CN112888762A - Surface-coated phosphor particle, composite, and light-emitting device - Google Patents

Surface-coated phosphor particle, composite, and light-emitting device Download PDF

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CN112888762A
CN112888762A CN201980069479.5A CN201980069479A CN112888762A CN 112888762 A CN112888762 A CN 112888762A CN 201980069479 A CN201980069479 A CN 201980069479A CN 112888762 A CN112888762 A CN 112888762A
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phosphor
phosphor particles
conductivity
omega
coated
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近藤良祐
小林庆太
梶山亮尚
渡边真太郎
三谷骏介
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Denka Co Ltd
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    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7728—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing europium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
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Abstract

The surface-coated phosphor particle of the present invention comprises: phosphor particles composed of a nitrogen oxide phosphor or a nitride phosphor, and a coating layer provided on the surface of the phosphor particles and composed of a metal hydroxide or a metal oxide containing 1 or more elements selected from the group consisting of aluminum, titanium, zirconium, yttrium, and hafnium. The hot water extraction conductivity index [ Delta ] omega defined below of the surface-coated phosphor particles is 2.0mS/m or less. (method for calculating Hot Water extraction conductivity index) (1) measurement of conductivity omega of ion-exchanged Water at 25 ℃0. (2) Coating the surface with a phosphor1g of the particles were dispersed in 30ml of the ion-exchanged water, the solution was placed in a pressure-resistant vessel, heated at 150 ℃ for 16 hours, and 20ml of the ion-exchanged water was added thereto, and the conductivity Ω was measured in a state of being cooled to 25 ℃1. (3) Will have a conductivity omega1And electrical conductivity omega0Difference Δ Ω (═ conductivity Ω)1Electrical conductivity omega0) As a hot water extraction conductivity index Δ Ω.

Description

Surface-coated phosphor particle, composite, and light-emitting device
Technical Field
The present invention relates to surface-coated phosphor particles, a composite, and a light-emitting device.
Background
In recent years, a light-emitting device has been developed in which a semiconductor light-emitting element such as an LED and a phosphor that absorbs a part of light from the semiconductor light-emitting element and converts the absorbed light into wavelength-converted light having a long wavelength to emit light are combined. As the phosphor, a nitride phosphor and an oxynitride phosphor having a relatively stable crystal structure have attracted attention.
Patent document 1 discloses that the surface of a β sialon phosphor is covered with a metal hydroxide in order to improve the luminance of the β sialon phosphor.
Patent document 2 discloses a conventional technique in which the surface of phosphor particles is coated with a glass material in order to suppress hydrolysis of a sulfide-containing phosphor due to reaction with moisture in the air. Further, in order to point out that the coating film affects the dispersibility of the phosphor particles in the sealing material, a method of covering the surface of the phosphor particles with coating material particles containing a metal oxide in order to improve the dispersibility of the phosphor in the sealing material is disclosed.
Patent document 3 discloses that in order to improve the gas barrier property of a coating layer provided on the surface of phosphor particles, a glass frit attached to the surface of the phosphor particles is melted by heating, thereby forming a continuous coating film on the surface of the phosphor particles.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open No. 2014-197635
Patent document 2: japanese patent laid-open No. 2008-291251
Patent document 3: japanese laid-open patent publication No. 2009-13186
Disclosure of Invention
The inventors investigated the characteristics of a light-emitting device in which a composite obtained by sealing a phosphor with a sealing material was assembled together with an LED, and found that the emission intensity slightly decreased with the lapse of time. As a result of examining the cause of this phenomenon, it has been found that the moisture that has moved through the sealing material contacts the phosphor, whereby the metal component in the phosphor is ionized and eluted into the moisture, and the crystal structure of the phosphor gradually changes, whereby the wavelength conversion efficiency of the phosphor decreases, and the emission intensity of the light-emitting device decreases.
According to the present invention, there is provided a surface-coated phosphor particle comprising a phosphor particle comprising an oxynitride phosphor or a nitride phosphor and a coating layer provided on the surface of the phosphor particle and comprising a metal hydroxide or a metal oxide containing 1 or more elements selected from the group consisting of aluminum, titanium, zirconium, yttrium and hafnium, wherein a hot water extraction conductivity Δ Ω defined below is 2.0mS/m or less.
