JP2012062439A - Phosphor, method of manufacturing the same, and light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a phosphor in which strontium carbonate is used as a strontium compound, and which can thereby form a phosphor of an europium-activated sialon structure with a predetermined composition and structure, and to provide the phosphor, and to provide a light-emitting device.SOLUTION: The method of manufacturing a phosphor includes: a first baking step in which a first raw material mixture containing a strontium carbonate, silicon nitride, and europium oxide is baked under the H-containing gas atmosphere at 1,000°C-1,800°C to obtain a first baked product; and a second baking step in which a second raw material mixture containing the cracking object of the first baked product is baked at 1,400°C-2,200°C under the N-containing gas atmosphere to obtain the phosphor.

Description

  Embodiments described herein relate generally to a phosphor, a manufacturing method thereof, and a light emitting device.

  The phosphor powder is used for a light emitting device such as a light emitting diode (LED). The light emitting device includes, for example, a semiconductor light emitting element that is arranged on a substrate and emits light of a predetermined color, and a phosphor that emits visible light when excited by light such as ultraviolet light and blue light emitted from the semiconductor light emitting element. A light emitting part including powder in a transparent resin cured product which is a sealing resin.

  For example, GaN, InGaN, AlGaN, InGaAlP or the like is used as the semiconductor light emitting element of the light emitting device. Examples of the phosphor of the phosphor powder include a blue phosphor, a green phosphor, and a yellow phosphor that are excited by light emitted from the semiconductor light emitting element and emit blue light, green light, yellow light, and red light, respectively. A phosphor, a red phosphor or the like is used.

The light emitting device can adjust the color of the emitted light by including various phosphor powders such as a red phosphor in the sealing resin. That is, by using a combination of a semiconductor light emitting element and a phosphor powder that absorbs light emitted from the semiconductor light emitting element and emits light in a predetermined wavelength region, the light emitted from the semiconductor light emitting element and the phosphor powder are used. It becomes possible to emit light in the visible light region and white light by the action of the light emitted from.
Conventionally, a phosphor having a europium-activated sialon (Si—Al—O—N) structure containing strontium is known.

International Publication No. 2007/105631

  The europium-activated sialon-structured phosphor is usually obtained by firing a raw material mixture in which a strontium compound, a europium compound, a silicon compound, an aluminum compound and the like are mixed.

However, since strontium compounds are inexpensive and easily available, when using strontium carbonate suitable for industrial use, there is a case where a europium-activated sialon structure phosphor having a predetermined composition and structure cannot be obtained. That is, strontium carbonate SrCO ₃ has a large oxygen content of 3 mol of oxygen O relative to 1 mol of Sr. Therefore, when a raw material mixture containing strontium carbonate is fired, the oxygen O content of the fired body is within a predetermined composition range. There was a problem that it was easy to exceed.

  The present invention has been made in view of the above circumstances, and a phosphor manufacturing method and phosphor capable of producing a europium-activated sialon structure phosphor having a predetermined composition and structure using strontium carbonate as a strontium compound It is another object of the present invention to provide a light emitting device.

  The phosphor manufacturing method, the phosphor, and the light emitting device of the embodiment include a first firing step of firing a first raw material mixture containing strontium carbonate to obtain a first fired product, and a pulverized product of the first fired product. It has been completed by finding that a phosphor having a predetermined composition and structure can be obtained by performing a second firing step of firing a second raw material mixture to obtain a phosphor. .

Method for manufacturing a fluorescent embodiments is to solve the above problems, a first raw material mixture comprising a strontium carbonate and silicon nitride and the europium oxide, H ₂ containing gas atmosphere at 1000 ° C. to 1800 ° C. A phosphor is obtained by firing a first firing step of firing to obtain a first fired product and a second raw material mixture containing a pulverized product of the first fired product in an N ₂ -containing gas atmosphere at 1400 ° C. to 2200 ° C. And a second baking step to be obtained.

  In addition, the phosphor of the embodiment solves the above-described problems, and is a phosphor obtained by the manufacturing method, and the following general formula (1)

[Chemical 1]
General formula: (Sr _1-x , Eu _x ) _α Si _β Al _γ O _δ N _ω (1)
(Wherein x is 0 <x <1, α is 0 <α ≦ 4, and β, γ, δ and ω are values converted when α is 3, 9 <β ≦ 15, 1 ≦ γ ≦ 5, 0.5 ≦ δ ≦ 3, 10 ≦ ω ≦ 25)

It is characterized in that it emits green light when excited by ultraviolet light to blue light.

