more elements selected from Li and Na. It is more desirable that M ² contains at least Li. The lower limit of the molar ratio b of M ² is preferably 0.850 or more, more preferably 0.950 or more. On the other hand, ^{the upper limit of the molar ratio b of M 2} is preferably 1.150 or less, more preferably 1.100 or less, and even more preferably 1.050 or less. By making ^{the molar ratio a of M 2} fall within the above range, the stability of the crystal structure can be improved.

In the above general formula, M ³ is an activator added to the matrix crystal, that is, an element constituting the luminescence center ion of the phosphor, and is an element selected from one or more of Eu and Ce. M ³ can be selected according to the required emission wavelength, and ideally contains Eu at least. The lower limit of the molar ratio c of M ³ is preferably 0.001 or more, more preferably 0.005 or more. On the other hand, ^{the upper limit of the molar ratio c of M 3} is preferably 0.015 or less, more preferably 0.010 or less. By making ^{the lower limit of the molar ratio c of M 3} fall within the above range, sufficient luminous intensity can be obtained. In addition, by making ^{the upper limit of the molar ratio c of M 3} fall within the above range, it is possible to suppress concentration extinction and maintain the luminous intensity at a sufficient value.

In the above general formula, the lower limit of the molar ratio d of oxygen is preferably 0 or more, more preferably 0.05 or more. On the other hand, the upper limit of the molar ratio d of oxygen is preferably 0.40 or less, more preferably 0.35 or less. By making the molar ratio d of oxygen fall within the above range, the crystalline state of the phosphor can be stabilized and the luminous intensity can be maintained at a sufficient value. In addition, the content of oxygen in the phosphor is preferably less than 2% by mass, and more preferably less than 1.8% by mass. If the oxygen content is less than 2% by mass, the crystalline state of the phosphor can be stabilized and the luminous intensity can be maintained at a sufficient value.

The molar ratio of M ¹ and oxygen, that is, the lower limit of the value of d/(a+d) calculated from a and d is preferably 0 or more, more preferably 0.05 or more. On the other hand, the upper limit of the value of d/(a+d) is preferably less than 0.30, more preferably less than 0.25. By making d/(a+d) fall within the above range, the crystalline state of the phosphor can be stabilized and the luminous intensity can be maintained at a sufficient value.

The coating portion constitutes at least a part of the outermost surface of the phosphor-containing particles. The coating includes a fluorine-containing compound containing fluorine and aluminum. Among the fluorine-containing compounds, it is preferable that the fluorine element and the aluminum element be directly covalently bonded. More specifically, it is preferable that the fluorine-containing compound contains one or both of _{(NH 4} ) ₃ AlF ₆ or AlF ₃ . In addition, the fluorine-containing compound may be composed of a single compound containing a fluorine element and an aluminum element. By forming at least a part of the surface of the phosphor particles containing the above-mentioned covering part, the moisture resistance of the phosphor particles constituting the particles can be improved. In addition, from the viewpoint of further improving the moisture resistance of the phosphor, it is more desirable _{that the coating part contains AlF 3.}

The aspect of the coating part is not particularly limited, as long as the coating part covers at least a part of the surface of the particle, and it may also be the entire surface of the coating particle. As for the state of the coating, for example, a state in which a large number of particulate fluorine-containing compounds are dispersed on the surface of the phosphor-containing particles, and a state in which the fluorine-containing compound continuously covers the surface of the phosphor-containing particles kind.

In this embodiment, the content rate of the fluorine element with respect to the entire surface-coated phosphor particles is 15% by mass or more and 30% by mass or less. The moisture resistance can be improved by the content of the fluorine element relative to the entire surface-coated phosphor particles being 15% by mass or more. The content of the fluorine element relative to the entire surface-coated phosphor particles is 30% by mass or less, which improves the moisture resistance and maintains the luminous intensity at a sufficient value. The lower limit of the content of the fluorine element relative to the entire surface-coated phosphor particles is preferably 18% by mass or more, and more preferably 20% by mass or more. In addition, the upper limit of the content of the fluorine element relative to the entire surface-coated phosphor particles is preferably 27% by mass or less, and more preferably 25% by mass or less. By making the lower limit of the fluorine element content rate fall within the above range, the moisture resistance can be further improved. In addition, by making the upper limit of the content rate of the fluorine element fall within the above-mentioned range, the moisture resistance can be further improved and the emission intensity can be maintained at a sufficient value. In addition, the fluorine element is derived from the fluoride of the metal element used as the raw material described later, or is added in the fluorine treatment step described later, and does not constitute the crystal structure of the phosphor.

According to the surface-coated phosphor particles of this embodiment, it is possible to suppress the fluorescence intensity in a water-exposed environment, ideally it is possible to suppress the reduction of the fluorescence intensity in a high-humidity environment such as 90%RH or more, and it is more desirable to suppress the high temperature The reduction of fluorescence intensity in high humidity environment.