(method of calculating Hot Water extraction conductivity index)
(1) Measurement of conductivity omega of ion-exchanged Water at 25 deg.C0。
(2) 1g of the surface-coated phosphor particles was dispersed in 30ml of the ion-exchanged water, the solution was placed in a pressure-resistant vessel and heated at 150 ℃ for 16 hours, and 20ml of the ion-exchanged water was added thereto, and the conductivity Ω was measured in a state of being cooled to 25 ℃1。
(3) Will have a conductivity omega1And electrical conductivity omega0Difference Δ Ω (═ conductivity Ω)1Electrical conductivity omega0) As a hot water extraction conductivity index Δ Ω.
Further, according to the present invention, there is provided a composite comprising the surface-coated phosphor particles and a sealing material for sealing the surface-coated phosphor particles.
Further, according to the present invention, there is provided a light-emitting device including a light-emitting element that emits excitation light and the complex that converts the wavelength of the excitation light.
According to the present invention, elution of metal components constituting phosphor particles into moisture can be suppressed.
Drawings
The above objects, and other objects, features and advantages will become more apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings.
Fig. 1 is a schematic sectional view showing a structure of a light-emitting device according to an embodiment.
FIG. 2 is an SEM image of the surface-coated phosphor particles of example 1.
FIG. 3 is an SEM image of the surface-coated phosphor particles of example 2.
Fig. 4 is an SEM image of the phosphor particles of comparative example 1.
Detailed Description
The present inventors have conducted extensive studies on a technique for suppressing elution of a metal component constituting a phosphor particle in the form of ions in water, and as a result, have found that it is important to highly control the form of a coating layer formed on the surface of the phosphor particle, and particularly, a material constituting the coating layer is selected, thereby completing the present invention. Hereinafter, embodiments of the present invention will be described in detail.
(surface-coated phosphor particles)
The surface-coated phosphor particles of the embodiment include phosphor particles and a coating layer provided on the surface of the phosphor particles. The following describes each configuration of the surface-coated phosphor particles according to the present embodiment.
(phosphor particles)
The phosphor particles are composed of an oxynitride phosphor or a nitride phosphor.
Examples of the oxynitride fluorescent material include an α -type sialon fluorescent material containing Eu and a β -type sialon fluorescent material containing Eu.
The Eu-containing alpha-sialon phosphor is represented by the general formula: mxEuySi12－(m+n)Al(m+n)OnN16－nAnd (4) showing. In the above general formula, M is at least 1 element including Ca selected from Li, Mg, Ca, Y and lanthanoids (excluding La and Ce), and when the valence of M is a, ax +2Y is M, x is 0 < x.ltoreq.1.5, 0.3. ltoreq. M < 4.5, and 0 < n < 2.25.
The Eu-containing beta-sialon phosphor is divalent europium (Eu) as a light emission center2+) Solid solubility is represented by the general formula: si6－zAlzOzN8－zA phosphor obtained from a β -type sialon represented by (z is 0.005 to 1).
Examples of the nitride phosphor include a CASN phosphor containing Eu and a SCASN phosphor containing Eu.
The Eu-containing CASN phosphor is represented by the formula CaAlSiN3：Eu2+Showing that Eu is2+A red phosphor containing a crystal of an alkaline earth silicon nitride as a base as an activator. Note that the definition of the CASN phosphor containing Eu in the present specification does not include the SCASN phosphor containing Eu.
The Eu-containing SCASN phosphor is represented by, for example, the formula (Sr, Ca) AlSiN3：Eu2+Showing that Eu is2+A red phosphor containing a crystal of an alkaline earth silicon nitride as a base as an activator.
The phosphor particles of the present embodiment are preferably composed of the above-described α -sialon phosphor containing Eu, β -sialon phosphor containing Eu, CASN phosphor containing Eu, or SCASN phosphor containing Eu.
The particle size of the phosphor particles is not particularly limited, and is appropriately adjusted so as to obtain dispersibility in a sealing material and desired wavelength conversion efficiency, which will be described later.
(cover layer)
In the present embodiment, a coating layer made of a metal hydroxide or a metal oxide containing 1 or more elements selected from aluminum, titanium, zirconium, yttrium, and hafnium is provided on the surface of the phosphor particle. The metal hydroxide or metal oxide is excellent in transparency and stability, and among them, aluminum hydroxide or aluminum oxide is preferably used from the viewpoints of water-blocking property, cost-suppressing property, covering property with phosphor particles, and the like.
