TW202106858A - Surface-coated phosphor particle and light emitting device - Google Patents

Abstract

A surface-coated phosphor particle of the invention comprises a particle containing a phosphor and a coating section that coats the surface of the particle, wherein the phosphor has a predetermined composition, the coating section forms at least a portion of the outermost surface of the particle and contains AlF₃ , and in an X-ray diffraction pattern of the surface-coated phosphor particle measured using a Cu-Kα beam, if the light emission intensity of a maximum peak A for which 2θ is within a range from 23° to 26° is deemed I_A , and the light emission intensity of a maximum peak B for which 2θ is within a range from 36° to 39° is deemed I_B , then I_A and I_B satisfy I_A /I_B ≤ 0.10.

Description

Surface coated phosphor particles and light emitting device

The present invention relates to surface-coated phosphor particles and light-emitting devices.

So far, a variety of phosphors have been developed. With respect to such a technique, for example, a technique described in Patent Document 1 is known. Patent Document 1 has a description of SrLiAl ₃ N ₄ : Eu, which is a SLAN phosphor (claim 1, paragraph 0113, etc. of Patent Document 1). [Prior Technical Document] [Patent Document]

[Patent Document 1] International Publication No. 2013/175336

[The problem to be solved by the invention]

However, the inventors of the present case conducted research and found that the phosphor particles described in Patent Document 1 above still have room for improvement in terms of their luminous intensity characteristics in a high-temperature and high-humidity environment. [Means to solve the problem]

It is known that the luminescence intensity of phosphor particles obtained by calcination is greatly reduced when used in a high-temperature and high-humidity environment.

The inventor of the present case has further explored and found that by applying appropriate heat treatment to the surface-coated phosphor particles, the luminous intensity characteristics in a high temperature and high humidity environment can be improved. Although the detailed mechanism is not yet known, it is presumed that the surface layer of the phosphor particles is stabilized, and the deterioration of the luminescence characteristics can be suppressed even under high temperature and high humidity conditions.

Based on such knowledge and insights, it was found that the X-ray diffraction pattern of the surface-coated phosphor particles obtained by measuring with Cu-Kα rays will have 2θ in the range of 23° or more and 26° or less. the maximum emission intensity of the peaks a to I _a, 2 [Theta] at 36 ° above the light emission intensity of the maximum peak portion B is in the range of 39 ° or less and the time for the I _a I _B / I _B as an index, whereby stable Evaluate the degree of stabilization of the surface layer of the surface-coated phosphor particles. Furthermore, by setting I _A /I _B within an appropriate value range, a surface coating with excellent luminous intensity characteristics under high-temperature and high-humidity environments can be achieved. Phosphor particles, thus completing the present invention.

According to the present invention, a surface-coated phosphor particle can be provided, 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 The composition represented by N _4-d O _d ^{, but M 1} is selected from more than one element of Sr, Mg, Ca and Ba, and M ² is selected from more than one element of Li, Na and K The element of M ³ is selected from more than one element of Eu, Ce and Mn, and 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 AlF ₃ ; the surface-coated fluorescent obtained by measuring with Cu-Kα rays In the X-ray diffraction pattern of the photobody particle, the luminous intensity of the largest peak A in the range of 2θ between 23° and 26° is I _A , and the maximum peak in the range of 2θ between 36° and 39°. When the luminous intensity of part B is I _B , I _A and I _B meet I _A /I _B ≦0.10.

Furthermore, 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 surface-coated phosphor particles with excellent luminous intensity characteristics in a high-temperature and high-humidity environment, and a light-emitting device using the same.

The surface-coated phosphor particles of this embodiment will be described.

The surface-coated phosphor particles of this embodiment include phosphor-containing particles and phosphor particles that coat the surface of the particles.

The phosphor contained in the surface-coated phosphor particles has _a composition represented by the ^{general formula M 1} a M ² _b M ³ _c Al ₃ N _4-d O _d. In the general formula, 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, Na and K, and M ³ is selected It is composed of more than one element of Eu, Ce and Mn. In the general formula, a, b, c, 4-d, and d represent the molar ratio of each element.