In the surface-coated phosphor particles of this embodiment, the diffuse reflectance with respect to light irradiation with a wavelength of 300 nm is preferably 56% or more, more preferably 58% or more, and still more preferably 60% or more. In addition, in the surface-coated phosphor particles, the diffuse reflectance of light irradiation with respect to the peak wavelength of the fluorescence spectrum is, for example, preferably 85% or more, and more preferably 86% or more. With such characteristics, the luminous efficiency can be further improved and the luminous intensity can be further improved.

As an example of the surface-coated phosphor particles of this embodiment, when excited by blue light with a wavelength of 455nm, the peak wavelength should fall within the range of 640nm or more and 670nm or less, and the half-value width should be 45nm or more and 60nm or less. With such characteristics, excellent color rendering and color reproducibility can be expected.

As an example of the surface-coated phosphor particles of this embodiment, when excited by blue light with a wavelength of 455nm, the color purity of the luminescent color should preferably be 0.680≦x<0.735 in the CIE-xy chromaticity diagram. With such characteristics, excellent color rendering and color reproducibility can be expected. If the x value is 0.680 or more, red light with better color purity can be expected. If the x value is 0.735 or more, it will exceed the maximum value in the CIE-xy chromaticity diagram. It is better to meet the above range.

In this embodiment, the type of acid and solvent in the acid treatment step, the acid concentration, the concentration of hydrofluoric acid, the time of hydrofluoric acid treatment in the hydrofluoric acid treatment step, and the heating performed after the hydrofluoric acid treatment The heating temperature and heating time in the step can be adjusted appropriately to form a fluorine-containing compound containing fluorine and aluminum on the surface of phosphor-containing particles, and the content of fluorine in the particles can be controlled to a predetermined value Within the range.

According to the above-mentioned surface-coated phosphor particles, the surface of the phosphor particles is coated by the coating part containing the fluorine-containing compound containing the fluorine element and the aluminum element, which can improve the moisture resistance of the nitride phosphor and can be used for a long time. Maintain luminous intensity.

(Method for manufacturing surface-coated phosphor particles) The surface-coated phosphor particles of this embodiment can be manufactured by the following steps: The mixing step in which the raw materials are mixed, the calcination step in which the mixture obtained in the mixing step is calcined, the acid treatment step in which the calcined product obtained in the calcining step and the acid solution are mixed, the calcined product that has undergone the acid treatment step, contains The fluorine treatment step in which compounds of fluorine elements are mixed. In addition to the above-mentioned steps, it is also possible to add a heating step of subjecting the resultant obtained in the fluorine treatment step to heat treatment.

(Mixing step) The mixing step is a step of mixing the raw materials weighed in such a way that the target surface-coated phosphor particles can be obtained to obtain a powdery raw material mixture. The method of mixing the raw materials is not particularly limited, and for example, a method of sufficiently mixing using a mixing device such as a mortar, a ball mill, a V-type mixer, and a planetary mill. In addition, for strontium nitride, lithium nitride, etc., which will react violently with moisture or oxygen in the air, it is more appropriate to use a glove box whose interior is replaced with an inert gas environment or use a mixing device.

In the mixing step, when the molar ratio of Al is set to 3, ^{the input amount of M 1} is preferably 1.10 or more in molar ratio. By setting ^{the input amount of M 1} to be 1.10 or more in terms of molar ratio, it is possible to suppress the ^{lack of M 1} in the phosphor due to volatilization ^{of M 1} in the calcination step, and M ¹ is not prone to defects, and the crystallinity of the crystal structure Can be maintained well. This result infers that a narrow-band fluorescence spectrum can be obtained and the luminous intensity can be improved. In addition, in the mixing step, when the molar ratio of Al is set to 3, ^{the input amount of M 1} should preferably be 1.20 or less in molar ratio. By making ^{the input amount of M 1} less than 1.20 in terms of molar ratio, ^{the increase of the out-of-phase containing M 1} can be suppressed, the out-of-phase in the acid treatment step can be easily removed, and the luminous intensity can be increased.

Each raw material used in the mixing step can be selected from one or more of the group consisting of the metal element of the metal element contained in the composition of the phosphor and the metal compound containing the metal element. Examples of metal compounds include nitrides, hydrides, fluorides, oxides, carbonates, and chlorides. Among them, considering that the luminous intensity of the phosphor can be improved, the nitride can be suitably used for the metal compound ^{containing M 1} and M ^2. Specifically, as for ^{the metal compound containing M 1} , for example, Sr ₃ N ₂ , SrN ₂ , SrN, etc. can be cited. As for ^{the metal compound containing M 2} , for example, Li ₃ N, LiN ₃ and the like can be cited. As for ^{the metal compound containing M 3} , for example, Eu ₂ O ₃ , EuN, EuF _{3 can} be mentioned. As for the metal compound containing Al, for example, AlN, AlH ₃ , AlF ₃ , LiAlH ₄ and the like can be cited. In addition, flux can also be added as necessary. As for the flux, for example, LiF, SrF ₂ , BaF ₂ , AlF ₃ and the like can be cited.