The coating layer may be an aggregate of a plurality of particles made of metal hydroxide or metal oxide, but is preferably a continuous coating layer made of metal hydroxide or metal oxide and continuously coating the phosphor particles. Here, the continuous coating layer is a layered structure formed by a metal hydroxide or a metal oxide as a continuous film, and is a structure different from an aggregate formed by a plurality of particles being tightly aggregated as in the invention described in patent document 2. The continuous covering layer may have a concavo-convex structure formed with a plurality of non-penetrating recesses.
The surface coverage of the phosphor particles by the coating layer is preferably 50% or more, and more preferably 70% or more. By setting the surface coverage of the coating layer as described above, the amount of the metal component of the phosphor particles eluted as ions can be further suppressed. The coating layer preferably covers the entire surface of the phosphor particles.
The surface coverage of the cover layer can be evaluated by X-ray photoelectron spectroscopy (XPS) measurement. Specifically, focusing on Si, which is an element contained in the phosphor particles but not contained in the metal hydroxide or metal oxide constituting the coating layer, the content of Si in the surface of the phosphor particles (atm%: atomic%) was obtained by XPS measurement. When the content of Si in phosphor particles that are not covered with a metal hydroxide or a metal oxide is a1 and the content of Si in phosphor particles that are the subject of calculation of the surface coverage is a2 without performing surface treatment described later, the surface coverage of the covering layer can be calculated by the following formula.
Surface coverage (%) - (a 1-a 2)/a1 × 100
The lower limit of the thickness of the coating layer is preferably 0.01 μm or more, and more preferably 0.1 μm or more. The upper limit of the thickness of the coating layer is preferably 10 μm or less, and more preferably 5 μm or less. By setting the thickness of the coating layer to 0.01 μm or more, the amount of elution of the metal component contained in the phosphor particles in the form of ions can be further suppressed. Further, by setting the thickness of the coating layer to 10 μm or less, it is possible to suppress a decrease in the wavelength conversion efficiency of the surface-coated phosphor particles.
(Hot Water extraction conductivity index)
The hot water extraction conductivity index Δ Ω of the surface-coated phosphor particles of the present embodiment, which is defined below, is 2.0mS/m or less.
(method of calculating Hot Water extraction conductivity index)
(1) Measurement of conductivity omega of ion-exchanged Water at 25 deg.C0。
(2) Dispersing 1g of surface-coated phosphor particles in 30ml of the ion-exchanged water by using a dispersing device such as an ultrasonic disperser, placing the mixture in a pressure-resistant container, heating at 150 ℃ for 16 hours, adding 20ml of ion-exchanged water, and measuring the conductivity omega in a state of cooling to 25 ℃1。
(3) Will have a conductivity omega1And electrical conductivity omega0Difference Δ Ω (═ conductivity Ω)1Electrical conductivity omega0) As a hot water extraction conductivity index Δ Ω.
The hot water extraction conductivity index is an index indicating that the smaller the value is, the smaller the amount of metal ions eluted from the phosphor particles into water is.
(method for producing surface-coated phosphor particles)
An example of a method for producing surface-coated phosphor particles having a coating layer made of a metal oxide includes a production method including the steps of: (1) a step of forming a coating layer made of a material (particle or the like) containing a metal hydroxide on the surface of the phosphor particle, and (2) a step of converting the coating layer into a continuous coating layer while converting the metal hydroxide into a metal oxide by applying heat treatment to obtain a surface-coated phosphor particle having a continuous coating layer containing a metal oxide. In this production method, it is important to densely coat the coating layer formed of the particles containing the metal hydroxide so that the coating layer can be converted into a continuous coating layer by the heat treatment.
The following describes 3 examples of the production method examples 1 to 3 as a method for producing such surface-coated phosphor particles.
[ production method example 1]
Production method example 1 includes a slurry preparation step, a stirring step, a pH adjustment step, a stirring, cleaning, and filtration step, a drying step, and a heating step. The details of each step are described below.
(slurry preparation Process)
Phosphor powder, ion-exchanged water and a substance containing a metal hydroxide are mixed in appropriate amounts, respectively, to prepare a phosphor-containing paste. The pH of the slurry obtained here is preferably within a range in which both the surface potential of the phosphor particles and the surface potential of the metal hydroxide-containing substance are positive values. The surface potentials of the phosphor particles and the metal hydroxide-containing substance can be measured by a zeta potential measuring device, for example. When aluminum hydroxide is used as the substance containing a metal hydroxide, the aluminum hydroxide may be used in the form of a sol (which may be conventionally referred to as an alumina sol) or an aqueous aluminum hydroxide solution.
