JP6070536B2 - Method for producing silicate phosphor particles - Google Patents

Description

The present invention relates to a manufacturing how silicate phosphor particles that emit yellow-green to green by solid phase method. Specifically, for producing how alkaline earth metal silicate phosphor particles having a high emission characteristics.

As oxide phosphors well known as phosphor materials for white LEDs, for example, composition formula (Sr, Eu) ₃ SiO ₅ , (Sr, Ba, Eu) ₃ SiO ₅ , (Sr, Ba, Eu) _{2 There} is an alkaline earth metal silicate phosphor represented by SiO ₄ : Eu or the like. These are phosphors that are used as phosphors for high-intensity white LEDs, which emit yellow light by absorbing part of the excitation light from the blue LED, and further mix with the blue excitation light to produce white light. Have gained. In particular, (Sr, Ba, Eu) ₂ SiO ₄ : Eu used in the phosphor for high color rendering type white LED emits yellowish green to green light to enhance the color rendering.

In Patent Document 1 and Patent Document 2, calcium (Ca) is added to (Sr, Ba, Eu) ₂ SiO ₄ , and (Sr _1-a3-b3-x Ba _a3 Ca _b3 Eu _x ) ₂ SiO ₄ ( Here, a3, b3, and x are numerical values satisfying 0 ≦ a3 ≦ 1, 0 ≦ b3 ≦ 1, and 0 <x <1, respectively. It is said that this silicate phosphor can change the peak wavelength of light emission within the range of 505 nm to 598 nm by changing the composition of Ba—Sr—Ca. Furthermore, it is also known that the phosphor exhibits relatively high-efficiency light emission when irradiated with light in the range of 170 nm to 350 nm.

In the method for producing a silicate phosphor described in Patent Document 1 and Patent Document 2, strontium carbonate (SrCO ₃ ), barium carbonate (BaCO ₃ ), europium oxide (Eu ₂ O ₃ ), and silicon dioxide are used as constituent element materials. In addition to (SiO ₂ ), each powder of calcium carbonate (CaCO ₃ ) is mixed and dried by a wet mixing method as necessary. Thereafter, the mixed dried powder is calcined in the air, and a predetermined amount of flux such as calcium chloride (CaCl ₂ ) or ammonium chloride (NH ₄ Cl ₂ ) is added to the obtained calcined powder and dry mixed. The main firing is performed in an H ₂ atmosphere. And particle | grains are taken out through washing | cleaning from the obtained baked product.

According to this method, it is possible to produce a cheap and easily _{(Sr 1-a3-b3-} x Ba a3 Ca b3 Eu x) 2 SiO 4. Moreover, according to this method, it is said that high-intensity particles having an average particle diameter of 10 μm to 20 μm can be obtained. _{However, (Sr 1-a3-b3} -x Ba a3 Ca b3 Eu x) 2 SiO 4 has less sintering shrinkage, the appearance color has a strong yellow tint and has high emission characteristics Is hard to say.

Usually, when a flux is added to an oxide particle that is a silicate phosphor and fired, the oxide particle is dissolved in the flux due to the flux effect. As a result, it is said that particles having improved phosphor characteristics can be obtained by growing grains by diffusion of constituent elements through the liquid phase and promoting Eu ²⁺ doping.

_{However, (Sr 1-a3-b3} -x Ba a3 Ca b3 Eu x) a 2 SiO a _fourth raw material oxide or mixtures obtained carbonate mixed presintered and main firing, the so-called solid phase method However, in the method for producing a silicate phosphor, there is a problem that a flux effect cannot be surely exhibited, and a silicate phosphor having high light emission characteristics cannot be stably obtained.

JP 2003-110150 A JP 2004-115633 A

Therefore, the present inventors have made extensive studies to solve the above problems. As a result, silicate phosphor particles that emit yellow-green to green light are produced by a solid phase method using a raw material composed of oxides and carbonates containing constituent elements of (Sr, Ba, Eu) ₂ SiO _4. When producing phosphor particles, by optimizing the flux addition conditions and pre-baking conditions, the flux effect is sufficiently exhibited and silicate phosphor particles having high emission characteristics can be stably obtained. As a result, the present invention has been completed.

Accordingly, an object of the present invention is to provide a manufacturing how silicate phosphor particles that emit yellow-green to green which can be produced by stably solid phase method silicate phosphor particles having a high light emitting property It is in.