  Furthermore, the light emitting device of the embodiment solves the above-described problems. A substrate, a semiconductor light emitting element disposed on the substrate and emitting ultraviolet light to blue light, and a light emitting surface of the semiconductor light emitting element are provided. And a light emitting unit including a phosphor that emits visible light when excited by light emitted from the semiconductor light emitting element, and the phosphor includes the phosphor of the embodiment. .

An example of the emission spectrum of a light-emitting device.

  The phosphor manufacturing method, the phosphor, and the light emitting device of the embodiment will be described.

[Phosphor production method]
The phosphor manufacturing method includes a first firing step of firing a first raw material mixture containing strontium carbonate, silicon nitride, and europium oxide to obtain a first fired product, and a second method including a pulverized product of the first fired product. A second firing step of firing the raw material mixture to obtain a phosphor.

(First firing step)
The first firing step is a step of obtaining a first fired product by firing a first raw material mixture containing strontium carbonate, silicon nitride, and europium oxide in an atmosphere containing H _{2 at} 1000 ° C. to 1800 ° C.

<First raw material mixture>
The first raw material mixture is a mixture containing strontium carbonate SrCO ₃ , silicon nitride Si ₃ N ₄ and europium oxide Eu ₂ O ₃ .
The first raw material mixture may further contain silicon carbide SiC as a raw material for containing carbon in the finally obtained phosphor.
The first raw material mixture may further contain strontium chloride SrCl ₂ as a reaction accelerator as a fluxing agent.
The first raw material mixture usually does not contain an Al component. For this reason, the first fired product obtained by firing the first raw material mixture usually does not have a sialon structure.
The first raw material mixture is filled in a refractory crucible. As the refractory crucible, for example, a boron nitride crucible, a carbon crucible or the like is used.

<Baking conditions>
The first raw material mixture filled in the refractory crucible is fired. As the baking apparatus, an apparatus is used in which the composition and pressure of the internal baking atmosphere in which the refractory crucible is arranged, the baking temperature and the baking time are maintained under predetermined conditions. For example, an electric furnace is used as such a baking apparatus.
As a firing atmosphere in the first firing step, an H ₂ -containing gas is used. As the H ₂ -containing gas, for example, a mixed gas of H ₂ and N ₂ is used.
Of H ₂ containing H ₂ gas, at the time of firing the first raw material mixture, which is then acting as a reducing agent.

In general, when a phosphor powder is fired from a phosphor raw material mixture, an appropriate amount of oxygen O disappears from the phosphor raw material mixture containing excessive oxygen O with respect to the phosphor powder. A phosphor powder is obtained. At this time, if H ₂ is contained in the firing atmosphere and a reducing atmosphere is obtained, the degree of disappearance of oxygen O during firing increases.

For this reason, in this process, by using the H ₂ -containing gas as the firing atmosphere, the firing time is shorter when firing the first fired product from the first raw material mixture than when no H ₂ -containing gas is used. can do.

Even when the firing atmosphere is an N ₂ -containing gas, it is possible for N ₂ to eliminate an appropriate amount of oxygen O from the phosphor raw material mixture during firing. However, the degree of disappearance of oxygen O from the phosphor raw material mixture during firing is greater for H ₂ than for N ₂ .

In this step, an H ₂ -containing gas having a high degree of eliminating oxygen O from the phosphor raw material mixture during firing is used. This is because strontium carbonate SrCO ₃ has a higher oxygen O content than other strontium compounds such as strontium oxide SrO and strontium hydroxide Sr (OH) ₂ .

Containing H ₂ gas, if a mixed gas of _{H 2} gas or _{H 2} and _{N 2,} the molar ratio of _{H 2} and _{N 2} of the containing _{H 2} gas _is, H 2: _{N 2} is usually 10: 0 to 0.5: 9.5, preferably 8: 2 to 2: 8, and more preferably 6: 4 to 4: 6.
When the molar ratio of H ₂ and N ₂ in the H ₂ -containing gas is within the above range, that is, usually 10: 0 to 1: 9, the first fired product can be obtained in a short time firing.