(stirring step)
The slurry obtained in the slurry preparation step is stirred using a stirring method such as a stirrer or a stirring device so that the phosphor powder and the metal hydroxide-containing substance are sufficiently dispersed.
(pH adjustment step)
In the pH adjustment step, the pH is adjusted to 9 or more by adding dropwise the alkaline agent to the obtained slurry at a predetermined dropping rate. As the alkaline agent, NH may be mentioned3Aqueous alkaline solutions such as aqueous solutions and aqueous NaOH solutions. The substance containing metal hydroxide during the increase of pH by addition of alkaline agentThe surface potential of the substance is positive, and the surface potential of the phosphor particles is negative. This makes it easy to attach a substance containing a metal hydroxide densely to the surface of the phosphor particles.
Specifically, when β -type sialon phosphor particles are used as the phosphor particles and an alumina sol is used as the substance containing a metal hydroxide, the pH is 6.5 or more, the surface potential of aluminum hydroxide is positive, and the surface potential of β -type sialon phosphor particles is negative. Accordingly, since electrostatic attraction acts between the both, a substance containing aluminum hydroxide is easily adhered to the surface of the β -type sialon phosphor particle.
In the pH adjustment step, when an alkaline aqueous solution is used as the alkaline agent, the thickness and the surface coverage of the metal hydroxide-containing substance adhering to the surface of the phosphor particles can be controlled by adjusting the concentration, the dropping speed, and the dropping time of the alkaline aqueous solution.
(stirring, washing, filtration step)
The slurry obtained in the pH adjustment step is stirred by a stirring method such as a stirrer so as to sufficiently disperse the phosphor particles, and is washed with a washing liquid such as ion-exchanged water. Then, the phosphor powder (phosphor particles covered with a substance containing a metal hydroxide) is taken out by a filtration method such as suction filtration.
(drying Process)
The obtained phosphor powder is subjected to a heating treatment for a predetermined time so as to be sufficiently dried, thereby obtaining a phosphor powder composed of a plurality of phosphor particles whose surfaces are tightly covered with a material containing a metal hydroxide.
(heating step)
The obtained phosphor powder is subjected to heat treatment, whereby the layer containing the metal hydroxide, which tightly covers the surface of the phosphor particles, is oxidized to become a metal oxide, and a continuous film-like form such as a continuous coating layer made of the metal oxide is formed. The temperature at the time of heating the phosphor powder is preferably 500 ℃ or more and 1000 ℃ or less, and particularly when an alumina sol is used as the material containing a metal hydroxide, the heating temperature is preferably 500 ℃ or more and 600 ℃ or less. Through the above steps, surface-coated phosphor particles in which a continuous coating layer made of a metal oxide is formed on the surfaces of the phosphor particles are produced.
[ production method example 2]
Production method example 2 includes a slurry preparation step, a stirring, cleaning, and filtering step, a drying step, and a heating step. In production method example 1, the pH was adjusted by adding an alkaline agent after the stirring step, but in production method example 2, the pH was adjusted by adding an alkaline agent in the slurry preparation step.
If the pH is adjusted by adding an alkaline agent after the stirring step as in production method example 1, the coating layer formed of the substance containing the metal hydroxide can be made denser. The rate of addition of the alkaline agent can be adjusted, and the density of the coating can be further improved. By forming such a dense coating layer, a continuous coating layer can be stably obtained by the subsequent heat treatment.
On the other hand, if the pH is adjusted in the slurry preparation step as in production method example 2, the production step can be shortened.
[ production method example 3]
Production method example 3 includes a slurry preparation step, a stirring step, a pH adjustment step, a stirring, cleaning, and filtration step, a drying step, and a heating step. The details of each step are described below.
In production method example 1 and production method example 2, a substance containing a metal hydroxide was used as a starting material for the continuous covering layer, but in production method example 3, a precursor substance of a metal hydroxide was used as a starting material for the continuous covering layer.