The a, b, c, and d in the general formula conform to 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

M ¹ is an element selected from one or more of Sr, Mg, Ca, and Ba, and preferably contains at least Sr. The lower limit of the molar ratio a of M ¹ is preferably 0.850 or more, and 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 setting ^{the molar ratio a of M 1 to} fall within the above range, the stability of the crystal structure can be improved.

M ² is one or more elements selected from Li, Na and K, and preferably contains at least Li. The lower limit of the molar ratio b of M ² is preferably 0.850 or more, and 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 setting ^{the molar ratio a of M 2 to} fall within the above range, the stability of the crystal structure can be improved.

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, Ce, and Mn. M ³ can be selected according to the required emission wavelength, and should preferably contain at least Eu. The lower limit of the molar ratio c of M ³ is preferably 0.001 or more, and 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, and more preferably 0.010 or less. By setting ^{the lower limit of the molar ratio c of M 3 to} fall within the above range, sufficient luminous intensity can be obtained. In addition, by setting ^{the upper limit of the molar ratio c of M 3 to} fall within the above range, concentration quenching can be suppressed and the luminous intensity can be maintained at a sufficient value.

The lower limit of the molar ratio d of oxygen (O) is preferably 0 or more, and 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, and more preferably 0.35 or less. By setting the molar ratio d of oxygen to 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, and 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, and more preferably less than 0.25. By setting d/(a+d) to 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.

In the fluorine-containing compound, it is desirable that the fluorine element and the aluminum element be directly covalently bonded. More specifically, it is desirable that the fluorine-containing compound contains 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 outermost surface of the phosphor-containing particle by the coating containing the fluorine-containing compound, the moisture resistance of the phosphor constituting the particle can be improved. In addition, from the viewpoint of further improving the moisture resistance of the phosphor, it is preferable _{that the coating portion contains AlF 3.}

The state of the covering part is not particularly limited. Regarding the state of the coating, for example, a state in which many particulate fluorine-containing compounds are distributed on the surface of the phosphor-containing particles, or a state in which the fluorine-containing compound is continuously coated on the phosphor-containing particles The appearance of the surface. The coating portion may be configured to cover a part of the particle surface or the entire particle surface.

For the surface-coated phosphor particles, an X-ray diffraction pattern is obtained by X-ray diffraction using Cu-Kα rays. In the obtained X-ray diffraction pattern, the emission intensity of the largest peak A in the range of 2θ between 23° and 26° is I _A , and the maximum peak in the range of 2θ between 36° and 39°. The luminous intensity of _{B is I B.} At this time, in the surface-coated phosphor particles of this embodiment, I _A and I _B satisfy I _A /I _B ≦0.10. (Measurement method of X-ray diffraction pattern) For the surface-coated phosphor particles, the diffraction pattern was measured using an X-ray diffraction device under the following measurement conditions. (Measurement conditions) X-ray light source: Cu-Kα rays (λ=1.54184Å), output setting: 40kV･40mA Optical system: Concentration method Detector: Semiconductor detector Optical conditions for measurement: Divergent grating = 2/3° Scattering grating =8mm Light receiving grating = position of open diffraction peak = 2θ (angle of diffraction) Measuring range: 2θ=20°~70° Scanning speed: 2 degrees (2θ)/sec, continuous scanning scanning axis: 2θ/θ sample Preparation: Load the powdered surface-coated phosphor particles on the sample holder. The peak intensity is a value obtained by performing background correction.

Based on the knowledge and insights of the inventors of the present case, it is found that by applying appropriate heat treatment to the surface-coated phosphor particles, the luminous intensity characteristics in a high temperature and high humidity environment can be improved. Although the detailed mechanism has not yet been determined, it is presumed that the surface layer of the phosphor particles is stabilized to suppress the degradation of the luminescence characteristics even under high temperature and high humidity conditions.

Based on such knowledge and insights, it was found that the luminous intensity of the largest peak A in the X-ray diffraction pattern obtained by the X-ray diffraction method in the range of 23° or more and 26° or less is set to I _A , 2θ in the range of 36° or more and 39° or less. The luminous intensity of the largest peak B in the range of 36° or more and 39° or less is I _A /I _{B when the luminous intensity of I B} is used as an index, so that the surface of the surface-coated phosphor particles can be evaluated stably The degree of layer stabilization, and further, by setting I _A /I _B within an appropriate value range, a surface-coated phosphor particle with excellent luminous intensity characteristics in a high temperature and high humidity environment can be achieved.