In order to achieve the above-mentioned object, the method for producing silicate phosphor particles of the present invention is a silicate phosphor that fires raw material powder and flux to obtain silicate phosphor particles that emit yellow-green to green light by a solid phase method. A method for producing particles, in which raw material powders of strontium carbonate, barium carbonate, europium oxide, silicon dioxide and / or calcium carbonate are weighed, mixed with each raw material powder, and then pre-fired to obtain a pre-fired powder (A) After pulverizing the first calcined powder (A) obtained in the first step and the first step, any one or more selected from the group consisting of barium carbonate, strontium carbonate, barium oxide and strontium oxide The flux is added and mixed so as to be 2% by mass to 10% by mass with respect to the temporarily calcined powder (A) obtained in the first step. Any one selected from the group consisting of barium chloride, strontium chloride, barium oxide and strontium oxide after crushing the second step of obtaining the formed powder (B) and the calcined powder (B) obtained in the second step One or more kinds of fluxes are added so that the total amount of the flux added in the second step is 10% by mass to 30% by mass with respect to the calcined powder (A) obtained in the first step. make this firing the mixture, have a third step of obtaining a calcined product, different flux used at the second step and the third step, and a flux used in the third step is at least barium chloride or strontium chloride It is characterized by including .

  According to the present invention, it is possible to stably produce alkaline earth metal silicate phosphor particles that emit yellow-green to green light and have high emission characteristics with an internal quantum efficiency of 70% or more.

Hereinafter, the method for producing silicate phosphor particles and the silicate phosphor particles according to the embodiment of the present invention will be described in detail along the following items. The method for producing silicate phosphor particles and the silicate phosphor particles according to the present invention are not limited to the following embodiments, and various modifications can be made without departing from the scope of the present invention. It is.
1. 1. Silicate phosphor particles 2. Manufacturing method of silicate phosphor particle 2-1. First step: first calcination 2-2. Second step: Second preliminary firing 2-3. Third step: main firing 2-4. Step 4: Washing and drying Evaluation of silicate phosphor particles

<1. Silicate phosphor particles>
First, the silicate phosphor particles obtained by the manufacturing method according to the present embodiment will be described.

  Silicate phosphor particles are alkaline earth metal silicate phosphor particles that can be suitably used for white LEDs, and emit light from yellowish green to green. Silicate phosphor particles contain constituent elements of strontium (Sr), barium (Ba) and europium (Eu) in addition to silicon (Si) and oxygen (O). Further, the silicate phosphor particles can contain calcium (Ca) as necessary. The average particle diameter (D50) of the silicate phosphor particles is 15 μm to 30 μm. By setting the average particle diameter (D50) of the silicate phosphor particles within this range, silicate phosphor particles having excellent light emission characteristics can be obtained, as will be described in detail later. For example, SALD7000 manufactured by Shimadzu Corporation can be used as the laser diffraction wet particle size distribution measuring apparatus for measuring the average particle diameter (D50).

  Further, by setting the average particle diameter (D50) of the silicate phosphor particles to 15 μm to 30 μm, for example, in the production of a white LED, when kneaded into a resin together with a green phosphor or a yellow phosphor, the particles disperse well. And kneadability can be improved.

  Next, the composition and emission characteristics of the silicate phosphor particles will be described.

The composition formula of the silicate phosphor particles is (Sr _1-ax Ba _a Eu _x ) ₂ SiO ₄ (where a and x are 0.55 ≦ a ≦ 0.70 and 0.05 ≦ x ≦ 0. 10). That is, in the silicate phosphor particles, barium (Ba) is in the range of 55 mol% to 70 mol%, strontium (Sr) is in the range of 20 mol% to 40 mol%, and europium (Eu) is in the range of 5 mol% to 10 mol%.

For example, when the composition of each component is a compound phase represented by (Ba _0.70 , Sr _0.24 , Eu _0.06 ) ₂ SiO ₄ , silicate phosphor particles emitting green light are obtained. In this silicate phosphor particle, barium (Ba) is contained in a range of 55 mol% to 70 mol%, and strontium (Sr) is contained in a range of 20 mol% to 40 mol%, whereby light emission when excited with light in a wavelength range of 430 nm to 470 nm. The spectrum has an emission peak in the wavelength range of 510 nm to 570 nm. Moreover, the composition range of europium (Eu) which is an activator has the preferable range of 5 mol%-10 mol%. When the silicate phosphor particles are less than 5 mol%, the emission luminance is lowered. Conversely, when the amount is more than 10 mol%, sufficient emission luminance cannot be obtained by concentration quenching.