(slurry preparation Process)
In this example, phosphor powder, ion-exchanged water, and precursor materials of metal hydroxide were mixed in appropriate amounts to prepare phosphor-containing pastes. In the case where the metal hydroxide is aluminum hydroxide, sodium aluminate is used as its precursor substance. The obtained slurry is usually strongly alkaline, and specifically, the pH is preferably 12 or more, more preferably 13 or more. By adding an acid such as hydrochloric acid or sulfuric acid to the slurry, a metal hydroxide is precipitated. Thus, a phosphor-containing paste containing a phosphor powder, ion-exchanged water and a metal hydroxide was obtained. The pH of the phosphor-containing slurry obtained here is in a range where both the surface potential of the phosphor particles and the surface potential of the metal hydroxide are negative values, and specifically, the pH is preferably 11 or more, and more preferably 12 or more.
(stirring step)
The slurry obtained in the slurry preparation step is stirred using a stirring method such as a stirrer or a stirring device so that the phosphor powder and the metal hydroxide are sufficiently dispersed.
(pH adjustment step)
In the pH adjustment step, an acid such as hydrochloric acid or sulfuric acid is added dropwise to the obtained slurry at a predetermined dropping rate, thereby adjusting the pH to 9 or less. In the process of lowering the pH value by adding an acid, one of the surface potential of the metal hydroxide and the surface potential of the phosphor particles is positive, and the other surface potential is negative, so that the metal hydroxide is easily adhered densely to the surface of the phosphor particles.
Specifically, when β -type sialon phosphor particles are used as the phosphor particles and aluminum hydroxide is precipitated from a slurry containing sodium aluminate, the pH is 10 or less, the surface potential of the aluminum hydroxide is positive, and the surface potential of the β -type sialon phosphor particles is negative. Thus, since electrostatic attraction acts between the both, aluminum hydroxide is easily adhered to the surface of the β -type sialon phosphor particles.
In the pH adjustment step, the concentration of the acid to be dropped into the slurry, the dropping speed, and the dropping time are adjusted, whereby the thickness and the surface coverage of the metal hydroxide adhering to the surface of the phosphor particle can be controlled.
After the pH adjustment, the stirring step, the pH adjustment step, the stirring, cleaning, and filtering steps, the drying step, and the heating step were performed in the same manner as in production method example 1 to produce surface-coated phosphor particles in which a continuous coating layer made of a metal oxide was formed on the surfaces of the phosphor particles.
In production method example 3, after adding an acid in the slurry preparation step (step of precipitating a metal hydroxide from a precursor material), a stirring step is performed, and further an acid is added to adjust the pH. As a method different from this, a slurry preparation step and a stirring step may be performed in parallel, and an acid may be continuously added from the slurry preparation step to adjust the pH so that one of the surface potential of the metal hydroxide and the surface potential of the phosphor particles is positive and the other surface potential is negative.
Here, the hot water extraction conductivity index can be controlled by appropriately selecting the kind and amount of the metal oxide, the method of attaching the metal oxide to the surface of the phosphor particles, and the like, for example. Among them, examples of the elements for bringing the hot water extraction conductivity index into a desired numerical range include, for example, pH adjustment conditions for causing a substance containing a metal hydroxide to adhere closely to the surface of the phosphor particles, heating conditions for converting the substance containing a metal hydroxide adhering closely to the surface of the phosphor particles into a metal oxide, and the like.
According to the surface-coated phosphor particles of the present embodiment, the coating layer made of a metal oxide is formed on the surface of the phosphor particles so that the hot water extraction conductivity index Δ Ω is 2.0mS/m or less, whereby when moisture is present around the surface-coated phosphor particles, the moisture is prevented from entering the inside of the phosphor particles. As a result, the amount of ions eluted by moisture is reduced, and deterioration of the phosphor particles is suppressed.
(light-emitting device)
Fig. 1 is a schematic sectional view showing a structure of a light-emitting device according to an embodiment. As shown in fig. 1, the light-emitting device 10 includes a light-emitting element 20, a heat spreader 30, a case 40, a1 st lead frame 50, a2 nd lead frame 60, a bonding wire 70, a bonding wire 72, and a composite 80.
The light emitting element 20 is attached to a predetermined region on the upper surface of the heat sink 30. By mounting the light emitting element 20 on the heat sink 30, the heat dissipation of the light emitting element 20 can be improved. Instead of the heat sink 30, a package substrate may be used.
The light emitting element 20 is a semiconductor element that emits excitation light. As the light emitting element 20, for example, an LED chip that generates light having a wavelength of 300nm or more and 500nm or less corresponding to blue light from near ultraviolet can be used. One electrode (not shown) provided on the upper surface side of the light-emitting element 20 is connected to the surface of the 1 st lead frame 50 via a bonding wire 70 such as a gold wire. The other electrode (not shown) formed on the upper surface of the light-emitting element 20 is connected to the surface of the 2 nd lead frame 60 via a bonding wire 72 such as a gold wire.