The upper limit of I _A /I _B is 0.10 or less, preferably 0.09 or less, more preferably 0.08 or less, and even more preferably 0.07 or less. Thereby, the luminous intensity characteristics under high temperature and high humidity environment can be improved. On the other hand, _{the lower limit of I A} /I _B is not particularly limited.

Here, the maximum peak portion A of the luminous intensity I _A includes the peak portion _{derived from SrAlF 5. The maximum peak B} of the luminous intensity I B includes the peak from SLAN.

In this embodiment, for example, by appropriately selecting the type and blending amount of the raw material components used for the surface-coated phosphor particles, the production method of the surface-coated phosphor particles, etc., the above-mentioned I _A and I _A /I can be controlled. _B. Among them, the requirements for making the above I _A and I _A /I _B fall within the expected numerical range include, for example, after the calcination treatment, acid treatment and hydrofluoric acid treatment, and heating treatment temperature Fall within the appropriate range and so on.

Hereinafter, the characteristics of the surface-coated phosphor particles will be described.

In the surface-coated phosphor particles, the diffuse reflectance for light irradiation with a wavelength of 300 nm is, for example, 56% or more, more preferably 65% or more, and more preferably 70% or more. In addition, in the surface-coated phosphor particles, the diffuse reflectance for light irradiation at the peak wavelength of the fluorescence spectrum is, for example, 80% or more, 83% or more is more preferable, and 85% or more is more preferable. By having such a diffuse reflectance, the luminous efficiency can be further improved and the luminous intensity can be further improved.

When excited by blue light with a wavelength of 455nm, the surface-coated phosphor particles can also have the following composition: the peak wavelength, for example, falls within the range of 640nm or more and 670nm or less, and the half-height width falls within the range of 45nm or more and 60nm or less, for example . With such characteristics, excellent color rendering and color reproducibility can be expected.

When excited by blue light with a wavelength of 455 nm, the surface-coated phosphor particles may also have the following composition: the value of x in the CIE-xy chromaticity diagram meets, for example, 0.680≦x<0.735. With such characteristics, excellent color reproducibility can be expected. If the x value is 0.680 or more, red light with good 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, so it is ideal to meet the above range.

Hereinafter, the manufacturing method of the surface-coated phosphor particles of this embodiment will be described.

The method for producing surface-coated phosphor particles is to produce a phosphor particle (surface-coated phosphor particle), which has the following composition: including at least one selected from the group consisting of Sr, Mg, Ca, and Ba One element M ^{1 ; at least one element M 2} selected from the group consisting of Li, Na and K; at least one element selected from the group consisting of Eu, Ce and Mn Element M ³ ; and the group consisting of Al and N.

The method for producing surface-coated phosphor particles may include a mixing step, a calcination step, a pulverization step, an acid treatment step, a hydrofluoric acid treatment step, and a heat treatment step. Detailed description of each step.

(Mixing step) In the mixing step, the raw materials weighed in order to obtain the intended surface-coated phosphor particles are mixed to obtain a powdery raw material mixture.

The method of mixing the raw materials is not particularly limited. 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 roll 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 or a mixing device that replaces the inside with a passive gas environment.

^{In the mixing step, the input amount of M 1} when the molar ratio of Al is set to 3 is preferably 1.10 or more in terms of molar ratio. By setting ^{the input amount of M 1} to 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 can be maintained good. It is speculated that as a result, a narrow-band fluorescence spectrum can be obtained and the luminous intensity can be improved. ^{In addition, in the mixing step, the input amount of M 1} when the molar ratio of Al is set to 3 is preferably 1.20 or less in molar ratio. By setting ^{the input amount of M 1 to} less than 1.20 in terms of molar ratio, ^{the increase of the out-of-phase containing M 1} can be suppressed, and the acid treatment step can be used to easily remove the out-of-phase and increase the luminous intensity.

Each raw material used in the mixing step may include one or more selected from the group consisting of a single metal element of a metal element contained in the composition of the phosphor and a 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, for ^{the metal compound containing M 1} , for example, Sr ₃ N ₂ , Sr ₂ N, 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.

If necessary, flux can also be added. As for the flux, for example, LiF, SrF ₂ , BaF ₂ , AlF ₃ and the like can be cited. These can be used individually or in combination of 2 or more types.