The molar ratio of H ₂ and N ₂ of the containing H ₂ gas is the H ₂ and N ₂ which is continuously fed into the chamber of the calciner, H ₂ and the ratio of the flow rate the ratio of N ₂ And the mixture gas in the chamber is continuously discharged to achieve the above ratio, that is, usually 10: 0 to 1: 9.
It is preferable that the H ₂ -containing gas, which is a firing atmosphere, be circulated so as to form an air flow in the chamber of the firing apparatus because firing is performed uniformly.

The pressure of the H ₂ -containing gas that is the firing atmosphere is usually 0.01 MPa (approximately 0.1 atm) to 1.0 MPa (approximately 10 atm), preferably 0.05 MPa to 0.2 MPa.

  When the pressure of the firing atmosphere is less than 0.01 MPa, the phosphor produced in the next step using the first fired product obtained in this step is unlikely to have a predetermined composition, and the emission intensity of the phosphor powder is thereby reduced. May be weak.

When the pressure of the firing atmosphere exceeds 1.0 MPa, the firing conditions are not particularly changed even when the pressure is 1.0 MPa or less, which is not preferable because energy is wasted.
The firing temperature in the first firing step is 1000 ° C to 1800 ° C, preferably 1100 ° C to 1700 ° C, more preferably 1200 ° C to 1600 ° C.

When the firing temperature is in the range of 1000 ° C. to 1800 ° C., the first fired product suitable for obtaining a high-quality single crystal phosphor powder with few crystal structure defects in the subsequent second firing step can be obtained for a short time. Can be obtained at
When the firing temperature is less than 1000 ° C., the firing is not sufficiently performed, and it becomes difficult to obtain the first fired product.

When the firing temperature exceeds 1800 ° C., volatilization of the raw material components occurs, and a first fired product suitable for obtaining a high-quality single crystal phosphor powder with few crystal structure defects in the subsequent second firing step. It becomes difficult to obtain in a short time.
The firing time is usually 0.5 hours to 8 hours, preferably 2 hours to 6 hours, and more preferably 3 hours to 5 hours.

  When the firing time is less than 0.5 hours or more than 8 hours, the first firing suitable for obtaining a high-quality single crystal phosphor powder with few crystal structure defects in the subsequent second firing step It becomes difficult to get things.

  The firing time is preferably a short time within a range of 0.5 to 8 hours when the firing temperature is high, and a long time within a range of 0.5 to 8 hours when the firing temperature is low. It is preferable that

A first fired product is produced in the fire-resistant crucible after firing. The first fired product is usually in the form of a weak and solid lump. When the first fired product is lightly crushed using a pestle or the like, a crushed product of the first fired product is obtained.
The pulverized product obtained by pulverization is used as a raw material for the second firing step as the next work.

(Second firing step)
The second firing step is a step of obtaining a phosphor by firing the second raw material mixture including the pulverized product of the first fired product in an N ₂ -containing gas atmosphere at 1400 ° C. to 2200 ° C.

<Second raw material mixture>
The second raw material mixture is a mixture containing a pulverized product of the first fired product.
The first fired product and its pulverized product usually do not contain an Al component. For this reason, an aluminum compound is added and mixed with the crushed material of the 1st baked product in the 2nd raw material mixture.
Examples of the aluminum compound include one or more selected from aluminum oxide Al ₂ O ₃ and aluminum nitride AlN, and specifically include aluminum oxide, aluminum nitride, or a mixture thereof.

The second raw material mixture may further contain silicon carbide SiC as a raw material for containing carbon in the finally obtained phosphor. When the phosphor contains a small amount of carbon, a decrease in emission intensity at a high temperature of the phosphor tends to be suppressed.
The second raw material mixture may further contain strontium chloride SrCl ₂ as a reaction accelerator as a fluxing agent.
The second raw material mixture is filled in a refractory crucible. As the refractory crucible, for example, a boron nitride crucible, a carbon crucible or the like is used.

<Baking conditions>
The second raw material mixture filled in the refractory crucible is fired. As in the first firing step, the firing device is a device in which the composition and pressure of the firing atmosphere in which the refractory crucible is disposed, and the firing temperature and firing time are maintained under predetermined conditions. For example, an electric furnace is used as such a baking apparatus.
As the firing atmosphere, N ₂ -containing gas is used. As the N ₂ -containing gas, for example, N ₂ gas or a mixed gas of N ₂ and H ₂ is used.
H ₂ in the N ₂ -containing gas acts as a reducing agent when the phosphor powder is fired from the second raw material mixture.

