JP5730084B2 - Europium activated strontium sialon phosphor, method for producing the same, and light emitting device - Google Patents

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 (Sr sialon phosphor) having a europium activated sialon (Si—Al—O—N) structure containing strontium is known as the phosphor.

International Publication No. 2007/105631

However, the conventional phosphor has a problem that when used in a high temperature region of about 150 ° C., the light emission efficiency is lower than when used in a normal temperature (25 ° C.) region. Hereinafter, the fact that the luminous efficiency of the phosphor does not decrease or the degree of decrease when used in a high temperature region of about 150 ° C. as compared to when used in a normal temperature region is referred to as good temperature characteristics. In addition, the fact that the luminous efficiency of the phosphor is greatly reduced when used in a high temperature region of about 150 ° C. compared to the case where it is used in a normal temperature region is referred to as poor temperature characteristics.
Moreover, it is preferable that the phosphor has high luminous efficiency at room temperature (25 ° C.).

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a phosphor having high luminous efficiency and good temperature characteristics, a method for manufacturing the same, and a light emitting device.

  When the phosphor and light-emitting device of the embodiment are manufactured under high pressure, a phosphor having a crystal structure that is thermodynamically stable and has good crystallinity is obtained, and this phosphor has improved temperature characteristics. Was found and completed.

The method for producing the europium-activated strontium sialon phosphor of the embodiment solves the above-mentioned problems, and includes a strontium compound containing at least one of strontium oxide and strontium carbonate, silicon nitride, aluminum nitride, and aluminum oxide. And a phosphor raw material mixture containing europium oxide is fired at 1400 ° C. to 2200 ° C. in an inert gas atmosphere of 50 MPa to 200 MPa.

  The phosphor of the embodiment solves the above-described problems, is obtained by the production method, and has 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, 0.5 ≦ δ ≦ 3, 1 ≦ γ ≦ 5, 10 ≦ ω ≦ 25)

It is characterized in that it emits green light when excited by ultraviolet light, violet light or blue light.

  In addition, the phosphor of the embodiment solves the above-described problems, and is obtained by the production method, and has the following general formula (2).

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

It is characterized in that it emits red light when excited by ultraviolet light, violet light or blue light.

  Furthermore, the light-emitting device of the embodiment solves the above-described problem. A substrate, a semiconductor light-emitting element that is disposed on the substrate and emits ultraviolet light, violet light, or blue light, and the semiconductor light-emitting element A phosphor that is formed so as to cover a light emitting surface and includes a phosphor that emits visible light when excited by light emitted from the semiconductor light emitting element, and the phosphor is any one of claims 2 to 7. The phosphor of the term is included.

It is an example of the emission spectrum of a light-emitting device. It is another example of the emission spectrum of a light-emitting device. It is a graph which shows the temperature characteristic of the fluorescent substance produced by the Example and the comparative example.

  The phosphor and the light emitting device of the embodiment will be described. The phosphor of the embodiment includes a green phosphor that emits green light when excited by ultraviolet light, purple light, or blue light, and a red phosphor that emits red light when excited by ultraviolet light, purple light, or blue light. There is.

[Green phosphor]
The green phosphor has the following general formula (1)

[Chemical formula 3]
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)

And a phosphor that emits green light when excited by ultraviolet light, violet light, or blue light. Hereinafter, the phosphor emitting green light is also referred to as “Sr sialon green phosphor”.

Here, the relationship between the europium activated sialon crystal having the composition represented by the general formula (1) and the Sr sialon green phosphor will be described.
The europium activated sialon crystal having the composition represented by the general formula (1) is an orthorhombic single crystal.
On the other hand, in the Sr sialon green phosphor, a crystal composed of one europium activated sialon crystal having a composition represented by the general formula (1), or two or more of these europium activated sialon crystals are aggregated. It is an aggregate of crystal bodies.

Usually, the Sr sialon green phosphor takes the form of a single crystal powder.

  When the Sr sialon green phosphor is an aggregate of crystals obtained by aggregating two or more of the europium activated sialon crystals, the Sr sialon green phosphor is separated for each europium activated sialon crystal by crushing. It is possible.

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 does not become a phosphor, and when x is 1, the luminous efficiency of the Sr sialon green phosphor is lowered.