(Calcination step) The calcining step is, for example, filling the mixture of the above-mentioned raw materials into the interior of the calcining vessel and calcining.

It is ideal for the calcining vessel to have a structure that can improve air tightness. The calcining container is ideally composed of materials that are stable under high-temperature ambient gas and are not easy to react with the mixture of raw materials and their reaction products. For example, use containers made of boron nitride, carbon, molybdenum or tantalum or tungsten, etc. Containers made of high melting point metals are ideal.

The inside of the calcining vessel is filled with non-oxidizing gases such as argon, helium, hydrogen, nitrogen, etc., which 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 even 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 setting 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 crystal phase can be suppressed.

[Types of calcination ambient gas] Regarding the type of the calcining atmosphere gas in the calcining step, for example, a gas containing nitrogen element can be suitably used. Specifically, for example, nitrogen gas and/or ammonia gas can be cited, and nitrogen gas is particularly preferable. In addition, in the same way, inactive gases such as argon and helium can also be suitably used. In addition, the calcination environment gas can be composed of one type of gas, or a mixed gas of multiple 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 calcining 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 is selected to be within a time range that does not cause problems such as the presence of a large amount of unreacted substances, insufficient growth of phosphor particles, or reduction in productivity. 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 even more preferably 24 hours or less.

(Crushing step) The pulverization step is to pulverize the raw material mixture (calcined product) after the calcination step to obtain a pulverized product.

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. Through the decomposition-pulverization step and/or the classification operation step, the calcined product can be made into a powder with a predetermined size.

In order to prevent the mixing of impurities from the process in the above-mentioned decomposition and pulverization step, the components of the machine in contact with the calcined product are preferably composed of silicon nitride, aluminum oxide, silicon aluminum oxynitride (SiAlON), and the like.

In addition, the average particle size of the pulverized product can also be adjusted so that the average particle size of the surface-coated phosphor particles becomes 5 μm or more and 30 μm or less. As a result, the surface-coated phosphor particles will have excellent excitation light absorption efficiency and luminous efficiency, and can be applied to LED applications.

(Acid treatment step) In the acid treatment step, the pulverized product is subjected to acid treatment using an acid-containing solution.

For the acid-containing solution, a mixed liquid containing acid and solvent can be used. A mixed liquid of acid and organic solvent is ideal, and a mixed aqueous solution of acid and organic solvent is more ideal.

As the acid, for example, an inorganic acid may also be used. Specifically, nitric acid, hydrochloric acid, acetic acid, sulfuric acid, formic acid, phosphoric acid, etc. may be mentioned. These can be used individually or in combination of 2 or more types.

As the solvent, water solvents and organic solvents can be used.

Examples of organic solvents include alcohol and acetone. Among them, alcohol is preferable. As for the alcohol, for example, methanol, ethanol, 2-propanol, etc. can be used.

The mixing ratio of the organic solvent in the mixed liquid can also be prepared, for example, in such a way that the acid is 0.1% by volume or more and 3% by volume relative to 100% by volume of the mixed liquid containing the acid and the solvent.

The acid treatment can dissolve and remove the impurity elements contained in the raw materials, the impurity elements from the calcination vessel, the heterogeneous phase generated in the calcination step, and the impurity elements mixed in the pulverization step. Since the fine powder can also be removed at the same time, the scattering of light can be suppressed, and the light absorption rate of the phosphor can also be improved. That is, the acid treatment can wash away foreign matter and the like.

As an example of the acid treatment, after washing with an acid, washing with an organic solvent may be used, or a mixed solution containing an acid and an organic solvent may be used for washing. In addition, the ground product may be dispersed and immersed in an acid-containing solution, for example, for about 0.5 hours to 5 hours.

(Hydrofluoric acid treatment step) Hydrofluoric acid treatment is to apply hydrofluoric acid treatment to the crushed material after the acid treatment step.

For the hydrofluoric acid treatment, an aqueous solution of hydrofluoric acid can be suitably used for compounds containing fluorine elements. The lower limit of the concentration of the hydrofluoric acid aqueous solution is preferably 20% by mass or more, more preferably 25% by mass or more, and more preferably 30% by mass or more. On the other hand, the upper limit of the concentration of the hydrofluoric acid aqueous solution is preferably 40% by mass or less, more preferably 38% by mass or less, and more preferably 35% by mass or less. By setting the concentration of the hydrofluoric acid aqueous solution to be equal to or higher than the above-mentioned lower limit, 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 below the above upper limit can suppress the reaction of particles and hydrofluoric acid from being too intense.