  In addition, in the silicate phosphor particles, by increasing the substitution amount of strontium (Sr) or adding calcium (Ca) to a part of barium (Ba), it becomes a light emission color with a yellowish color, The emission peak shifts to the long wavelength side of 550 nm or more. In such a silicate phosphor particle, the luminous efficiency of the silicate phosphor particle is lowered and the water resistance is also gradually lowered. Therefore, calcium (Ca) is added as necessary.

  Thus, the silicate phosphor particles contain at least the constituent elements of silicon (Si), oxygen (O), strontium (Sr), barium (Ba) and europium (Eu), and have an average particle diameter (D50) of 15 μm. By setting it within a range of ˜30 μm, light is emitted from yellowish green to green, and the internal quantum efficiency has a very high light emission characteristic of 70% or more. When the silicate phosphor particles having such characteristics are applied to a white LED phosphor, extremely excellent color rendering properties are exhibited.

<2. Method for producing silicate phosphor particles>
Next, the manufacturing method of the silicate fluorescent substance particle concerning this embodiment is demonstrated.

<2-1. First step: first temporary firing>
In the first step, as a starting material, strontium carbonate (SrCO ₃ ), barium carbonate (BaCO ₃ ), europium oxide (Eu ₂ O ₃ ), silicon dioxide (SiO ₂ ), or as necessary Accordingly, calcium carbonate (CaCO ₃ ) powder is weighed, all raw material powders are mixed and dried, and then the mixture powder is calcined at a temperature of 1000 ° C. to 1100 ° C. in an oxidizing atmosphere to obtain a calcined powder. (A) is obtained.

As starting materials, oxides and carbonates containing constituent elements of the silicate phosphor to be produced are used. That is, in the first step, each raw material powder of strontium carbonate (SrCO ₃ ), barium carbonate (BaCO ₃ ), europium oxide (Eu ₂ O ₃ ), and silicon dioxide (SiO ₂ ) has a predetermined composition formula. Weigh. The respective raw material powders having a purity of greater than all ^99.9%, those having a specific surface area of 1m ³ / g~100m 3 / g are preferred.

  In the first step, mixing is performed using each raw material powder weighed. As a mixing method of each raw material powder, either dry or wet may be used, but dry mixing is preferable in view of the problem of waste liquid. The dry mixing can be performed using, for example, a ball mill having a media diameter of φ10 mm, but a V blender, a rocking mixer, or the like can be used.

  In the first step, when the mixed raw material powder is calcined, it is calcined in the atmosphere at a temperature range of 1000 ° C. to 1100 ° C. for 1 to 3 hours using a heating device such as an electric furnace. (A) is obtained. The temporary firing is preferably performed in an oxidizing atmosphere into which oxygen or air is introduced in order to prevent oxygen deficiency. For example, in the first step, temporary firing can be performed in the atmosphere.

<2-2. Second step: Second temporary firing>
In the second step, the calcined powder obtained in the first step is subjected to dry crushing, and then the group consisting of barium carbonate (BaCO ₃ ), strontium carbonate (SrCO ₃ ), barium oxide (BaO), and strontium oxide (SrO). Any one or more selected fluxes are added so as to be 2% by mass to 10% by mass with respect to the temporarily calcined powder (A) obtained in the first step. And in a 2nd process, after mixing these again, the obtained mixed powder is temporarily baked at 1000 to 1100 degreeC in an oxidizing atmosphere, and a temporary baked powder (B) is obtained.

In the second step, it is preferable that the temporarily fired powder (A) obtained in the first step is crushed with a dry ball mill and classified with a 350 μm sieve. This is to uniformly mix the calcined powder (A) and the flux described later. Next, in a 2nd process, a flux is added to the pulverized temporary baking powder (A), and temporary baking is performed. Here, one or more fluxes selected from the group consisting of barium carbonate (BaCO ₃ ), strontium carbonate (SrCO ₃ ), barium oxide (BaO), and strontium oxide (SrO) may be selected and added. it can. Of these, the most preferred is barium carbonate (BaCO ₃ ).