Further, the smaller the x is in the range of 0 <x <1, the easier it is for the emission efficiency of the Sr sialon 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), the total amount of Sr and Eu is represented by α. By specifying the numerical values of β, γ, δ, and ω when the total amount α is a constant value 3, the ratio of α, β, γ, δ, and ω in the general formula (1) becomes clear. ing.

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 is usually a single crystal powder, that is, each particle constituting the powder is in a single crystal particle state.
The Sr sialon green phosphor powder has an average particle size of usually 1 μm to 100 μm, preferably 5 μm to 80 μm, more preferably 8 μm to 80 μm, and more preferably 8 μm to 40 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 with ultraviolet light, violet light, or blue light from the element, light extraction efficiency from the light-emitting device may be reduced.
The Sr sialon green phosphor represented by the general formula (1) is excited and emits green light when irradiated with ultraviolet light, violet light, or blue light.

  Here, ultraviolet light, violet light or blue light means light having a peak wavelength in the wavelength range of ultraviolet light, violet light or blue light. The ultraviolet light, violet light, or 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, violet light, or blue light emits green light having an emission peak wavelength in the range of 500 nm to 540 nm.

[Red phosphor]
The red phosphor has the following general formula (2)

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

Is a phosphor that emits red light when excited by ultraviolet light, violet light, or blue light. Hereinafter, the phosphor emitting red light is also referred to as “Sr sialon red phosphor”.

Here, the relationship between the europium activated sialon crystal having the composition represented by the general formula (2) and the Sr sialon red phosphor will be described.
The europium activated sialon crystal having the composition represented by the general formula (2) is an orthorhombic single crystal.
On the other hand, in the Sr sialon red phosphor, a crystal composed of one europium activated sialon crystal having a composition represented by the general formula (2), or two or more of these europium activated sialon crystals are aggregated. It is an aggregate of crystal bodies.

  Usually, Sr sialon red phosphor takes the form of single crystal powder.

  When the Sr sialon red phosphor is an aggregate of crystals obtained by aggregating two or more of the europium activated sialon crystals, the Sr sialon red phosphor is separated for each europium activated sialon crystal by crushing. It is possible.

In the general formula (2), 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 Sr sialon red phosphor is lowered.

Also, the smaller the x is in the range of 0 <x <1, the easier it is to reduce the luminous efficiency of the Sr sialon red phosphor. 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 (2), the total subscript (1-x) α of Sr is a number satisfying 0 <(1-x) α <3. Further, the overall subscript xα of Eu is a number satisfying 0 <xα <3. That is, in the general formula (2), the total subscripts of Sr and Eu are numbers exceeding 0 and less than 3, respectively.

  In the general formula (2), the total amount of Sr and Eu is represented by α. By specifying the numerical values of β, γ, δ, and ω when the total amount α is a constant value 2, the specification of the ratio of α, β, γ, δ, and ω in the general formula (2) becomes clear. ing.

In the general formula (2), β, γ, δ, and ω are values converted when α is 2.
In the general formula (2), β, which is a subscript of Si, is a number satisfying 5 ≦ β ≦ 9 when the numerical value converted when α is 2.
In the general formula (2), γ, which is a subscript of Al, is a number satisfying 1 ≦ γ ≦ 5 when the numerical value converted when α is 2.
In the general formula (2), δ, which is a subscript of O, is a number satisfying 0.5 ≦ δ ≦ 2 in terms of a numerical value converted when α is 2.
In the general formula (2), ω, which is a subscript of N, is a number satisfying 5 ≦ ω ≦ 15 when the numerical value converted when α is 2.

  In the general formula (2), 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 (2). The Sr sialon red phosphor may be different.

The Sr sialon red phosphor is usually a single crystal powder, that is, each particle constituting the powder is in a single crystal particle state.
The Sr sialon red phosphor powder has an average particle size of preferably 1 μm to 100 μm, more preferably 5 μm to 50 μm, and even more preferably 10 μm to 35 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 red phosphor powder is less than 1 μm or more than 100 μm, the Sr sialon red 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 red light or other color light is emitted by irradiation of ultraviolet light, violet light, or blue light from the element, light extraction efficiency from the light-emitting device may be reduced.
The Sr sialon red phosphor represented by the general formula (2) is excited when it receives ultraviolet light, violet light or blue light, and emits red light.