The mixing of the pulverized product and the hydrofluoric acid aqueous solution can be performed by a stirring means such as a stirrer. The lower limit of the mixing time between the pulverized product and the hydrofluoric acid aqueous 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 setting the mixing time of the pulverized product and the hydrofluoric acid aqueous solution within the above range, a coating _{containing (NH 4} ) ₃ AlF _{6 can be stably formed on at least part of the outermost surface of the phosphor-containing particle} .

In this embodiment, by appropriately adjusting the type of acid and solvent in the acid treatment step, the concentration of the acid, the concentration of hydrofluoric acid in the hydrofluoric acid treatment step, the time of the hydrofluoric acid treatment, and after the hydrofluoric acid treatment The heating temperature and heating time in the heating treatment step can form a coating part covering the surface of the phosphor-containing particles.

(Heat treatment step) The heat treatment is to heat the ground material after hydrofluoric acid treatment in the atmosphere.

When the product obtained by the hydrofluoric acid treatment contains (NH ₄ ) ₃ AlF ₆ as a coating portion, a part or all of _{(NH 4} ) ₃ AlF _{6 can be changed to AlF 3} by performing a heat treatment step.

The lower limit of the heating temperature in the heat treatment step is preferably 220°C or higher, and more preferably 250°C or higher. On the other hand, the upper limit of the above heating temperature is preferably 380°C or less, more preferably 350°C or less, and even more preferably 330°C or less.

By setting the heating temperature to be equal to or higher than the above lower limit, (NH ₄ ) ₃ AlF _{6 can be} converted into AlF ₃ by performing the following reaction formula (1). (NH ₄ ) ₃ AlF ₆ →AlF ₃ +3NH ₃ +3HF･･･(1)

On the other hand, by making the heating temperature below the above upper limit, 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 1 hour or more, more preferably 1.5 hours or more, and more preferably 2 hours or more. 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 even more preferably 5 hours or less. By setting the heating time within the above range, (NH ₄ ) ₃ AlF ₆ can be reliably converted into AlF _{3 having} higher moisture resistance.

In addition, the heat treatment step is preferably carried out in the air or in a nitrogen atmosphere. Thereby, the substance in the heating environment can produce the target substance without hindering the above-mentioned reaction formula (1).

Hereinafter, the light-emitting device of this embodiment will be described. The light-emitting device of this embodiment has phosphor particles coated on the surface and a light-emitting element.

As for the light-emitting element, a single unit of ultraviolet LED, blue LED, fluorescent lamp or a combination of them can be used. The light-emitting element is desirably capable of emitting light with a wavelength of 250 nm or more and 550 nm or less. Among them, a blue LED light-emitting element having a wavelength of 420 nm or more and 500 nm or less is preferable.

As far as phosphor particles are concerned, in addition to surface-coated phosphor particles, phosphor particles with 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 phosphors, 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, and the like.

Other phosphor particles are not particularly limited, and can be appropriately selected according to the brightness or color rendering properties required by the light-emitting device. By mixing the surface-coated phosphor particles with phosphor particles of other luminous colors, white with various color temperatures such as daylight white or bulb color can be achieved.

Specific examples of the light-emitting device include, for example, an illumination device, a backlight device, an image display device, and a signal device.

The light-emitting device, by having phosphor particles coated on the surface, can achieve high luminous intensity and at the same time improve reliability.

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. In addition, the present invention is not limited to the above-mentioned embodiments, and changes, improvements, etc. within the scope of achieving the purpose of the present invention are also included in the present invention. [Example]

In the following, the present invention will be described in detail with reference to the embodiments, but the present invention is not limited to the description of these embodiments.