  The amount of flux added in the second step is 2% by mass to 10% by mass with respect to the temporarily fired powder (A) obtained in the first step. In the second step, when a flux of 5% by mass or more is added, a more reliable flux effect can be expected. In the second step, after the addition of the flux, the mixed powder is temporarily fired in a temperature range of 1000 ° C. to 1100 ° C. in an oxidizing atmosphere using a heating device such as an electric furnace for 1 hour to 3 hours. Obtain a powder. The temporary firing is preferably performed in an oxidizing atmosphere into which oxygen or air is introduced in order to prevent oxygen deficiency. For example, in the second step, temporary baking can be performed in the atmosphere.

<2-3. Third step: main firing>
In the third step, the calcined powder (B) obtained in the second step is crushed, and then barium chloride (BaCl ₂ ), strontium chloride (SrCl ₂ ), barium oxide (BaO), and strontium oxide (SrO). The total amount of any one or more fluxes selected from the group consisting of the total amount of flux added in the second step is 10% by mass to 30% with respect to the calcined powder (A) obtained in the first step. It is added and mixed so that it becomes mass%, and main firing is performed at 1050 ° C. to 1250 ° C. in a reducing atmosphere to obtain a fired product.

In the third step, it is preferable that the temporarily fired powder (B) obtained in the second step is crushed with a dry ball mill and classified with a 350 μm sieve. This is to uniformly mix the calcined powder (B) and the flux described later. Next, in a 3rd process, a flux is added to the pulverized temporary baking powder (B), these are put into a carbon container etc., and main baking is performed. Here, one or more kinds of fluxes selected from the group consisting of barium chloride (BaCl ₂ ), strontium chloride (SrCl ₂ ), barium oxide (BaO), and strontium oxide (SrO) may be selected and added. it can.

Of these, it is particularly preferable to use chlorides such as barium chloride (BaCl ₂ ) and strontium chloride (SrCl ₂ ). The reason is that the melting point of barium chloride (BaCl ₂ ) is 960 ° C., and the melting point of strontium chloride (SrCl ₂ ) is 870 ° C. This is because the liquid phase of the flux is surely formed, which is suitable for wetting the surface of the temporarily fired powder (B) and facilitating melting of the temporarily fired powder (B). Further, since the chloride of the flux is excellent in hot water solubility, there is also an advantage that the flux can be easily removed from the fired product using hot water in the fourth step described later.

The amount of flux added in the third step is the total amount added to the total amount of flux added in the second step, and is 10% by mass to 30% by mass with respect to the calcined powder (A) obtained in the first step. If it is less than 10% by mass, the flux effect is not sufficient, and if it is added in excess of 30% by mass, the emission characteristics are deteriorated due to excessive flux remaining such as a decrease in grain growth and contamination of the particle surface, which is not preferable. For example, in the third step, 5% by mass of barium carbonate (BaCO ₃ ) is added in the second step and pre-baked, and in the third step, 10% by mass of barium chloride (BaCl ₂ ) is added. The total amount of flux added in the third step can be 15% by mass.

A suitable addition amount of chloride flux such as barium chloride (BaCl ₂ ) or strontium chloride (SrCl ₂ ) in the third step is 10% by mass to 20% by mass, and barium oxide (BaO) or strontium oxide (SrO). A suitable addition amount of the oxide flux is 2 mass% to 5 mass%. In any of the third steps, it is preferable to add in excess of the above-mentioned range because problems such as reduction of grain growth and residual residual flux on the surface of the particle may occur, resulting in a decrease in the light emission characteristics of the silicate phosphor particles. Absent.

The firing temperature in the third step is 1050 ° C. to 1250 ° C., preferably 1150 to 1200 ° C. Using a heating device such as an electric furnace and maintaining the temperature for 1 hour to 5 hours, the highest light emission characteristics are obtained. It is easy to obtain silicate phosphor particles. In the third step, if the firing temperature is too high, the reaction between the temporarily fired powder and the flux and the carbon container and the volatilization of the flux from the surface of the temporarily fired powder particles are not preferable. Further, in the firing in the third step, for example, if the H ₂ concentration is performed in a reducing atmosphere of 1% or more, preferably 3% or more, the reduction doping of europium (Eu), which is the activation component, proceeds efficiently. For safety reasons, the upper limit is preferably 4%.