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

  The Sr sialon red phosphor represented by the general formula (2) excited by receiving ultraviolet light, violet light or blue light emits red light having an emission peak wavelength in the range of 550 nm to 650 nm.

[Method for producing green phosphor and red phosphor]
The method for producing the Sr sialon green phosphor represented by the general formula (1) and the Sr sialon red phosphor represented by the general formula (2) includes a strontium compound containing at least one of strontium oxide SrO and strontium carbonate SrCO ₃ . And a phosphor raw material mixture containing silicon nitride Si ₃ N ₄ , aluminum nitride AlN, aluminum oxide Al ₂ O _3, and europium oxide Eu ₂ O ₃ in an inert gas atmosphere of 50 MPa to 200 MPa. Baking is performed at a temperature of from 2 to 200 ° C.

The phosphor raw material mixture includes a strontium compound containing at least one of strontium oxide SrO and strontium carbonate SrCO ₃ , silicon nitride Si ₃ N ₄ , aluminum nitride AlN, aluminum oxide Al ₂ O _3, and europium oxide Eu ₂ O. ₃ is included.

  Of the strontium compounds, strontium oxide is preferable because it does not contain the carbon atom C, so that there is little possibility of carbon atoms being mixed as impurities in the phosphor when fired under high pressure as in the present invention.

A strontium compound containing at least one of strontium oxide SrO and strontium carbonate SrCO ₃ , silicon nitride Si ₃ N ₄ , aluminum nitride AlN, aluminum oxide Al ₂ O _3, and europium oxide Eu _{2 in the} phosphor raw material mixture. The compounding amount with O ₃ is such that the composition ratio of Sr, Si, Al, Eu, O and N in the phosphor becomes a desired one in consideration of the decrease in O from the phosphor raw material mixture during firing. Set as appropriate.

The phosphor raw material mixture may further contain, as a flux agent, an alkali metal or alkaline earth metal fluoride such as potassium fluoride which is a reaction accelerator, strontium chloride SrCl ₂ or the like.
The phosphor 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.

The phosphor 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. In the production method of the present invention, the firing atmosphere becomes a high pressure. As a firing apparatus that can withstand such high pressure, for example, an electric furnace capable of hermetic firing is used.
An inert gas is used as the firing atmosphere. As the inert gas, for example, N ₂ gas, Ar gas, a mixed gas of N ₂ and H ₂ or the like is used.

  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. Obtain body powder.

N ₂ in the firing atmosphere has a function of eliminating an appropriate amount of oxygen O from the phosphor raw material mixture when the phosphor powder is fired from the phosphor raw material mixture.

  Further, Ar in the firing atmosphere has an effect of not supplying excess oxygen O to the phosphor material mixture when the phosphor powder is fired from the phosphor material mixture.

Further, H ₂ in the firing atmosphere acts as a reducing agent when the phosphor powder is fired from the phosphor raw material mixture, and more oxygen O is lost from the phosphor raw material mixture than N ₂ .

For this reason, when H ₂ is contained in the inert gas, the firing time can be shortened compared to the case where H ₂ is not contained in the inert gas. However, if the content of H _{2 in} the inert gas is too large, the composition of the obtained phosphor powder is represented by the Sr sialon green phosphor represented by the general formula (1) or the general formula (2). Unlike the Sr sialon red phosphor, the luminous efficiency of the phosphor powder may be reduced.

Inert 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 the inert _gas, 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 inert gas is within the above range, that is, usually 10: 0 to 1: 9, a high-quality single crystal with few crystal structure defects in a short time firing The phosphor powder can be obtained.

The molar ratio of N ₂ and H ₂ in the inert gas, the N ₂ and H ₂ which is continuously fed into the chamber of the calciner, the ratio of the flow rate of N ₂ and H ₂ are in the ratio The above ratio, that is, usually 10: 0 to 1: 9, can be obtained by supplying the gas in such a manner and continuously discharging the mixed gas in the chamber.