The case 40 is formed with a substantially funnel-shaped recess portion whose diameter gradually increases from the bottom surface toward the upper portion. A light emitting element 20 is provided on the bottom surface of the recess. The wall surface of the recess surrounding the light emitting element 20 functions as a reflection plate.
The concave portion having a wall surface formed by the case 40 is filled with the composite 80. The composite 80 is a wavelength conversion member for converting the wavelength of the excitation light emitted from the light emitting element 20 to a long wavelength. The composite 80 of the present embodiment is used, and the surface-coated phosphor particles 82 of the present embodiment are dispersed in a sealing material 84 such as a resin. The light-emitting device 10 emits a mixed color of light of the light-emitting element 20 and light generated from the surface-coated phosphor particles 82 that absorb and excite the light of the light-emitting element 20. The light-emitting device 10 preferably emits white light by color mixing of light from the light-emitting element 20 and light generated from the surface-coated phosphor particles 82.
In the light-emitting device 10 of the present embodiment, by covering the surface of the phosphor particles 82 with hot water having an extraction conductivity index Δ Ω of 2.0mS/m or less as described above, it is possible to suppress elution of ions caused by moisture from the phosphor particles into the sealing material 84, and further, to suppress a decrease in the emission intensity of the light-emitting device 10, thereby improving the reliability of the light-emitting device 10.
The embodiments of the present invention have been described above, but these are examples of the present invention, and various configurations other than the above may be adopted.
For example, although fig. 1 illustrates a surface mount type LED as the light emitting device of the embodiment, the light emitting device of the embodiment may be a shell type LED.
The embodiments of the present invention have been described above, but these are examples of the present invention, and various configurations other than the above may be adopted.
Examples
The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples.
Production example 1. beta. sialon
95.43 mass% of an alpha-type silicon nitride powder (SN-E10 grade, oxygen content 1.0 mass%) manufactured by Utsu corporation, 3.04 mass% of an aluminum nitride powder (F grade, oxygen content 0.8 mass%) manufactured by Tokuyama corporation, 0.74 mass% of an aluminum oxide powder (TM-DAR grade) manufactured by Dalmatian chemical corporation, and 0.79 mass% of an europium oxide powder (RU grade) manufactured by shin-Etsu chemical industry corporation were mixed by a V-type mixer (S-3 manufactured by Katsui Chemicals corporation), and all of them were passed through a sieve having a mesh size of 250 μm to remove aggregates, thereby obtaining a raw material mixed powder. The mixing ratio (% by mass) herein is represented by the general formula of β -sialon: si6－zAlzOzN8－zWherein the europium oxide is not included, and the Si/Al ratio is calculated to be 0.25.
200g of the raw material mixed powder having the composition of the above mixing ratio was charged in a cylindrical boron nitride container (N-1 grade, manufactured by electrochemical Co., Ltd.) with a lid having an inner diameter of 10cm and a height of 10cm, and heat treatment was performed at 2000 ℃ for 12 hours in a pressurized nitrogen atmosphere at 0.8MPa by using an electric furnace of a carbon heater. Since the sample after the heat treatment was in the form of a lump which was gradually aggregated, the lump was coarsely pulverized by a hammer and then pulverized by a supersonic jet pulverizer (PJM-80 SP, manufactured by Nippon Pneumatic Kogyo). The crushing conditions were a sample feed rate of 50 g/min and a crushing air pressure of 0.3 MPa. The pulverized powder was passed through a sieve having a mesh size of 45 μm. The sieve passage rate was 95%.
20g of the pulverized powder passing through the sieve was charged into a cylindrical boron nitride container with a lid having an inner diameter of 5cm and a height of 3.5cm, and annealing treatment was performed at 1500 ℃ for 8 hours in an argon atmosphere at atmospheric pressure using an electric furnace with a carbon heater. For the powder subjected to the annealing treatment, 1: 1 mixed acid, and soaking for 30 minutes at 75 ℃. The powder after the acid treatment was directly precipitated, decantation was repeated to remove the supernatant and the fine powder until the pH of the solution became 5 or more and the supernatant became transparent, and the finally obtained precipitate was filtered and dried to obtain phosphor particles (β type sialon phosphor powder) of production example 1. The powder X-ray diffraction measurement was carried out, and as a result, the crystal phase present was a single phase of the beta-type sialon. The contents of Si, A1 and Eu were determined to be 57.7, 2.29, and 0.62 mass%, respectively, by ICP emission spectroscopy. The z value calculated from Si and Al contents was 0.24. The compounding ratio of production example 1 is shown in table 1.