(Calcination step) The calcining step is to fill the mixture of the above-mentioned raw materials into the calcining vessel and calcinate. The aforementioned calcining vessel should preferably have a structure with improved airtightness, and the interior of the calcining vessel should be filled with non-oxidizing gases such as argon, helium, hydrogen, and nitrogen. The calcining container should preferably be made of materials that are stable under high-temperature ambient gas and are difficult to react with the mixture of raw materials and their reaction products. For example, it is preferable to use a container made of boron nitride, carbon, molybdenum or tantalum. Or a container made of high melting point metal such as tungsten is ideal.

[Calcination temperature] The lower limit of the calcination temperature in the calcination step is preferably 900°C or higher, more preferably 1000°C or higher, and more preferably 1100°C or higher. On the other hand, the upper limit of the calcination temperature is preferably 1500°C or less, more preferably 1400°C or less, and even more preferably 1300°C or less. By keeping the calcination temperature within the above range, unreacted raw materials after the completion of the calcination step can be reduced, and the decomposition of the main crystalline phase can be suppressed.

[Types of calcination ambient gas] Regarding the type of the calcining atmosphere in the calcining step, for example, a gas containing nitrogen as an element can be suitably used. Specifically, nitrogen and/or ammonia can be mentioned, and nitrogen is particularly preferable. In addition, in the same way, inert gases such as argon and helium can be suitably used. In addition, the calcining environment gas can be composed of one type of gas, or a mixed gas of many types of gas.

[Pressure of calcination ambient gas] The pressure of the calcination environment gas can be selected according to the calcination temperature, and is usually in the pressure state in the range of 0.1MPa･G or more and 10MPa･G or less. The higher the pressure of the calcination environment gas, the higher the decomposition temperature of the phosphor, but considering the industrial productivity, it is ideal to be 0.5MPa･G or more and 1MPa･G or less.

[Calcination time] The calcination time in the calcination step can be selected within a time range in which problems such as a large amount of unreacted substances, insufficient primary particle growth, or sintering between particles do not occur. In the method for producing surface-coated phosphor particles of the embodiment, the lower limit of the calcination time is preferably 0.5 hours or more, more preferably 1 hour or more, and more preferably 2 hours or more. In addition, the upper limit of the calcination time is preferably 48 hours or less, more preferably 36 hours or less, and more preferably 24 hours or less.

The state of the calcined product obtained by the calcination step may be in various states such as powdery or massive depending on the blending of the raw materials and the calcination conditions. In order to prepare for actual use as surface-coated phosphor particles, the obtained calcined product may be provided with a disintegration, pulverization step, and/or separation operation step to form a powder of a predetermined size. In addition, considering the average particle size of the surface-coated phosphor particles, considering the absorption efficiency of excitation light and sufficient luminous efficiency, when using the surface-coated phosphor particles for LEDs, it is preferable to set the surface-coated phosphor particles to The average particle size is adjusted to 5 μm or more and 30 μm or less. In addition, in order to prevent the mixing of impurities originating from the process in the above-mentioned disintegration and pulverization steps, the components of the machine contacting the calcined material should preferably be made of high toughness ceramics such as silicon nitride, alumina, and silicon aluminum oxynitride. ideal.

(Acid treatment step) The acidic solution used in the acid treatment step is preferably an aqueous solution. The contact with the acidic solution is generally, for example, the above-mentioned calcined product in an acidic aqueous solution containing at least one of nitric acid, hydrochloric acid, acetic acid, sulfuric acid, formic acid, and phosphoric acid. Disperse and stir for several minutes to several hours. Specifically, the above-mentioned calcined product is dispersed in a mixed solution of an organic solvent and an acidic solution, and after stirring for several minutes to several hours, it can be washed with an organic solvent. The acid treatment can dissolve and remove the impurity elements contained in the raw materials, the impurity elements originating from the calcination vessel, the heterogeneous phase generated in the calcination step, and the impurity elements mixed in the pulverization step. At the same time, the fine powder can be removed, so the scattering of light can be suppressed, and the light absorption rate of the phosphor can also be improved. In addition, as the organic solvent, alcohols such as methanol, ethanol, and 2-propanol, and ketones such as acetone can be used. The acidic solution is at least one of nitric acid, hydrochloric acid, acetic acid, sulfuric acid, formic acid, and phosphoric acid. Regarding the mixing ratio of these solutions, for example, it can be prepared so that the acidic solution has a concentration of 0.1% by volume or more and 3% by volume or less with respect to the organic solvent.