The Sr sialon green phosphor represented by the general formula (1) contains more nitrogen N than the Sr sialon red phosphor represented by the general formula (2). For this reason, the Sr sialon green phosphor represented by the general formula (1) and the Sr sialon red phosphor represented by the general formula (2) are SrO, SrCO ₃ , and Si ₃ N in the phosphor raw material mixture. _4, AlN, _Al 2 _{O 3,} and _Eu changing the mixing ratio of each raw material such as 2 _{O 3,} may be separately formed by changing the amount of inert gas in the furnace during firing.
For example, when the inert gas in the furnace at the time of firing is nitrogen gas, the Sr sialon red phosphor represented by the general formula (2) can be obtained by reducing the pressure of the nitrogen gas to about 50 MPa (approximately 500 atm). It is easy to obtain, and when it is increased to about 200 MPa (approximately 2000 atm), the Sr sialon green phosphor represented by the general formula (1) is easily obtained.

  An inert gas that is a firing atmosphere is preferably distributed so as to form an air flow in a chamber of a firing apparatus because firing is performed uniformly.

  The pressure of the inert gas that is the firing atmosphere is usually 50 MPa (approximately 500 atm) to 200 MPa (approximately 2000 atm).

When the pressure of the inert gas that is the firing atmosphere is in the range of 50 MPa to 200 MPa, the crystal structure of the phosphor after firing takes a thermodynamically more stable phase than before, and the phosphor after firing has a Since the crystallinity of the crystal structure is improved, a phosphor having high luminous efficiency and good temperature characteristics can be obtained. Here, good crystallinity means that there are few impurities and lattice defects.
Moreover, when the pressure of the inert gas is within the range of 50 MPa to 200 MPa, crystal growth during firing may be improved. In this case, the phosphor can be fired in a short time.

  In the present invention, the effect of improving the luminous efficiency and temperature characteristics of the phosphor due to the pressure of the inert gas that is the firing atmosphere being in the range of 50 MPa to 200 MPa is usually of the composition represented by the general formula (2). The Sr sialon green phosphor having the composition represented by the general formula (1) is larger than the Sr sialon red phosphor.

  When the pressure of the firing atmosphere is less than 50 MPa, the composition of the phosphor powder obtained after firing tends to be significantly different from that of the phosphor raw material mixture charged in the crucible before firing. As a result, the obtained phosphor is easily different from the Sr sialon green phosphor represented by the general formula (1) or the Sr sialon red phosphor represented by the general formula (2). There is a possibility that the luminous efficiency is lowered and the temperature characteristics are deteriorated.

  Specifically, when the Sr sialon green phosphor having the composition represented by the general formula (1) is to be produced, if the pressure of the firing atmosphere is less than 50 MPa, the crystal structure is a thermodynamically unstable phase. Thus, it becomes difficult to fire the phosphor, the luminous efficiency of the phosphor is lowered, and the temperature characteristics of the phosphor are liable to deteriorate.

  For example, when an Sr sialon green phosphor having a composition represented by the general formula (1) is to be manufactured, if the pressure of the firing atmosphere is 0.1 MPa (approximately 1 atm), the crystal structure during firing is thermodynamic. Instable phase, making it difficult to synthesize phosphors. Further, when the Sr sialon green phosphor having the composition represented by the general formula (1) is to be manufactured, if the pressure of the firing atmosphere is 0.7 MPa (approximately 7 atm), the phosphor itself can be fired. Although it exists, the luminous efficiency of the phosphor tends to be low and the temperature characteristics are likely to deteriorate.

  Moreover, when it is going to manufacture Sr sialon red fluorescent substance of the composition represented by General formula (2), when the pressure of a baking atmosphere is less than 50 Mpa, since the crystallinity of fluorescent substance is low, light emission of fluorescent substance is carried out. It tends to be less efficient and have poor temperature characteristics.

  For example, when an Sr sialon red phosphor having the composition represented by the general formula (2) is to be manufactured, if the pressure of the firing atmosphere is 0.7 MPa (approximately 7 atm), the luminous efficiency of the phosphor is lowered. Or temperature characteristics are likely to deteriorate.

  When the pressure in the firing atmosphere exceeds 200 MPa, the firing conditions are not particularly changed even when compared with the case where the pressure is 200 MPa or less, which is not preferable because energy is wasted.

  In addition, when manufacturing Sr sialon green fluorescent substance represented by General formula (1), the pressure of the inert gas which is a baking atmosphere becomes like this. Preferably it is 100 MPa-150 MPa.

  Moreover, when manufacturing Sr sialon red fluorescent substance represented by General formula (2), the pressure of the inert gas which is a baking atmosphere becomes like this.