In general, when a phosphor powder is fired from a phosphor raw material mixture, an appropriate amount of oxygen O disappears from the phosphor raw material mixture containing excessive oxygen O with respect to the phosphor powder. A phosphor powder is obtained. At this time, if H ₂ is contained in the N ₂ -containing gas, the firing atmosphere becomes a reducing atmosphere, and the degree of disappearance of oxygen O during firing increases.
Therefore, also in this process, if the H ₂ contained in the N ₂ containing gas, as compared to the case where the N ₂ containing gas does not contain H _2, to shorten the baking time.

N ₂ containing gas, if a mixed gas of _{N 2} gas or _{N 2} and _{H 2,,} the molar ratio of _{N 2} and _{H 2} in _{N 2} containing gas _is, N 2: _{H 2} is usually 10 : 0 to 1: 9, preferably 8: 2 to 2: 8, more preferably 6: 4 to 4: 6.

When the molar ratio of N ₂ and H ₂ in the N ₂ -containing gas is within the above range, that is, usually 10: 0 to 1: 9, a high-quality unit with few defects in the crystal structure can be obtained by firing in a short time. Crystalline phosphor powder can be obtained.

The molar ratio of N ₂ and H ₂ in N ₂ containing gas is a N ₂ and H ₂ which is continuously fed into the chamber of the calciner, N ₂ and the ratio of the flow rate the ratio of H ₂ And the mixture gas in the chamber is continuously discharged to achieve the above ratio, that is, usually 10: 0 to 1: 9.
It is preferable that the N ₂ -containing gas as the firing atmosphere be circulated in a chamber of the firing apparatus so as to form an air flow because firing is performed uniformly.

The pressure of the N ₂ -containing gas which is the firing atmosphere is usually 0.1 MPa (approximately 1 atm) to 1.0 MPa (approximately 10 atm), preferably 0.5 MPa to 0.8 MPa, more preferably 0.6 MPa to 0.8 MPa. is there.

  When the pressure of the firing atmosphere is less than 0.1 MPa, the composition of the phosphor powder obtained after firing is expressed by the general formula (1) by volatilization of a part of the constituent elements of the second raw material mixture charged in the crucible before firing. It is easy to be different from the Sr sialon green phosphor represented by), and there is a possibility that the emission intensity of the phosphor powder is weakened.

When the pressure of the firing atmosphere exceeds 1.0 MPa, the firing conditions are not particularly changed even when the pressure is 1.0 MPa or less, which is not preferable because energy is wasted.
A calcination temperature is 1400 degreeC-2200 degreeC normally, Preferably it is 1600 degreeC-1900 degreeC.
When the firing temperature is in the range of 1400 ° C. to 2200 ° C., a high-quality single crystal phosphor powder with few crystal structure defects can be obtained by firing in a short time.
If the firing temperature is less than 1400 ° C., the Sr sialon green phosphor represented by the general formula (1) may not be obtained.

When the firing temperature exceeds 2200 ° C., the composition of the phosphor powder obtained by increasing the degree of disappearance of N and O during firing tends to be different from the Sr sialon green phosphor represented by the general formula (1), For this reason, there exists a possibility that the emitted light intensity of fluorescent substance powder may become weak.
The firing time is usually 0.5 hours to 20 hours, preferably 2 hours to 10 hours, and more preferably 3 hours to 5 hours.

  When the firing time is less than 0.5 hours or more than 20 hours, the composition of the obtained phosphor powder tends to be different from that of the Sr sialon green phosphor represented by the general formula (1). There exists a possibility that the emitted light intensity of powder may become weak.

  The firing time is preferably a short time within a range of 0.5 hours to 20 hours when the firing temperature is high, and a long time within a range of 0.5 hours to 20 hours when the firing temperature is low. It is preferable that

  In the fire-resistant crucible after firing, a fired body made of phosphor powder is generated. The fired body is usually in the form of a weak and solid lump. When the fired body is lightly crushed using a pestle or the like, a phosphor powder is obtained. The phosphor powder obtained by crushing becomes a powder of Sr sialon green phosphor represented by the general formula (1).