[ Table 1]
TABLE 1
Figure BDA0003030875190000111
(example 1)
The phosphor particles (β type sialon phosphor powder) of production example 1 were subjected to surface treatment by the following procedure.
[ surface treatment ]
(1) 10g of the phosphor particles of production example 1, 150ml of ion-exchanged water, and 7.11g of alumina sol (alumina sol 520-A, manufactured by Nissan chemical Co., Ltd.) were mixed to prepare a slurry. The pH of the resulting slurry was 4.1. When the surface potential of aluminum hydroxide and the surface potential of the phosphor particles were measured at pH4.1 using a zeta potential measuring apparatus, the surface potential of aluminum hydroxide was 44mV and the surface potential of the phosphor particles was 16mV, respectively.
(2) The slurry was stirred for 15 minutes using a stirrer.
(3) 0.05 wt% ammonia water was slowly dropped into the slurry, and the pH was adjusted to 9 after 3 minutes of dropping time. When the surface potential of aluminum hydroxide and the surface potential of the phosphor particles were measured at pH 9 using a zeta potential measuring apparatus, the surface potential of aluminum hydroxide was 13mV and the surface potential of the phosphor particles was 25mV, respectively.
(4) The slurry was stirred for 60 minutes using a stirrer, washed with ion-exchanged water, and then subjected to suction filtration to obtain phosphor powder.
(5) The obtained phosphor powder was dried at 105 ℃ for 15 hours.
(6) The phosphor powder after the drying treatment was subjected to a heating treatment at 600 ℃ for 1 hour using an electric furnace, to obtain surface-coated phosphor particles of example 1.
The surface-coated phosphor particles of example 1 were observed by a Scanning Electron Microscope (SEM). FIG. 2 is an SEM image of the surface-coated phosphor particles of example 1. As shown in fig. 2, it was confirmed that the continuous coating layer was formed by continuously coating the surface of the phosphor particles with alumina, instead of dispersing alumina on the surface of the phosphor particles.
(example 2)
The phosphor particles of production example 1 were surface-treated in the same manner as in example 1 except that 4.74g of AERODISP W630 (manufactured by Evonik Resource Efficiency GmbH) was added instead of the alumina sol of the above-described surface treatment (1) to obtain a slurry having a pH of 5.0, and the surface-coated phosphor particles of example 2 were prepared. When the surface potential of aluminum hydroxide and the surface potential of the phosphor particles were measured at pH5.0 using a zeta potential measuring apparatus, the surface potential of aluminum hydroxide was 42mV and the surface potential of the phosphor particles was 11mV, respectively.
The surface-coated phosphor particles of example 2 were observed by SEM. FIG. 3 is an SEM image of the surface-coated phosphor particles of example 1. As shown in fig. 3, it was confirmed that the continuous coating layer was formed by continuously coating the surface of the phosphor particles with alumina, instead of dispersing alumina on the surface of the phosphor particles.
Comparative example 1
The phosphor particles of production example 1 were not subjected to the surface treatment described above, and comparative example 1 was defined. The phosphor particles of comparative example 1 were observed by SEM. Fig. 4 is an SEM image of the phosphor particles of comparative example 1. As shown in fig. 4, the surfaces of the phosphor particles of comparative example 1 were all exposed.
[ method for calculating Hot Water extraction conductivity index ]
The hot water extraction conductivity indexes of the surface-coated phosphor particles of each example and the phosphor particles of comparative example 1 were calculated in the following manner. The obtained results are shown in table 2 for hot water extraction conductivity index.
(1) Measurement of conductivity omega of ion-exchanged Water at 25 deg.C0。
(2) 1g of surface-coated phosphor particles (or phosphor particles) was dispersed in 30ml of the ion-exchanged water by an ultrasonic disperser, the mixture was heated at 150 ℃ for 16 hours in a pressure-resistant vessel, 20ml of the ion-exchanged water was added, and the electric conductivity Ω was measured in a state of being cooled to 25 ℃1。
(3) Will have a conductivity omega1And electrical conductivity omega0Difference Δ Ω (═ conductivity Ω)1Electrical conductivity omega0) As a hot water extraction conductivity index Δ Ω.