The firing temperature is usually 1400 ° C to 2200 ° C, preferably 1800 ° C to 2000 ° C, more preferably 1850 ° C to 1950 ° C.
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 lower than 1400 ° C., the color of the light emitted from the phosphor powder obtained by being excited by ultraviolet light, violet light or blue light may not be a desired color. That is, when it is desired to manufacture the Sr sialon green phosphor represented by the general formula (1), the color of light emitted by being excited by ultraviolet light, violet light or blue light becomes a color other than green, When it is desired to manufacture the Sr sialon red phosphor represented by (2), there is a possibility that the color of light emitted by being excited by ultraviolet light, violet light or blue light becomes a color other than red.

When the firing temperature exceeds 2200 ° C., the composition of the phosphor powder obtained by increasing the disappearance degree of N and O during firing is Sr sialon green phosphor represented by the general formula (1) or the general formula ( It is easy to be different from the Sr sialon red phosphor represented by 2), which may reduce the luminous efficiency of the phosphor powder.
The firing time is usually 0.5 hours to 20 hours, preferably 1 hour to 10 hours, more preferably 3 hours to 5 hours, and more preferably 3.5 hours to 4.5 hours.

  When the firing time is less than 0.5 hours or exceeds 20 hours, the composition of the obtained phosphor powder is represented by the Sr sialon green phosphor represented by the general formula (1) or the general formula (2). Therefore, the luminous efficiency of the phosphor powder may be reduced.

  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 general formula (1) or Sr sialon red phosphor represented by general formula (2).

[Light emitting device]
The light emitting device is a light emitting device using the Sr sialon green phosphor represented by the general formula (1) or the Sr sialon red phosphor represented by the general formula (2).
Specifically, the light-emitting device is formed on a substrate, a semiconductor light-emitting element that is disposed on the substrate, emits ultraviolet light, violet light, or blue light, and covers a light-emitting surface of the semiconductor light-emitting element. A phosphor including a phosphor that emits visible light when excited by light emitted from the light emitting element, and the phosphor is represented by the Sr sialon green phosphor represented by the general formula (1) or the general formula (2). Is a light emitting device including the Sr sialon red phosphor.

  The phosphor may contain at least one of the Sr sialon green phosphor represented by the general formula (1) and the Sr sialon red phosphor represented by the general formula (2). The Sr sialon green phosphor represented by the formula (2) and the Sr sialon red phosphor represented by the general formula (2) may be included.

  The light emitting device emits green light from the emission surface of the light emitting device if the phosphor contained in the light emitting portion is only Sr sialon green phosphor, and the phosphor contained in the light emitting portion is only Sr sialon red phosphor. If there is, red light is emitted from the emission surface of the light emitting device.

  In addition, the light emitting device may include a phosphor such as a blue phosphor and a red phosphor such as a Sr sialon red phosphor in addition to the Sr sialon green phosphor in the light emitting unit, or the Sr sialon red phosphor. In addition, if a phosphor such as a blue phosphor and a green phosphor such as Sr sialon green phosphor is included, the light of each color such as red light, blue light and green light emitted from each color phosphor A white light emitting device that emits white light from the emission surface of the light emitting device can also be obtained by color mixing.

  Further, the light emitting device may contain other green phosphors in addition to Sr sialon green phosphors, or may contain other red phosphors in addition to Sr sialon red phosphors.

  The light emitting device may include a Sr sialon green phosphor represented by the general formula (1) and a Sr sialon red phosphor represented by the general formula (2) as phosphors. When both Sr sialon green phosphor and Sr sialon red phosphor are included as phosphors, a light emitting device with good temperature characteristics can be obtained.

(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, violet light, or blue light is used. Here, ultraviolet light, violet light or blue light means light having a peak wavelength in the wavelength range of ultraviolet light, violet light or blue light. The ultraviolet light, violet light, or 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, violet light, or blue light, for example, an ultraviolet light emitting diode, a violet light emitting diode, a blue light emitting diode, an ultraviolet laser diode, a violet laser diode, and a blue laser diode are 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, violet light, or blue light, which is emitted light from the semiconductor light emitting element, and emits visible light in the transparent resin cured product, and the light emitting surface of the semiconductor light emitting element It is formed so that it may coat | cover.