[Green phosphor]
The phosphor is a green phosphor that emits green light when excited by ultraviolet light to blue light.
This green phosphor is obtained by the above phosphor production method, and has the following general formula (1)

[Chemical formula 2]
General formula: (Sr _1-x , Eu _x ) _α Si _β Al _γ O _δ N _ω (1)
(Wherein x is 0 <x <1, α is 0 <α ≦ 4, and β, γ, δ and ω are values converted when α is 3, 9 <β ≦ 15, 1 ≦ γ ≦ 5, 0.5 ≦ δ ≦ 3, 10 ≦ ω ≦ 25)

Is a phosphor that emits green light when excited by ultraviolet to blue light. Hereinafter, the europium-activated sialon phosphor containing Sr is also referred to as “Sr sialon green phosphor”. The crystal system of Sr sialon green phosphor is orthorhombic.

In the general formula (1), x is a number that satisfies 0 <x <1, preferably 0.025 ≦ x ≦ 0.5, and more preferably 0.25 ≦ x ≦ 0.5.
When x is 0, the fired body obtained in the firing step is not a phosphor, and when x is 1, the luminous efficiency of the green phosphor powder is low.

Further, the smaller the x is in the range of 0 <x <1, the easier it is for the emission efficiency of the green phosphor to decrease. Furthermore, as x becomes larger in the range of 0 <x <1, the concentration quenching is more likely to occur due to the excessive Eu concentration.
For this reason, x is preferably a number satisfying 0.025 ≦ x ≦ 0.5, and more preferably a number satisfying 0.25 ≦ x ≦ 0.5, even if 0 <x <1.

  In the general formula (1), the total subscript (1-x) α of Sr is a number satisfying 0 <(1-x) α <4. Further, the total subscript xα of Eu is a number satisfying 0 <xα <4. That is, in the general formula (1), the total subscripts of Sr and Eu are numbers exceeding 0 and less than 4, respectively.

In the general formula (1), β, γ, δ and ω are numerical values converted when α is 3.
In the general formula (1), β, which is a subscript of Si, is a number satisfying 9 <β ≦ 15 as a numerical value converted when α is 3.
In the general formula (1), γ, which is a subscript of Al, is a number satisfying 1 ≦ γ ≦ 5 as a numerical value converted when α is 3.
In the general formula (1), δ, which is a subscript of O, is a number satisfying 0.5 ≦ δ ≦ 3 when a value of α is 3.
In the general formula (1), ω, which is a subscript of N, is a number satisfying 10 ≦ ω ≦ 25 when the numerical value converted when α is 3.

In the general formula (1), when the subscripts β, γ, δ and ω are numbers outside the above ranges, the composition of the phosphor obtained by firing is an orthorhombic system represented by the general formula (1). The Sr sialon green phosphor may be different.
The Sr sialon green phosphor represented by the general formula (1) usually takes the form of a single crystal powder.

The Sr sialon green phosphor powder has an average particle size of preferably 1 μm to 100 μm, more preferably 5 μm to 20 μm, and even more preferably 10 μm to 20 μm. Here, the average particle diameter is a value measured by the Coulter counter method, it means the median D ₅₀ of the cumulative volume distribution.

When the average particle size of the Sr sialon green phosphor powder is less than 1 μm or more than 100 μm, the Sr sialon green phosphor powder or other color phosphor powders are dispersed in the cured transparent resin, and the semiconductor light emission When a light-emitting device having a structure in which green light or other color light is emitted by irradiation of ultraviolet light to blue light from the element, the light extraction efficiency from the light-emitting device may be reduced.
The Sr sialon green phosphor represented by the general formula (1) is excited when it receives ultraviolet light to blue light and emits green light.

  Here, the ultraviolet light to blue light means light having a peak wavelength in the wavelength range of ultraviolet light to blue light. The ultraviolet light to blue light is preferably light having a peak wavelength in the range of 370 nm to 470 nm.

  The Sr sialon green phosphor represented by the general formula (1) excited by receiving ultraviolet light to blue light emits green light having an emission peak wavelength in the range of 500 nm to 540 nm.

[Light emitting device]
The light emitting device is a light emitting device using the Sr sialon green phosphor represented by the general formula (1).