  In the third step, when the temporarily fired powder (B) obtained in the second step and the flux are mixed and fired in a reducing atmosphere, grain growth can be promoted by the presence of the flux. In general, it is known that phosphor particles obtained by firing in a reducing atmosphere in the presence of a flux are particles having a high degree of circularity close to monodispersion having an average particle diameter (D50) of several tens of μm. Yes. By using such particles, for example, in the production of a white LED, when kneaded into a resin together with a green phosphor or a yellow phosphor, the particles can be dispersed well and the kneading property can be improved. That is, in the third step, the average particle diameter (D50) of the obtained silicate phosphor particles is 15 μm to 30 μm by promoting grain growth. The average particle diameter (D50) of the silicate phosphor particles can be adjusted by the temperature of the main firing in addition to the type of flux and the amount added.

<2-4. Fourth step: washing and drying>
In the fourth step, the fired product obtained in the third step is cooled and then crushed, and the residue is removed by stirring in warm water to obtain silicate phosphor particles.

  The fired product obtained in the third step may be a solid material that has been sintered and contracted due to melting of the flux. Therefore, in the fourth step, when the fired product is a solid, the fired product is roughly crushed to about 350 μm with a stamp mill or the like in order to make the massive fired product into particles. On the other hand, when the fired body is a powder, it is not necessary to roughly crush the fired body.

  Thereafter, crushed powder and 60 ° C. warm water are added to the pot, and wet pulverization is performed for 3 minutes by a wet ball mill. In the fired product obtained in the third step, flux remains in the silicate phosphor particles and their grain boundaries. In a 4th process, a flux melt | dissolves by using warm water, and it takes out in the form where only a silicate fluorescent substance particle remains. After the lysate (flux) and the silicate phosphor particles are solid-liquid separated, the silicate phosphor particles are obtained by washing with alcohol and drying.

  As described above, in the method for producing silicate phosphor particles of the present invention, the pre-baking is performed in two steps, the type and amount of the flux added at the time of each pre-baking are specified, and the flux is added for the second time. By dividing into pre-baking and main baking, light is emitted from yellowish green to green, the average particle size (D50) is in the range of 15 μm to 30 μm, and the internal quantum efficiency is 70% or more, which has very high light emission characteristics. Alkaline earth metal silicate phosphor particles can be produced. Then, by applying the silicate phosphor particles having such excellent light emission characteristics to the white LED phosphor, a white LED phosphor exhibiting extremely excellent color rendering can be provided.

<3. Evaluation of silicate phosphor particles>
The silicate phosphor particles have an excitation spectrum (450 nm) measured by a spectrofluorometer (FP6500 manufactured by JASCO Corporation), and the absorption rate (abs), external quantum efficiency (EQE), internal quantum efficiency ( By calculating IQE) and emission peak length (Em), the emission characteristics can be evaluated. The silicate phosphor particles can be measured for particle size distribution with a dry particle size distribution meter (VD400 nano manufactured by JASCO Corporation) to determine the average particle size (D50).

  Hereinafter, although this invention is demonstrated using each Example and each comparative example, this invention is not limited to these.

Example 1
"First step"
In the first step in Example 1, 201.0 g of strontium carbonate (SrCO ₃ : SW-K manufactured by Sakai Chemical), 791.8 g of barium carbonate (BaCO ₃ : LSR manufactured by Nippon Chemical), europium oxide (Eu ₂ O ₃₎ : 72.7 g of high-purity chemical) and 174.1 g of silicon dioxide (SiO ₂ : NSS3N manufactured by Tokuyama) were placed in a SUS pot and mixed for 10 minutes. In the first step, the obtained mixed powder was dried at 80 ° C., then air was introduced at 1000 ° C. for 1 hour at 5 L / min, and preliminary firing was performed in an electric furnace.

"Second step"
In the second step in Example 1, 100 g of the temporarily fired powder (A) obtained in the first step was taken out, crushed with a dry ball mill for 10 minutes, and then classified with a 350 μm sieve. In the second step, 5% by mass of barium carbonate (BaCO ₃ ) as a flux was added to the classified powder thus obtained and mixed again. In the second step, the mixed powder thus obtained was preliminarily baked in an electric furnace after introducing air at 1000 ° C. for 1 hour at 5 L / min.

"Third step"
In the third step in Example 1, the calcined powder (B) obtained in the second step was crushed again in a dry ball mill for 10 minutes, and then 10% by mass of barium chloride (BaCl ₂ ) was added. These powders were put in a container and fired in an electric furnace in an Ar-3% H ₂ atmosphere at 1200 ° C. for 1 hour.