  The phosphor used in the light emitting unit includes at least the above Sr sialon green phosphor or Sr sialon red phosphor. The phosphor may include both Sr sialon green phosphor and Sr sialon red phosphor.

In addition, the phosphor used in the light emitting unit may include the above Sr sialon green phosphor or Sr sialon red phosphor and a phosphor other than the Sr sialon green phosphor or Sr sialon red phosphor. . As a phosphor other than the Sr sialon green phosphor or the Sr sialon red phosphor, for example, a red phosphor, a blue phosphor, a green phosphor, a yellow phosphor, a purple phosphor, an orange phosphor and 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, violet light, or 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 3.199 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. .

FIG. 2 is another 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 device, and Sr sialon red fluorescence represented by Sr _1.6 Eu _0.4 Si ₇ Al ₃ ON ₁₃ as a phosphor. It is an emission spectrum of a red light emitting device at 25 ° C. using only the body.
The purple LED has a forward voltage drop Vf of 3.190 V and a forward current If of 20 mA.

  As shown in FIG. 2, the red light emitting device using the Sr sialon red phosphor represented by the general formula (2) 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.

(Production of green phosphor)
First, 260 g of SrO, 63 g of Al ₂ O ₃ , 63 g of AlN, 63 g of Si ₃ N ₄ , 568 g of Eu ₃ O _3, and 49 g of Eu ₂ O ₃ were weighed. Was prepared (Sample No. 1). Thereafter, the phosphor raw material mixture was filled in a boron nitride crucible. Table 1 shows the blending amount of the raw materials of the phosphor raw material mixture.
The boron nitride crucible filled with the phosphor raw material mixture was baked at 1900 ° C. for 4 hours in a 200 MPa (approximately 2000 atmospheres) nitrogen atmosphere in an electric furnace capable of hermetic firing at high pressure. A lump was 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, whereby a baked powder was obtained (Sample No. 1).
When the fired powder was analyzed, it was a single crystal Sr sialon green phosphor having the composition shown in Table 2.
The composition of the fired powder is shown in Table 2.

With respect to the obtained Sr sialon phosphor, the emission peak wavelength, emission efficiency, emission efficiency maintenance ratio at 150 ° C., and average particle diameter were measured.
Luminous efficiency is the same as the sample No. described later. 5 is shown as a relative value (%) where the luminous efficiency (lm / W) at 25 ° C. is 100.
The luminous efficiency maintenance rate at 150 ° C. is the percentage obtained by dividing the luminous efficiency at 150 ° C. by the luminous efficiency at 25 ° C. after measuring the luminous efficiency (lm / W) at 150 ° C. Is. The luminous efficiency maintenance rate at 150 ° C. is an index for evaluating the temperature characteristics.
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.
Table 3 shows the measurement results of the emission peak wavelength, the emission efficiency, and the emission efficiency maintenance ratio at 150 ° C. Table 2 shows the measurement results of the average particle diameter.

(Production of other green phosphors)
Except for changing the blending amount of the raw material of the phosphor raw material mixture as shown in Table 1, sample No. In the same manner as in Example 1, green phosphors were prepared (Sample Nos. 2 to 10).
Sample No. 1-4 are the Examples which changed the pressure of baking atmosphere within the scope of the present invention. Sample No. 5 to 8 are comparative examples in which the pressure of the firing atmosphere is outside the scope of the present invention. Furthermore, sample no. Examples 9 and 10 are examples in which the composition represented by the general formula (1) was changed.
With respect to the obtained green phosphor (sample Nos. 2 to 10), sample no. In the same manner as in Example 1, the emission peak wavelength, emission efficiency, emission efficiency maintenance rate at 150 ° C., and average particle diameter were measured.
Table 2 shows the composition of the fired powder and the measurement results of the average particle diameter. Table 3 shows the measurement results of the emission peak wavelength, the emission efficiency, and the emission efficiency maintenance ratio at 150 ° C.