(Fluorine treatment step) In the fluorine treatment step, an aqueous hydrofluoric acid solution can be suitably used for the fluorine element-containing compound mixed into the calcined product subjected to the acid treatment step. The lower limit of the concentration of the hydrofluoric acid aqueous solution is preferably 25% or more, more preferably 27% or more, and more preferably 30% or more. On the other hand, the upper limit of the concentration of the hydrofluoric acid aqueous solution is preferably 38% or less, more preferably 36% or less, and more preferably 34% or less. By setting the concentration of the hydrofluoric acid aqueous solution to 25% or more, at least a part of the outermost surface of the phosphor-containing particles can be formed with a coating portion _{containing (NH 4} ) ₃ AlF _6. On the other hand, setting the concentration of the hydrofluoric acid aqueous solution to 38% or less can inhibit the reaction of particles and hydrofluoric acid from being too intense. The mixing of the calcined product after the acid treatment step and the hydrofluoric acid aqueous solution can be carried out by stirring means such as a stirrer. The lower limit of the mixing time of the above-mentioned calcined product and the aqueous hydrofluoric acid solution is preferably 5 minutes or more, more preferably 10 minutes or more, and more preferably 15 minutes or more. On the other hand, the upper limit of the mixing time of the above-mentioned calcined product and the hydrofluoric acid aqueous solution is preferably 30 minutes or less, more preferably 25 minutes or less, and even more preferably 20 minutes or less. By making the mixing time of the calcined product and the hydrofluoric acid aqueous solution fall within the above range, a coating _{containing (NH 4} ) ₃ AlF _{6 can be stably formed on at least a part of the outermost surface of the phosphor-containing particles.}

(Heating step) When the resultant obtained by the fluorine treatment contains (NH ₄ ) ₃ AlF ₆ as the coating portion, the heating step may be performed after the above step. The lower limit of the heating temperature in the heating step is preferably 220°C or higher, and more preferably 250°C or higher. On the other hand, the upper limit of the heating temperature is preferably 500°C or less, more preferably 450°C or less, and even more preferably 400°C or less. By setting the heating temperature to 220° C. or higher, (NH ₄ ) ₃ AlF _{6 can be} converted into AlF ₃ by the following reaction formula (1). (NH ₄ ) ₃ AlF ₆ →AlF ₃ +3NH ₃ +3HF･･･(1) On the other hand, by setting the heating temperature below 500°C, the crystalline structure of the phosphor can be maintained well and the luminous intensity can be improved. The lower limit of the heating time is preferably more than 1 hour, more preferably more than 1.5 hours, and more preferably more than 2 hours. On the other hand, the upper limit of the heating time is preferably 6 hours or less, more preferably 5.5 hours or less, and more preferably 5 hours or less. By keeping the heating time within the above range, (NH ₄ ) ₃ AlF _{6 can be more reliably converted into AlF 3} with higher moisture resistance. In addition, the heating step should preferably be carried out in the atmosphere or under a nitrogen atmosphere. Thereby, the substance itself that heats the ambient gas can produce the target substance without hindering the above-mentioned reaction formula (1).

According to the above-described method for producing surface-coated phosphor particles, it is possible to produce nitride phosphor particles that have improved moisture resistance and can maintain luminous intensity for a longer period of time.

(Light-emitting device) The light-emitting device of the embodiment has the surface-coated phosphor particles and the light-emitting element of the above-mentioned embodiment. As for the light-emitting element, ultraviolet LED, blue LED, fluorescent lamp can be used alone or in combination. It is desirable that the light-emitting element can emit light with a wavelength of 250 nm or more and 550 nm or less, and a blue LED light-emitting element of 420 nm or more and 500 nm or less is preferable.

Regarding the phosphor particles used in the light-emitting device, in addition to the surface-coated phosphor particles of the above-mentioned embodiment, phosphor particles having other luminous colors can also be used in combination. For phosphor particles of other luminescent colors, there are blue luminescent phosphor particles, green luminescent phosphor particles, yellow luminescent phosphor particles, orange luminescent phosphor particles, and red phosphor, for example : Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce, CaSc ₂ O ₄ : Ce, β-SiAlON: Eu, Y ₃ Al ₅ O ₁₂ : Ce, Tb ₃ Al ₅ O ₁₂ : Ce, (Sr, Ca, Ba) ₂ SiO ₄ : Eu, La ₃ Si ₆ N ₁₁ : Ce, α-SiAlON: Eu, Sr ₂ Si ₅ N ₈ : Eu, etc. The above-mentioned phosphor particles that can be used in combination with the surface-coated phosphor particles of the embodiment are not particularly limited, and can be appropriately selected in accordance with the brightness or color rendering required by the light-emitting device. By mixing the surface-coated phosphor particles of the above-mentioned embodiment with phosphor particles of other luminous colors, white of various color temperatures such as daylight white or bulb color can be realized. As far as light-emitting devices are concerned, there are lighting devices, backlight devices, image display devices, and signal devices.