[ reliability test ]
The reliability test of the LED package carrying the phosphor particles of each example and the phosphor particles of comparative example 1 was evaluated in the following manner. The results obtained by the reliability test are shown in table 2.
The LED package uses a device according to the structure of the light emitting device shown in fig. 1.
The phosphor is mounted on the LED package as follows: after the lead frame was wire-bonded to the electrode provided on the top surface of the LED at the bottom of the concave part of the case, phosphor particles mixed with a liquid silicone resin (OE6656, manufactured by Toray-Dow Coming co., ltd.) were injected into the concave part of the case from a micro syringe. After the phosphor particles were mounted, they were cured at 120 ℃ and then subjected to post-curing at 110 ℃ for 10 hours to seal. The LED used had an emission peak wavelength of 448nm and a chip size of 1.0 mm. times.0.5 mm.
The LED package obtained as described above and having the phosphor particles of each example and the phosphor particles of comparative example 1 mounted thereon was measured for a luminous flux as an initial value L0. After leaving at 85 ℃ and 85% RH for 500 hours, the sample was taken out and dried at room temperature, and the light beam L1 at that time was measured to calculate the reliability coefficient M (L1/L0 × 100). The qualified condition of the reliability test is that the reliability coefficient M is more than 95%. This is a value that cannot be achieved by highly reliable phosphor particles. It was confirmed that the LED packages having phosphor particles coated on the surfaces thereof according to examples 1 and 2 were mounted thereon and the above-mentioned acceptable conditions were satisfied. This result is presumed to be because in the surface-coated phosphor particles of examples 1 and 2, the metal components constituting the phosphor particles are inhibited from being eluted into the moisture by the coating layer formed on the surface of the phosphor particles.
[ Table 2]
TABLE 2
Example 1 Example 2 Comparative example 1
Phosphor particle Production example 1 Production example 1 Production example 1
Hot water extraction conductivity index delta omega (mS/m) 0.85 0.33 2.13
Reliability factor M (%) 97 96 93
The present application claims priority based on japanese application No. 2018-200304, filed 24.10.2018, the disclosure of which is incorporated herein in its entirety.

Claims (6)

1. A surface-coated phosphor particle is provided with:
phosphor particles composed of an oxynitride phosphor or a nitride phosphor, and
a coating layer which is provided on the surface of the phosphor particles and is composed of a metal hydroxide or a metal oxide containing 1 or more elements selected from the group consisting of aluminum, titanium, zirconium, yttrium, and hafnium;
a hot water extraction conductivity index [ Delta ] [ omega ] defined below is 2.0mS/m or less,
the calculation method of the hot water extraction conductivity index comprises the following steps:
(1) measurement of conductivity omega of ion-exchanged Water at 25 deg.C0，
(2) 1g of the surface-coated phosphor particles was dispersed in 30ml of the ion-exchanged water, the solution was placed in a pressure-resistant vessel and heated at 150 ℃ for 16 hours, and 20ml of the ion-exchanged water was added thereto, and the conductivity Ω was measured in a state of being cooled to 25 ℃1，
(3) Will have a conductivity omega1And electrical conductivity omega0Difference Δ Ω (═ conductivity Ω)1Electrical conductivity omega0) As a hot water extraction conductivity index Δ Ω.
2. The surface-coated phosphor particle according to claim 1, wherein the coating layer is a continuous coating layer continuously coating the surface of the phosphor particle.
3. The surface-coated phosphor particle according to claim 1 or 2, wherein the coating layer is composed of aluminum hydroxide or aluminum oxide.
4. The surface-coated phosphor particles according to any one of claims 1 to 3, wherein the phosphor particles are composed of an α -type sialon phosphor containing Eu, a β -type sialon phosphor containing Eu, a CASN phosphor containing Eu, or a SCASN phosphor containing Eu.
5. A composite body is provided with: the surface-coated phosphor particles according to any one of claims 1 to 4, and a sealing material for sealing the surface-coated phosphor particles.
6. A light-emitting device is provided with:
a light emitting element emitting excitation light, and
the complex of claim 5 that converts the wavelength of the excitation light.
CN201980069479.5A 2018-10-24 2019-10-04 Surface-coated phosphor particle, composite, and light-emitting device Pending CN112888762A (en)

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