Specifically, the light-emitting device is formed on the substrate, the semiconductor light-emitting element that is disposed on the substrate, emits ultraviolet light to blue light, and covers the light-emitting surface of the semiconductor light-emitting element. And a light emitting unit including a phosphor that emits visible light when excited by the emitted light, and the phosphor is a light emitting device including a Sr sialon green phosphor represented by the general formula (1).
The light emitting device emits green light from the emission surface of the light emitting device if the phosphor contained in the light emitting unit is only Sr sialon green phosphor.

Further, when the light emitting device includes phosphors such as a blue phosphor and a red phosphor in addition to the Sr sialon green phosphor in the light emitting portion, the red light, the blue light and the green light emitted from the phosphors of the respective colors. A white light emitting device that emits white light from the emission surface of the light emitting device by mixing light of various colors such as light may be provided.
Furthermore, the light emitting device may include other green phosphors in addition to the Sr sialon green phosphors.

(substrate)
As the substrate, for example, ceramics such as alumina and aluminum nitride (AlN), glass epoxy resin, and the like are used. It is preferable that the substrate is an alumina plate or an aluminum nitride plate because the thermal conductivity is high and the temperature rise of the LED light source can be suppressed.

(Semiconductor light emitting device)
The semiconductor light emitting element is disposed on the substrate.
As the semiconductor light emitting element, a semiconductor light emitting element that emits ultraviolet light to blue light is used. Here, the ultraviolet light to blue light means light having a peak wavelength in the wavelength range of ultraviolet light to blue light. The ultraviolet light to blue light is preferably light having a peak wavelength in the range of 370 nm to 470 nm.

  As the semiconductor light emitting element that emits ultraviolet light to blue light, for example, an ultraviolet light emitting diode, a purple light emitting diode, a blue light emitting diode, an ultraviolet laser diode, a purple laser diode, a blue laser diode, or the like is used. When the semiconductor light emitting element is a laser diode, the peak wavelength means a peak oscillation wavelength.

(Light emitting part)
The light emitting part includes a phosphor that is excited by ultraviolet light to blue light that is emitted light from the semiconductor light emitting element and emits visible light in the transparent resin cured product, and covers the light emitting surface of the semiconductor light emitting element. Formed as follows.
The phosphor used in the light emitting unit includes at least the above Sr sialon green phosphor.

Moreover, the phosphor used in the light emitting unit may include a Sr sialon green phosphor and a phosphor other than the Sr sialon green phosphor. As a phosphor other than the Sr sialon green phosphor, for example, a red phosphor, a blue phosphor, a green phosphor, a yellow phosphor, a purple phosphor, an orange phosphor, or the like can be used. As the phosphor, a powdery one is usually used.
In the light emitting part, the phosphor is contained in the cured transparent resin. Usually, the phosphor is dispersed in a cured transparent resin.

  The transparent resin cured product used for the light emitting part is obtained by curing a transparent resin, that is, a highly transparent resin. As the transparent resin, for example, a silicone resin or an epoxy resin is used. Silicone resins are preferred because they have higher UV resistance than epoxy resins. Among silicone resins, dimethyl silicone resin is more preferable because of its high UV resistance.

  It is preferable that the light emission part is comprised in the ratio of 20-1000 mass parts of transparent resin hardened | cured materials with respect to 100 mass parts of fluorescent substance. When the ratio of the transparent resin cured product to the phosphor is within this range, the light emission intensity of the light emitting part is high.

  The film thickness of the light emitting part is usually 80 μm or more and 800 μm or less, preferably 150 μm or more and 600 μm or less. When the film thickness of the light emitting portion is not less than 80 μm and not more than 800 μm, practical brightness can be ensured with a small amount of leakage of ultraviolet light to blue light emitted from the semiconductor light emitting element. When the film thickness of the light emitting part is 150 μm or more and 600 μm or less, light emitted from the light emitting part can be brightened.

  For example, the light emitting unit first mixes a transparent resin and a phosphor to prepare a phosphor slurry in which the phosphor is dispersed in the transparent resin, and then applies the phosphor slurry to the semiconductor light emitting device and the inner surface of the globe. It is obtained by curing.