In the light-emitting device of this embodiment, by using the phosphor particles coated on the surface of the above-mentioned embodiment, high light intensity can be achieved and reliability can be improved.

Above, the embodiments of the present invention have been described, but these are only examples of the present invention, and various configurations other than the above can be adopted. [Example]

Hereinafter, the present invention will be described with examples and comparative examples, but the present invention is not limited to these.

(Example 1) It is a ^{phosphor with a composition represented by M 1} _a M ² _b M ³ _c Al ₃ N _4-d O _d , in order to obtain one that conforms to M ¹ =Sr, M ² =Li, and M ³ =Eu , Sr ₃ N ₂ (manufactured by Taiheiyo Cement Corporation), Li ₃ N (manufactured by Materion Corporation), AlN (manufactured by Tokuyama Corporation), and Eu ₂ O ₃ (manufactured by Shin-Etsu Chemical Co., Ltd.) are used as raw materials as auxiliary materials. The flux is LiF (manufactured by Wako Pure Chemical Industries, Ltd.). When the molar ratio of Al is set to 3, the input amount of Sr is 1.15 of the molar ratio and the input amount of Eu is 0.0115 of the molar ratio. With respect to 100% by mass of the total amount of the aforementioned raw material mixture and flux, 5% by mass of LiF is added. In addition, Eu was injected in such a way that the injection amount when the molar ratio of Al was 3 as described above was 0.0115 of the molar ratio. Hereinafter, the manufacturing method of the surface-coated phosphor particles of Example 1 will be specifically described. AlN, Eu ₂ O ₃ and LiF are weighed and mixed in the air, and then the agglomerates are broken with a nylon sieve with a mesh of 150 μm to obtain a premix. Move the aforementioned premix to a glove box maintained at an inert atmosphere with moisture below 1 ppm and oxygen below 1 ppm. _{After that, after weighing the aforementioned Sr 3} N ₂ and Li ₃ N so that the value of a exceeds 15% and the value of b exceeds 20% in the stoichiometric ratio (a=1, b=1), they are additionally blended and mixed, Then, the agglomerated group is broken with a nylon sieve with a mesh of 150 μm to obtain a raw material mixture of the phosphor. Since Sr and Li are easily dispersed during calcination, they are blended in an amount larger than the theoretical value. Then, the aforementioned raw material mixture was filled into a cylindrical BN container with a lid (manufactured by Denka Co., Ltd.). Then, the container filled with the raw material mixture of the phosphor was taken out of the glove box, and placed in an electric furnace (manufactured by Fuji Denpa Co., Ltd.) with a carbon heater equipped with a graphite heat insulating material, and a calcination step was performed. At the beginning of the calcination step, the electric furnace is temporarily degassed to a vacuum state, and the calcination is started under a pressurized nitrogen atmosphere at room temperature to 0.8MPa･G. After the temperature in the electric furnace reaches 1100°C, maintain the temperature and continue calcination for 8 hours, and then cool to room temperature. After pulverizing the obtained calcined product with a mortar, it was sorted and recovered by a nylon sieve with a mesh of 75 μm. As an acid treatment step, MeOH (99%) (manufactured by Domestic Chemical Co., Ltd.) added HNO ₃ (60%) (manufactured by Wako Pure Chemical Industries, Ltd.) into a mixed solution with calcined powder and stirred for 3 hours After that, separation is performed to obtain phosphor powder. The obtained phosphor powder was added to a 30% hydrofluoric acid aqueous solution, and a fluorine treatment step was performed by stirring for 15 minutes. After the fluorine treatment step, decantation with MeOH was used to wash the solution until it became neutral, and after filtration for solid-liquid separation, the solid content was dried and all passed through a 45 μm sieve to untie the condensed clusters, thereby obtaining an example The surface of 1 is coated with phosphor particles.

(Example 2) After fluorine treatment, all the phosphor powders that pass through a 45μm mesh to dissolve the condensed phosphor powder are subjected to a heat treatment at 250°C for 4 hours in an atmospheric atmosphere, except that it is the same as in Example 1 The input amount and procedure of the raw materials to obtain the surface-coated phosphor particles of Example 2.