<Production of phosphor particles> (Comparative Example 1) [Mixing Step] In the atmosphere, AlN (manufactured by Tokuyama Co., Ltd.), Eu ₂ O ₃ (manufactured by Shin-Etsu Chemical Co., Ltd.) and LiF (Fuji Film Wako Pure Chemical Industries, Ltd.) After weighing and mixing, the agglutination is decomposed and broken by a nylon sieve with a mesh of 150 μm to obtain a premix. Move the premix to a glove box that is maintained at a passive atmosphere with moisture below 1 ppm and oxygen below 1 ppm. _{After that, Sr 3} N2 (manufactured by Taiheiyo Cement Corporation) and Li ₃ N (manufactured by Materion Co., Ltd.) were used in a stoichiometric ratio (a=1, b=1) with a value exceeding 15% and b value exceeding 20%. After weighing, the mixture is further blended and mixed, and then the agglomeration is decomposed and broken by 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. Here, when the molar ratio of Al is set to 3, the input amount of Sr is 1.15 in molar ratio, and the input amount of Eu is 0.01 in 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 was added. In addition, Eu is the same as described above, and the input amount when the molar ratio of Al is set to 3 is 0.01 in terms of molar ratio.

[Calcination step] Then, the 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.) equipped with a carbon heater equipped with a graphite heat insulating material, and the firing step was performed. At the beginning of the calcination step, the electric furnace is temporarily degassed to a vacuum state, and then the calcination is started from room temperature in a pressurized nitrogen atmosphere of 0.8MPa･G. After the temperature in the electric furnace reaches 1100°C, maintain the temperature for 8 hours and continue calcination, and then cool to room temperature.

[Crushing step] After pulverizing the obtained calcined product with a mortar, it was classified with a nylon sieve with a mesh of 75 μm and recovered.

[Acid treatment step] To MeOH (99%) (manufactured by Domestic Chemical Co., Ltd.) added HNO ₃ (60%) (manufactured by Wako Pure Chemical Industries Co., Ltd.), add the powder of the calcined product obtained and stir. After 3 hours, classification was performed to obtain phosphor powder.

[Hydrofluoric acid treatment steps] The hydrofluoric acid treatment step was implemented by adding the obtained phosphor powder to a 30% hydrofluoric acid aqueous solution and stirring for 15 minutes. After the hydrofluoric acid treatment step, the whole was passed through a 45 μm mesh to decompose the agglomerates, and the phosphor particles of Comparative Example 1 were obtained.

(Comparative example 2) The phosphor powder obtained by decomposing agglomerates by applying hydrofluoric acid treatment and passing all of them through a 45μm mesh sieve is subjected to heat treatment at 200°C for 4 hours in an atmospheric environment, except for this In addition, the phosphor particles of Comparative Example 2 were obtained through the same raw material input amount and procedures as those of Comparative Example 1.

(Example 1) For the phosphor powder obtained by decomposing the agglomerates by applying hydrofluoric acid treatment and passing all of them through a 45μm mesh sieve, heat treatment at 250°C for 4 hours in an atmospheric environment, except for this In addition, the phosphor particles of Example 1 were obtained through the same amount of input of raw materials and procedures as in Comparative Example 1.

(Example 2) The phosphor powder obtained by decomposing agglomerates by applying hydrofluoric acid treatment and passing all of them through a 45μm mesh sieve is subjected to a heat treatment at 300°C for 4 hours in an atmospheric environment, except for this In addition, the phosphor particles of Example 2 were obtained through the same amount of input of raw materials and procedures as in Comparative Example 1.

(Comparative example 3) For the phosphor powder obtained by decomposing agglomerates by applying hydrofluoric acid treatment and passing all through a 45μm sieve, heat treatment at 400°C for 4 hours in an atmospheric environment, except for this In addition, the phosphor particles of Comparative Example 3 were obtained through the same amount of input of raw materials and procedures as in Comparative Example 1.

For the phosphor particles obtained in Examples 1, 2, and Comparative Examples 1 to 3, the crystalline phase was investigated by powder X-ray diffraction measurement (XRD measurement) using Cu-Kα rays, and it was confirmed that the phosphor particles have a crystalline phase. Sr _a Li _b Eu _c Al ₃ N _4-d O _d represents the composition of the phosphor.