(Production of red phosphor)
Except for changing the blending amount of the raw material of the phosphor raw material mixture as shown in Table 1, sample No. As in the case of No. 1, a fired powder was obtained (Sample Nos. 11 to 20).
When these fired powders were analyzed, they were single crystal Sr sialon red phosphors having the compositions shown in Table 2.
Sample No. 11-14 is the Example which changed the pressure of baking atmosphere within the scope of the present invention. Sample No. 15 to 18 are comparative examples in which the pressure of the firing atmosphere is outside the scope of the present invention. Furthermore, sample no. 19 and 20 are examples in which the composition represented by the general formula (2) was changed.
In contrast to the obtained red phosphor (sample Nos. 11 to 20), the green phosphor sample No. In the same manner as in Example 1, the emission peak wavelength, emission efficiency, emission efficiency maintenance rate at 150 ° C., and average particle diameter were measured.
Table 2 shows the composition of the fired powder and the measurement results of the average particle diameter. Table 3 shows the measurement results of the emission peak wavelength, the emission efficiency, and the emission efficiency maintenance ratio at 150 ° C.

  It can be seen from Tables 1 to 3 that the phosphors fired under a high pressure within a specific range have a high light emission rate and temperature characteristics (light emission efficiency maintenance rate at 150 ° C.).

FIG. 3 is a graph showing the temperature characteristics of the phosphors produced in the examples and comparative examples.
Specifically, Sample No. 2 (Example) and No. 2 5 (Comparative Example) Sr sialon green phosphors represented by Sr _2.7 Eu _0.3 Si ₁₃ Al ₃ O ₂ N ₂₁ are arranged in the air each capable of temperature control, and for this phosphor, The emission intensity in the case of irradiating light of a monochromatic light source that emits violet light having a peak wavelength of 450 nm is measured for each temperature of the atmosphere.

  From FIG. 3, sample No. baked under a high pressure of 100 MPa (approximately 1000 atm). 2 is a sample No. 2 fired under a low pressure of 0.7 MPa (approximately 7 atm). It can be seen that the emission intensity is high even at high temperatures and the temperature characteristics are good as compared with the phosphor No. 5.

  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 and a light emitting device having high luminous efficiency and good temperature characteristics can be obtained.

Claims (9)

A phosphor raw material mixture containing a strontium compound containing at least one of strontium oxide and strontium carbonate, silicon nitride, aluminum nitride, aluminum oxide, and europium oxide is obtained in an inert gas atmosphere of 50 to 200 MPa in an amount of 1400. A method for producing a europium-activated strontium sialon phosphor, characterized by firing at a temperature of 2 ° C to 2200 ° C. 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, 0.5 ≦ δ ≦ 3, 1 ≦ γ ≦ 5, 10 ≦ ω ≦ 25)
Consisting of europium activated sialon crystals represented by
A europium-activated strontium sialon phosphor that emits green light when excited by ultraviolet light, purple light, or blue light. Obtained by the production method according to claim 1, the following general formula (2)
[Chemical 2]
General formula: (Sr _1-x , Eu _x ) _α Si _β Al _γ O _δ N _ω (2)
(Wherein x is 0 <x <1, α is 0 <α ≦ 3, and β, γ, δ, and ω are values converted when α is 2, 5 ≦ β ≦ 9, 0.5 ≦ δ ≦ 2, 1 ≦ γ ≦ 5, 5 ≦ ω ≦ 15)
Consisting of europium activated sialon crystals represented by
A europium-activated strontium sialon phosphor that emits red light when excited by ultraviolet light, purple light, or blue light. The europium-activated strontium sialon phosphor according to claim 2 or 3, wherein the ultraviolet light, violet light, or blue light is light having a peak wavelength in a range of 370 nm to 470 nm. The europium-activated strontium sialon phosphor according to any one of claims 2 to 4, wherein the average particle size is 1 µm or more and 100 µm or less. 6. The europium-activated strontium sialon phosphor emitting green light according to claim 2, wherein an emission peak wavelength is 500 nm or more and 540 nm or less. The europium activated strontium sialon phosphor emitting yellow to red light according to any one of claims 3 to 5, wherein the emission peak wavelength is 550 nm or more and 650 nm or less. A substrate,
A semiconductor light emitting device disposed on the substrate and emitting ultraviolet light, violet light or blue light;
A light-emitting unit that includes a phosphor that is formed so as to cover the light-emitting surface of the semiconductor light-emitting element and that emits visible light when excited by light emitted from the semiconductor light-emitting element,
The said fluorescent substance contains the europium activated strontium sialon fluorescent substance of any one of Claims 2-7, The light-emitting device characterized by the above-mentioned. 9. The light emitting device according to claim 8, 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.

Images