(Example 3) After fluorine treatment, all the phosphor powders that pass through a 45μm mesh to unwrap the condensed phosphor powder are subjected to a heat treatment at 300°C for 4 hours under atmospheric atmosphere, except that it is the same as in Example 1 The input amount and procedure of the raw materials to obtain the surface-coated phosphor particles of Example 3.

(Example 4) After fluorine treatment, all the phosphor powders that passed through a 45μm mesh to unwrap the condensed phosphor powder were subjected to a heating treatment at 350°C for 4 hours under atmospheric atmosphere, except that the same procedure as in Example 1 was carried out. The input amount and procedure of the raw materials to obtain the surface-coated phosphor particles of Example 4.

(Example 5) After fluorine treatment, all the phosphor powders that passed through a 45μm mesh to unwrap the condensed phosphor powder were subjected to a heat treatment at 400°C for 4 hours under atmospheric atmosphere, except that it was the same as in Example 1. The input amount and procedure of the raw materials to obtain the surface-coated phosphor particles of Example 5.

(Comparative example 1) Except that the fluorine treatment was not performed, the phosphor particles of Comparative Example 1 were obtained through the same raw material input amount and procedure as in Example 1.

(Comparative example 2) A 10% hydrofluoric acid aqueous solution was used for the fluorine treatment. The phosphor particles of Comparative Example 2 were obtained through the same raw material input amount and procedure as in Example 1 except that the 10% hydrofluoric acid aqueous solution was used.

(Comparative example 3) A 20% hydrofluoric acid aqueous solution was used for the fluorine treatment. The phosphor particles of Comparative Example 3 were obtained through the same raw material input amount and procedure as in Example 1 except that the 20% hydrofluoric acid aqueous solution was used.

For the surface-coated phosphor particles of each example and the phosphor particles of each comparative example, the chemical composition (that is, the general formula: M ¹ _a M ² _b M ³ _c Al ₃ N The subscripts a~d of each element of _4-d O _{d ).} The above subscripts a to d are obtained by analyzing the obtained phosphor particles by the following method. That is, an ICP emission spectrophotometer (manufactured by SPECTRO Co., Ltd., CIROS-120) is used for Sr, Li, Al, and Eu systems, and an oxygen and nitrogen analyzer (manufactured by Horiba Manufacturing Co., Ltd., EMGA- 920) based on the analysis results. The numerical values of a to d of the phosphors of the Examples and Comparative Examples are shown in Table 1.

(Analysis by X-ray diffraction method) For the surface-coated phosphor particles of each example and the phosphor particles of each comparative example, an X-ray diffraction device (UltimaIV manufactured by Rigaku Corporation) was used. The powder X-ray diffraction pattern confirmed its crystal structure. _{With respect to Example 1,} the peak portion _{corresponding to (NH 4} ) ₃ AlF 6 was confirmed in the range of 2θ above 16.5° and below 17.5°. _{For Examples 2 to 5,} the peaks corresponding to AlF 3 were confirmed in the range of 2θ above 14° and below 15°. On the other hand, in Comparative Examples 1 and 2, neither _{the peak corresponding to (NH 4} ) ₃ AlF ₆ nor the peak corresponding to AlF _{3 was} observed. In Comparative Example 3, no _{peak corresponding to AlF 3} was confirmed, but a small peak corresponding to (NH ₄ ) ₃ AlF _{6 was observed.}

(Surface analysis using XPS) For the surface-coated phosphor particles of each example and the phosphor particles of each comparative example, surface analysis using XPS was performed. For the surface-coated phosphor particles of each example, it was confirmed that Al and F existed and Al and F were covalently bonded on the outermost surface of the phosphor particles. On the other hand, in Comparative Examples 1 and 2, Al and F were not confirmed to be covalently bonded, and in Comparative Example 3, although it was weak, Al and F were confirmed to be covalently bonded. From the surface analysis results obtained by XPS and the analysis by X-ray diffraction method, it can be confirmed that the surface-coated phosphor particles of Example 1 are at least part of the outermost surface of the phosphor particles as (NH ₄ ) ₃ The surface-coated phosphor particles of Examples 2 to 5 are made of AlF ₆ and at least a part of the outermost surface of the phosphor particles is made of AlF ₃ . In addition, it can be considered that Comparative Examples 1 and 2 do not have (NH ₄ ) ₃ AlF ₆ and AlF _{3 on} the outermost surface of the phosphor particles, and Comparative Example 3 does not have AlF ₃ but slightly (NH ₄ ) ₃ AlF ₆ exists.

(Content rate of fluorine element) The content rate of the fluorine element relative to the entire surface-coated phosphor particles in each example and the content rate of the fluorine element relative to the entire phosphor particle in each comparative example are based on the use of a sample combustion device (Mitsubishi Chemical Analysis Technology Co., Ltd. product, AQF-2100H) and ion chromatography (Nippon Dionex KK Co., Ltd. product, ICS1500) were calculated based on the analysis results.