When the phosphor slurry is applied to the semiconductor light emitting element, the light emitting portion is in contact with and covered with the semiconductor light emitting element. Further, when the phosphor slurry is applied to the inner surface of the globe, the light emitting portion is formed on the inner surface of the globe while being separated from the semiconductor light emitting element. A light emitting device in which the light emitting portion is formed on the inner surface of the globe is referred to as a remote phosphor type LED light emitting device.
The phosphor slurry can be cured, for example, by heating to 100 ° C to 160 ° C.

FIG. 1 is an example of an emission spectrum of the light emitting device.
Specifically, a violet LED that emits violet light having a peak wavelength of 400 nm is used as a semiconductor light emitting element, and Sr sialon represented by Sr _2.7 Eu _0.3 Si ₁₃ Al ₃ O ₂ N ₂₁ as a phosphor. It is an emission spectrum of a green light emitting device at 25 ° C. using only a green phosphor.
The purple LED has a forward voltage drop Vf of 3.195 V and a forward current If of 20 mA.

  As shown in FIG. 1, the green light emitting device using the Sr sialon green phosphor represented by the general formula (1) as the phosphor has a high emission intensity even when excitation light having a short wavelength such as violet light is used. .

  Examples are shown below, but the present invention is not construed as being limited thereto.

[Example 1]
(Production of phosphor)
First, 419.15 g of SrCO ₃ , 432.47 g of Si ₃ N ₄ , 65.81 g of Eu ₂ O ₃ , and 0.2 g of SiC were weighed, and an appropriate amount of a fluxing agent was added thereto, followed by dry mixing. A raw material mixture was prepared. Thereafter, this first raw material mixture was filled in a boron nitride crucible.

<First firing step>
After the boron nitride crucible filled with the first raw material mixture is placed in the electric furnace, hydrogen H ₂ and nitrogen N ₂ are continuously supplied into the electric furnace at a rate of 1 L / min, respectively. Exhausted. As a result, a hydrogen-containing gas of 0.1 MPa (approximately 1 atm) containing hydrogen H ₂ and nitrogen N ₂ at a molar ratio of 1: 1 circulated in the electric furnace.
In this state, the inside of the electric furnace was heated, and the mixture in the crucible was baked at 1000 ° C. for 4 hours, whereby a lump of the first baked product was obtained in the crucible.
After removing the lump of the first fired product from the crucible and crushing, add 98.51 g of Si ₃ N ₄ , 97.06 g of Al ₂ O _3, and 372.15 g of AlN to this crushed product, and dry-mix. Thus, a second raw material mixture was prepared. Thereafter, the second raw material mixture was filled in a boron nitride crucible.

<Second firing step>
When the boron nitride crucible filled with the second raw material mixture was baked in an electric furnace at 2000 ° C. for 20 hours in a nitrogen atmosphere of 0.76 MPa (approximately 7.6 atm), a lump of baked powder was found in the crucible. Obtained.
After crushing this lump, pure water of 10 times the mass of the calcined powder was added to the calcined powder, stirred for 10 minutes, and filtered to obtain a calcined powder. This baked powder washing operation was further repeated twice to wash a total of three times. The baked powder after washing was filtered and dried, and then sieved with a nylon mesh having an opening of 75 microns to obtain a baked powder.
Table 1 shows the processing conditions of the first firing step and the second firing step.
When the calcined powder was analyzed, it was a single crystal Sr sialon green light emitting phosphor having the composition shown in Table 2.

(Phosphor analysis)
The obtained Sr sialon green light emitting phosphor was examined for average particle diameter, emission peak wavelength and luminance.
The average particle diameter is a value measured by the Coulter counter method, the value of the median D ₅₀ of the cumulative volume distribution.
The luminance was measured at room temperature (25 ° C.). The luminance at room temperature is shown as a relative value (%) (hereinafter referred to as relative luminance) with the luminance at room temperature of Example 3 described later as 100. The brightness of Example 1 was 80%.
In the examples and comparative examples shown below, the luminance at room temperature is shown as a relative value (%) (relative luminance) where the luminance at room temperature in Example 3 is 100.
Further, the yield of the Sr sialon green light-emitting phosphor represented by the general formula (1) in the fired powder was calculated from the mass of the raw material in the first raw material mixture and the second raw material mixture and the composition and mass of the fired powder. .
The measurement results are shown in Table 2.