"4th process"
In the fourth step in Example 1, the fired product obtained in the third step was roughly crushed with a stamp mill and classified with a 350 μm sieve. In the fourth step, the classified powder thus obtained was put in a pot, hot water at 60 ° C. was added, and pulverized for 3 minutes by a wet ball mill. The solution and the particles are separated into solid and liquid, then washed with alcohol and dried at 80 ° C. to obtain alkaline earth metal silicate phosphor particles having the composition formula (Sr _0.24 Ba _0.69 Eu _0.07 ) ₂ SiO _4. Obtained.

(Example 2)
In Example 2, in the raw material composition of Example 1, the flux added in the “second step” is “barium carbonate (BaCO ₃ ) 5 mass%”, “barium carbonate (BaCO ₃ ) 5 mass%, and strontium carbonate. (SrCO ₃ ) 2% by mass ”and the flux added in the“ third step ”is changed from“ barium chloride (BaCl ₂ ) 10% by mass ”to“ barium chloride (BaCl ₂ ) 13% by mass ”. Alkaline earth metal silicate phosphor particles having the composition formula (Sr _0.24 Ba _0.69 Eu _0.07 ) ₂ SiO ₄ were obtained in the same manner as in Example 1 except for the change.

(Example 3)
In Example 3, the flux added in the “third step” in the raw material composition of Example 1 was changed from “Barium chloride (BaCl ₂ ) 10% by mass” to “Barium chloride (BaCl ₂ ) 10% by mass and strontium chloride. Alkaline earth metal silicate phosphor particles of composition formula (Sr _0.24 Ba _0.69 Eu _0.07 ) ₂ SiO _{4 in} the same manner as in Example 1 except that “(SrCl ₂ ) 5% by mass” was changed. Got.

Example 4
In Example 4, with the raw material composition of Example 1, the flux added in the “third step” was changed from “barium chloride (BaCl ₂ ) 10 mass%” to “strontium chloride (SrCl ₂ ) 10 mass%”. Except that, alkaline earth metal silicate phosphor particles having the composition formula (Sr _0.24 Ba _0.69 Eu _0.07 ) ₂ SiO ₄ were obtained in the same manner as in Example 1.

(Example 5)
In Example 5, the flux added in the “second step” in the raw material composition of Example 1 was changed from “barium carbonate (BaCO ₃ ) 5 mass%” to “barium oxide (BaO) 5 mass%”. Except that, alkaline earth metal silicate phosphor particles having the composition formula (Sr _0.24 Ba _0.69 Eu _0.07 ) ₂ SiO ₄ were obtained in the same manner as in Example 1.

(Example 6)
In Example 6, in the material composition in Example 1, the flux is added at the "third step", oxidized from "barium chloride (BaCl ₂₎ and 10 wt%""Barium chloride (BaCl ₂₎ and 10 wt% Alkaline earth metal silicate phosphor particles having the composition formula (Sr _0.24 Ba _0.69 Eu _0.07 ) ₂ SiO ₄ except that the content was changed to “2% by mass of barium (BaO)”. Got.

(Example 7)
In Example 7, the composition formula is the same as in Example 1 except that the main firing temperature was changed from “1200 ° C.” to “1100 ° C.” in the “third step” in the raw material composition of Example 1. (Sr _0.24 Ba _0.69 Eu _0.07 ) ₂ SiO ₄ alkaline earth metal silicate phosphor particles were obtained.

(Example 8)
In Example 8, in the raw material composition of Example 1, the same as in Example 1, except that the main firing temperature was changed from “1200 ° C.” to “1050 ° C.” in “third step”. (Sr _0.24 Ba _0.69 Eu _0.07 ) ₂ SiO ₄ alkaline earth metal silicate phosphor particles were obtained.

(Comparative Example 1)
In Comparative Example 1, the composition formula (Sr _0.24 Ba ₀₎ was used in the same manner as in Example 1 except that the flux was not added in the “second step” and “third step” in the raw material composition of Example 1. _.69 Eu _0.07 ) ₂ SiO ₄ alkaline earth metal silicate phosphor particles were obtained.