(Diffuse reflectance) The diffuse reflectance was measured by attaching an integrating sphere device (ISV-469) to an ultraviolet-visible spectrophotometer (V-550) manufactured by JASCO Corporation. Use a standard reflector (spectralon) for baseline calibration, and install a solid sample holder filled with surface-coated phosphor particles of each embodiment or phosphor particles of each comparative example, and implement diffuse reflection of light with a wavelength of 300nm Measurement of the diffuse reflectance of light at the peak wavelength.

(Luminous characteristics) The chromaticity x is measured by a spectrophotometer (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.), and calculated by the following program. The surface-coated phosphor particles of each example or the phosphor particles of each comparative example were filled in such a way that the surface of the concave light analysis tube was smooth, and an integrating sphere was installed. Use optical fiber to split blue monochromatic light with a wavelength of 455nm from the light source (Xe lamp) into this integrating sphere. Use this monochromatic light as the excitation light source to irradiate the sample of the phosphor to perform the fluorescence spectrum measurement of the sample. Calculate the peak wavelength and the half-value width of the peak from the obtained spectral data. In addition, the chromaticity x is based on the wavelength domain information in the range of 465nm to 780nm of the fluorescence spectrum information according to JIS Z 8724:2015, and the CIE chromaticity coordinate x value (color) in the XYZ color system specified in JIS Z 8781-3:2016 is calculated. Degree x).

(Luminous intensity ratio before and after the high-temperature and high-humidity test) For the surface-coated phosphor particles of each example and the phosphor particles of each comparative example, the luminous intensity I ₀ before the start of the high-temperature and high-humidity test was measured. _{Then, using a thermohygrostat (manufactured by Daiwa Scientific Co., Ltd., IW-222), the luminous intensity I 1} after 50 hours of high temperature and high humidity test placed in an environment of 60° C. and 90% RH was measured. _{The emission intensity ratio I 1} /I ₀ (%) was calculated from the obtained measurement value. _{In addition, the luminous intensity I 2} after 100 hours of high temperature and high humidity test placed in an environment of 60°C and 90% RH was measured. _{The emission intensity ratio I 2} /I ₀ (%) was calculated from the obtained measurement value. Table 1 shows the results obtained regarding the luminous intensity ratios I ₁ /I ₀ and I ₂ /I _0. In addition, the measurement of the luminous intensity was performed using a spectrofluorometer (manufactured by Hitachi Advanced Technology Co., Ltd., F-7000) calibrated with Rose Bengal B and a substandard light source. That is, a solid sample holder attached to the photometer was used to measure the fluorescence spectrum with an excitation wavelength of 455 nm. The peak wavelength of the fluorescence spectrum of the surface-coated phosphor particles of each example and the phosphor particles of Comparative Example 3 is 656 nm. In addition, the peak wavelength of the fluorescence spectrum of the phosphor particles of Comparative Examples 1 and 2 was 657 nm. The intensity value of the peak wavelength of the fluorescence spectrum is used as the luminous intensity of the surface-coated phosphor particles or phosphor particles.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative example 1 Comparative example 2 Comparative example 3 Sr ratio invested (※1) 1.15 1.15 1.15 1.15 1.15 1.15 1.15 1.15 Phosphor particle composition (subscript of general formula) and value of d/(a+d) a 1.02 1.02 1.00 1.01 1.01 0.96 0.94 0.95 b 0.99 0.98 0.97 0.96 0.97 0.95 0.97 0.97 c 0.009 0.008 0.008 0.008 0.008 0.008 0.008 0.008 d 0.34 0.08 0.07 0.11 0.15 0.36 0.14 0.21 d/(a+d) 0.25 0.07 0.07 0.10 0.13 0.27 0.13 0.18 Hydrofluoric acid treatment 30% hydrofluoric acid aqueous solution 30% hydrofluoric acid aqueous solution 30% hydrofluoric acid aqueous solution 30% hydrofluoric acid aqueous solution 30% hydrofluoric acid aqueous solution no 10% hydrofluoric acid aqueous solution 20% hydrofluoric acid aqueous solution Heating temperature (℃) No heat treatment 250 300 350 400 No heat treatment No heat treatment No heat treatment Analysis using X-ray diffraction (NH ₄ ) ₃ AlF ₆ AlF ₃ AlF ₃ AlF ₃ AlF ₃ no no (NH ₄ ) ₃ AlF ₆ Fluorine element content rate (mass%) 23.1 21.3 22.6 22.2 20.8 0.14 8.7 13.6 Diffuse reflectance (%) 300nm 76 75 73 68 69 75 73 74 Peak wavelength 93 93 89 88 86 92 93 93 Peak wavelength (nm) 656 656 656 656 656 657 657 656 Half width (nm) 56 56 55 55 54 57 56 56 CIE x value 0.711 0.711 0.709 0.711 0.709 0.710 0.711 0.710 Luminous intensity ratio after 50 hours of high temperature and high humidity test I ₁ /I ₀ (%) 91 98 100 94 89 25 26 19 Luminous intensity ratio after 100 hours of high temperature and high humidity test I ₂ /I ₀ (%) 46 97 99 94 85 twenty three twenty three 13 ※1 Let the molar ratio of Al be the molar ratio of Sr at 3