For the obtained phosphor particles, the total chemical wholly determined the composition of the crystal phase _{(i.e., Sr a Li b Eu c Al} 3 N 4-d O d) of the respective elements under the subscript a ~ d. Specifically, for Sr, Li, Al, and Eu systems, analysis results obtained by using an ICP emission spectrophotometer (manufactured by SPECTRO Co., Ltd., CIROS-120) were used, and for O and N systems, an oxygen and nitrogen analyzer (Horiba) was used. EMGA-920, manufactured by Mfg. Co., Ltd.), and calculate the subscripts a~d. The values of a~d of each phosphor particle are shown in Table 1.

(Analysis using X-ray diffraction method) For the obtained phosphor particles, an X-ray diffraction device (UltimaIV manufactured by Rigaku Corporation) and Cu-Kα rays were used, and the X-ray diffraction pattern measurement was performed under the following measurement conditions. In addition, the crystal structure of the phosphor particles was confirmed from the obtained X-ray diffraction pattern. (Measurement conditions) X-ray source: Cu-Kα rays (λ=1.54184Å), Output setting: 40kV･40mA Optical system: concentration method Detector: semiconductor detector Optical conditions during measurement: divergence grating=2/3° Scattering grating = 8mm Light receiving grating = open The position of the diffraction peak = 2θ (angle of diffraction) Measuring range: 2θ=20°~70° Scanning speed: 2 degrees (2θ)/sec, continuous scanning Scan axis: 2θ/θ Sample preparation: Load the powdered phosphor particles on the sample holder. The peak intensity is a value obtained by performing background correction.

In Examples 1, 2, and Comparative Example 3, the peak portion (maximum peak portion A) _{corresponding to SrAlF 5 was} confirmed in the range of 2θ of 24.5° or more and 25.5° or less. In Comparative Examples 1 and 2, no peak _{corresponding to SrAlF 5 was confirmed.} In Examples 1, 2, and Comparative Examples 1 to 3, the peak part (maximum peak part B) corresponding to SLAN was confirmed in the range of 2θ of 36.5° or more and 37.5° or less. _{Calculate I A} /I _B when the luminous intensity of the largest peak _A is I A and the luminous intensity of the _{largest peak B is I B.} The results are shown in Table 1.

In addition, in Examples 1, 2, and Comparative Example 3, 2θ was confirmed to correspond to AlF _{3 in} the range of 14° or more and 15° or less. For Comparative Example 1, 2θ was confirmed to correspond to (NH ₄ ) ₃ AlF _{6 in} the range of 16.5° or more and 17.5° or less. In Comparative Example 1, a small peak _{corresponding to (NH 4} ) ₃ AlF _{6 was observed.}

(Using XPS for surface analysis) For the obtained phosphor particles, surface analysis using XPS was performed. For Examples 1, 2, and Comparative Example 1, it can be confirmed that Al and F are present on the outermost surface of the phosphor particles, and Al and F are covalently bonded.

Based on the surface analysis results performed by XPS and the analysis performed by the above-mentioned X-ray diffraction method, the following contents are shown. In Examples 1 and 2, at least a part of the outermost surface of the phosphor particles is made of AlF ₃ and coated with the phosphor particles. The phosphor particles of Comparative Example 1 are surface-coated phosphor particles in which at least a part of the outermost surface of the phosphor particles is composed of (NH ₄ ) ₃ AlF _6.

[Table 1] unit Comparative example 1 Comparative example 2 Example 1 Example 2 Comparative example 3 Heat treatment °C no 200 250 300 400 Composition of phosphor particles (mole ratio) a 1.02 1.02 1.02 1 1.01 b 0.99 0.98 0.98 0.97 0.97 c 0.008 0.009 0.008 0.008 0.008 d 0.34 0.11 0.08 0.07 0.15 d/(a+d) 0.25 0.10 0.07 0.07 0.13 Covered part (NH ₄ ) ₃ AlF ₆ no AlF ₃ AlF ₃ ※ Diffraction peak Fluorescence intensity I _A from SrAlF ₅ - - 5.7 6.5 12.5 Fluorescence intensity from SLAN I _B 100 100 100 100 100 I _A /I _B - - 0.057 0.065 0.125 Diffuse reflectance at wavelength of 300nm % 76 77 75 73 69 Diffuse reflectance at peak wavelength % 93 94 93 89 86 The half-width of the peak wavelength in the range of 640~670nm nm 55 56 55 54 53 CIE x value 0.711 0.712 0.711 0.709 0.709 Fluorescence intensity ratio I ₁₀₀ /I ₀ % 45 96 97 100 85 I ₂₀₀ /I ₀ % ※ 92 96 99 76

In Table 1, "-" means unavailable, and "※" means not implemented.