[Examples 2-8, Comparative Examples 1-3]
A fired powder was obtained in the same manner as in Example 1 except that the firing conditions in the first firing process and the second firing process were changed as shown in Table 1.
About the obtained baked powder, it carried out similarly to Example 1, and investigated the composition, the average particle diameter, the light emission peak wavelength, the brightness | luminance, and the yield.
In Comparative Examples 1 to 3, the Sr sialon green light emitting phosphor represented by the general formula (1) was not obtained.
The measurement results are shown in Table 2.

(Evaluation about the result of Examples 1-8 and Comparative Examples 1-3)
From the results shown in Tables 1 and 2, in the examples in which the firing conditions of the first firing step and the second firing step correspond to specific conditions, the yield of the Sr sialon green light emitting phosphor represented by the general formula (1) is high. However, it was found that the yield of the Sr sialon green light emitting phosphor represented by the general formula (1) is low in the comparative example not corresponding to the specific condition.

[Examples 9 to 19, Comparative Example 4]
SrCO ₃ , Si ₃ N ₄ , Eu ₂ O ₃ and SiC in the first raw material mixture, and Si ₃ N ₄ in the second raw material mixture so that the fired powder obtained after the second firing step has the composition shown in Table 3. In addition to adjusting the blending amounts of Al ₂ O ₃ and AlN, the firing temperature in the first firing step was 1600 ° C., the firing temperature in the second firing step was 1850 ° C., and the firing time was 10 hours. In the same manner as in Example 1, a fired powder was obtained.
About the obtained baked powder, it carried out similarly to Example 1, and investigated the composition, the average particle diameter, the light emission peak wavelength, and the brightness | luminance.
Table 3 shows the measurement results.

(Evaluation of the results of Examples 9 to 19 and Comparative Example 4)
From the results shown in Table 3, it was found that when the calcined powder is an orthorhombic Sr sialon phosphor represented by the general formula (1), a green light-emitting phosphor having high luminous efficiency is obtained.

  In addition, although several embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  According to the embodiment described above, a phosphor manufacturing method, a phosphor, and a light emitting device capable of producing a europium activated sialon structure phosphor having a predetermined composition and structure using strontium carbonate as a strontium compound can be obtained. .

Claims (8)

A first firing step in which a first raw material mixture containing strontium carbonate, silicon nitride, and europium oxide is fired at 1000 ° C. to 1800 ° C. in an H ₂ -containing gas atmosphere to obtain a first fired product;
And a second firing step of obtaining a phosphor by firing the second raw material mixture containing the pulverized product of the first fired product in an N ₂ -containing gas atmosphere at 1400 ° C. to 2200 ° C. Manufacturing method. The method for producing a phosphor according to claim 1, wherein the second raw material mixture is a mixture containing a pulverized product of the first fired product and an aluminum compound. The method for producing a phosphor according to claim 2, wherein the aluminum compound is made of at least one selected from aluminum oxide and aluminum nitride. A phosphor obtained by the production method according to claim 1,
The following general formula (1)
[Chemical 1]
General formula: (Sr _1-x , Eu _x ) _α Si _β Al _γ O _δ N _ω (1)
(Wherein x is 0 <x <1, α is 0 <α ≦ 4, and β, γ, δ and ω are values converted when α is 3, 9 <β ≦ 15, 1 ≦ γ ≦ 5, 0.5 ≦ δ ≦ 3, 10 ≦ ω ≦ 25)
A phosphor which is made of europium activated sialon crystal represented by the formula (1) and emits green light when excited by ultraviolet light to blue light. 5. The phosphor according to claim 4, wherein the average particle diameter is 1 μm or more and 100 μm or less. The green light having an emission peak wavelength of 500 nm to 540 nm is emitted by being excited by ultraviolet light to blue light having a peak wavelength in a range of 370 nm to 470 nm. Phosphor. A substrate,
A semiconductor light emitting element disposed on the substrate and emitting ultraviolet light to blue light;
A light-emitting unit that is formed so as to cover the light-emitting surface of the semiconductor light-emitting element and includes a phosphor that emits visible light when excited by light emitted from the semiconductor light-emitting element;
The said fluorescent substance contains the fluorescent substance of any one of Claims 4-6, The light-emitting device characterized by the above-mentioned. The light emitting device according to claim 7, wherein the semiconductor light emitting element is a light emitting diode or a laser diode that emits light having a peak wavelength in a range of 370 nm to 470 nm.

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