As shown in Table 1, at least a part of the outermost surface of the phosphor particles is composed of a coating part of a fluorine-containing compound containing fluorine and aluminum. The results are obtained after 50 hours of high temperature and high humidity test The decrease in luminous intensity was significantly suppressed, and compared with Comparative Examples 1 to 3, it was confirmed that the luminous intensity ratio I ₁ /I _{0 was} greatly improved, and it was confirmed that the moisture resistance was excellent. In addition, in Examples 2 to 4, it can be confirmed that the luminous intensity ratio I ₂ /I _{0 after the 100-hour high-temperature and high-humidity test is compared to the luminous intensity ratio I 1} /I after the 50-hour high-temperature and high-humidity test. _{There is almost no decrease after 0} , and the moisture resistance is especially excellent. In addition, in Comparative Example 3, because _{the yield of (NH 4} ) ₃ AlF ₆ was insufficient, it was considered that sufficient moisture resistance could not be obtained.

This application claims priority based on Japanese application Japanese Patent Application No. 2019-074459 filed on April 9, 2019, and its entire content is incorporated into the present invention in its entirety.

no

Claims (11)

A surface-coated phosphor particle, comprising: a particle containing a phosphor and a coating part covering the surface of the particle; the phosphor has the general formula M ¹ _a M ² _b M ³ _c Al ₃ N _4-d O _d Represents the composition, but M ¹ is selected from more than one element of Sr, Mg, Ca and Ba, M ² is selected from more than one element of Li and Na, and M ³ is selected from One or more elements of Eu and Ce, the a, b, c, and d meet the following formulas: 0.850≦a≦1.150 0.850≦b≦1.150 0.001≦c≦0.015 0≦d≦0.40 0≦d/( a+d)<0.30 The coating constitutes at least a part of the outermost surface of the particle, and contains a fluorine-containing compound containing fluorine and aluminum. The content of fluorine is relative to the entire surface-coated phosphor particle 15% by mass or more and 30% by mass or less. The surface-coated phosphor particles of claim 1, wherein in the fluorine-containing compound, the fluorine element and the aluminum element are directly covalently bonded. The surface-coated phosphor particles of claim 1 or 2, wherein the fluorine-containing compound contains either or both of _{(NH 4} ) ₃ AlF ₆ or AlF _3. The surface-coated phosphor particle of claim 1 or 2, wherein the M ¹ contains at least Sr, the M ² contains at least Li, and the M ³ contains at least Eu. The surface-coated phosphor particles of claim 1 or 2, wherein the diffuse reflectance relative to light irradiation with a wavelength of 300 nm is 56% or more, and the diffuse reflectance relative to light irradiation with the peak wavelength of the fluorescence spectrum is 85 %the above. For example, the surface-coated phosphor particles of claim 1 or 2, wherein when excited by blue light with a wavelength of 455 nm, the peak wavelength falls within the range of 640 nm or more and 670 nm or less, and the half-value width is 45 nm or more and 60 nm or less. For example, the surface-coated phosphor particles of claim 1 or 2, wherein when excited by blue light with a wavelength of 455nm, the color purity of the luminescent color is in the CIE-xy chromaticity diagram, and the value of x meets 0.680≦x<0.735. A method for producing surface-coated phosphor particles is the method for producing surface-coated phosphor particles according to any one of claims 1 to 7, comprising the following steps: a mixing step, mixing raw materials; a calcination step, The mixture obtained in the mixing step is calcined; the acid treatment step is to mix the calcined product obtained from the calcining step and the acid solution; and the fluorine treatment step is to mix the calcined product and the fluorine element-containing compound after the acid treatment step ^{In the mixing step, the input amount of M 1} when the molar ratio of Al is set to 3 is 1.10 or more and 1.20 or less in terms of molar ratio. The method for producing surface-coated phosphor particles according to claim 8, wherein, in the acid treatment step, the acidic solution uses a hydrofluoric acid aqueous solution with a fluorine concentration of 25% or more. The method for producing surface-coated phosphor particles according to claim 8, which further includes a heating step, and heat treatment is applied to the result obtained by the fluorine treatment step. A light-emitting device having: the surface-coated phosphor particles according to any one of claims 1 to 7, and a light-emitting element.