(Comparative Example 2)
In Comparative Example 2, in the raw material composition of Example 1, no flux was added in the “second step” and “third step”, and “barium chloride (BaCl ₂ ) as a flux was added to the starting material in the first step. Except for the addition of “10 mass%”, alkaline earth metal silicate phosphor particles having the composition formula (Sr _0.24 Ba _0.69 Eu _0.07 ) ₂ SiO ₄ were obtained in the same manner as in Example 1.

(Comparative Example 3)
In Comparative Example 3, in the raw material composition of Example 5, the flux “barium oxide (BaO) 5 mass%” was not added in the “second step” and the flux added in the “third step” Except for changing from “barium (BaCl ₂ ) 10% by mass” to “barium chloride (BaCl ₂ ) 10% by mass and barium oxide (BaO) 5% by mass” and adding the flux only to the third step. In the same manner as in Example 5, alkaline earth metal silicate phosphor particles having the composition formula (Sr _0.24 Ba _0.69 Eu _0.07 ) ₂ SiO ₄ were obtained.

  As can be seen from the above results, in Examples 1 to 8, all of the obtained silicate phosphor particles stably have an internal quantum efficiency (IQE) exceeding 70%, and the emission wavelength is stable at 525 nm. As a result, it was confirmed that the phosphor was excellent in characteristics (light emission characteristics).

  On the other hand, in Comparative Examples 1 to 3, high luminescence characteristics cannot be confirmed for the obtained silicate phosphor particles, and the average particle diameter (D50) is very small, and no grain growth due to flux is observed. Was confirmed. That is, when the flux is not added and when the flux addition conditions are different from the manufacturing method of the silicate phosphor particles, the internal quantum efficiency (IQE) is not sufficiently improved, and the grain growth is also insufficient. It has been found.

  From the results of Examples 1 to 8 and Comparative Examples 1 to 3, preliminary firing was performed in two steps, the type and amount of flux added at each temporary firing was specified, and the addition of flux was further performed. By dividing into the second calcination and the main calcination, the obtained silicate phosphor particles have an average particle diameter (D50) in the range of 15 μm to 30 μm, and emit light from yellow green to green, and the internal quantum efficiency is It was confirmed that it had a very high light emission characteristic of 70% or more. Thereby, when the silicate phosphor particles having such characteristics are applied to a phosphor for white LED, extremely excellent color rendering properties are exhibited.

Claims (4)

A method for producing silicate phosphor particles by firing raw material powder and a flux and obtaining silicate phosphor particles emitting yellow-green to green light by a solid phase method,
A first step of weighing each raw material powder of strontium carbonate, barium carbonate, europium oxide, silicon dioxide and / or calcium carbonate, mixing each of the raw material powders, and performing preliminary baking to obtain a temporary baking powder (A);
After crushing the calcined powder (A) obtained in the first step, any one or more fluxes selected from the group consisting of barium carbonate, strontium carbonate, barium oxide, and strontium oxide are used as the first powder. A second step of obtaining a pre-baked powder (B) by adding and mixing the pre-fired powder (A) obtained in the step so as to be 2% by mass to 10% by mass, and pre-baking;
After crushing the calcined powder (B) obtained in the second step, any one or more fluxes selected from the group consisting of barium chloride, strontium chloride, barium oxide, and strontium oxide are added to the second powder. The total amount added with the total amount of flux added in the process is added and mixed so as to be 10% by mass to 30% by mass with respect to the temporarily calcined powder (A) obtained in the first process, and then the main calcination is performed. have a third step of obtaining a calcined product,
The method for producing silicate phosphor particles, wherein the flux used in the second step and the third step are different and the flux used in the third step contains at least barium chloride or strontium chloride .   In the first step and the second step, preliminary firing is performed at 1000 ° C. to 1100 ° C. in an oxidizing atmosphere, and in the third step, main firing is performed at 1050 ° C. to 1250 ° C. in a reducing atmosphere. The method for producing silicate phosphor particles according to claim 1.   The method for producing silicate phosphor particles according to claim 1 or 2, further comprising a fourth step of cooling and crushing the fired product obtained in the third step to remove the residue. . The flux used in the second step is any one of barium carbonate, barium oxide, or a mixture of barium carbonate and strontium carbonate, and the flux used in the third step is composed of barium chloride, strontium chloride, barium chloride and strontium chloride. The method for producing silicate phosphor particles according to any one of claims 1 to 3, which is either a mixture or a mixture of barium chloride and barium oxide.