The obtained phosphor particles were evaluated based on the following evaluation items.

(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. A standard reflector (spectralon) was used for baseline calibration, and a solid sample holder filled with the obtained phosphor particles was installed to measure the diffuse reflectance of light of 300nm and 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 phosphor particles are filled to make the surface of the concave light analysis tube smooth, and then an integrating sphere is installed. Use optical fiber to split blue monochromatic light with a wavelength of 455nm from the light source (Xe lamp) into this integrating sphere. The blue monochromatic light is used as the excitation light source to irradiate the sample of the phosphor, and the fluorescence spectrum of the sample is measured. Obtain the peak wavelength and peak half-width from the obtained spectrum data. In addition, the chromaticity x is the wavelength region information from 465nm to 780nm of the fluorescence spectrum information. According to JIS Z 8724:2015, the CIE chromaticity coordinate x value in the XYZ color system specified in JIS Z 8781-3:2016 is calculated. (Chromaticity x).

(Luminescence intensity ratio before and after the high-temperature and high-humidity test) For the phosphor particles obtained in Examples 1, 2, and Comparative Examples 1 to 3, the luminous intensity (I ₀ ) before the start of the high-temperature and high-humidity test was measured by the following procedure . Then, place it in an environment of 60°C and 90%RH for 100 hours or 200 hours (high temperature and high humidity test). _{The luminous intensity (I 100} ) after the 100-hour high-temperature and _{high-humidity test and the luminous intensity (I 200} ) after the 200-hour high-temperature and high-humidity test were measured by the following procedures. Using the obtained measured values, the luminous intensity ratio was calculated from the following formulas: I ₁₀₀ /I ₀ (%) and I ₂₀₀ /I _{0 (%).} The results of the luminous intensity ratio are shown in Table 1.

･Measurement procedure of luminous intensity A spectrofluorometer (manufactured by Hitachi Advanced Technology Co., Ltd., F-7000) calibrated with Rose Red B (Rhodamine B) and a secondary standard light source was used to measure the luminous intensity of the phosphor particles. Also, use the solid sample holder attached to the spectrofluorometer and use the fluorescence spectrum with an excitation wavelength of 455 nm. The peak wavelength of the fluorescence spectrum of the phosphor particles of each embodiment and each comparative example is 656 nm. The intensity value of the peak wavelength of the fluorescence spectrum is taken as the luminous intensity of the phosphor particles.

Compared with Comparative Examples 1 to 3, the phosphor particles of Examples 1 and 2 showed the result of suppressing the decrease in luminous intensity after the high temperature and high humidity test. Therefore, according to the phosphor particles of Examples 1 and 2, it is possible to achieve surface-coated phosphor particles with excellent luminous intensity characteristics in a high-temperature and high-humidity environment.

This application claims priority based on Japanese application Special Application No. 2019-102122 filed on May 31, 2019, and quotes all the contents disclosed here.

Claims (6)

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, Na and K, and M ³ is One or more elements selected from Eu, Ce and Mn, 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 AlF ₃ , so that the X of the surface-coated phosphor particle obtained by measuring with Cu-Kα rays In the ray diffraction pattern, the luminous intensity of the largest peak A in the range of 2θ above 23° and 26° is I _A , and the luminous intensity of the largest peak B in the range of 2θ above 36° and 39° When it is I _B , I _A and I _B meet I _A /I _B ≦0.10. The surface-coated phosphor particles of claim 1, wherein the M ¹ contains at least Sr, the M ² contains at least Li, and the M ³ contains at least Eu. For example, the surface of claim 1 or 2 is coated with phosphor particles, in which, The diffuse reflectance for light irradiation with a wavelength of 300 nm is over 56%, and the diffuse reflectance for light irradiation with the peak wavelength of the fluorescence spectrum is over 80%. For example, when the surface-coated phosphor particles of claim 1 or 2 are 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-height width is 45 nm or more and 60 nm or less. For example, when the surface-coated phosphor particles of claim 1 or 2 are 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 light-emitting device having: the surface-coated phosphor particles according to any one of claims 1 to 5, and a light-emitting element.