KR20120093368A - Process for production of eu-activated alkaline earth metal silicate phosphor - Google Patents

Abstract

The present invention provides a precursor having high uniformity in chemical composition in the production of Eu-activated alkaline earth metal silicate phosphors in which the ratio of all metal component elements (Sr, Ba, Eu, Si) and Si is 4: 1 or 3: 1. It is an object of the present invention to provide a method for producing a single-phase, high brightness Eu activated alkaline earth metal silicate phosphor having a uniform chemical composition by allowing synthesis at a lower temperature than that of the conventional method and by heat-treating the precursor.
In the method for producing an Eu-activated alkaline earth metal silicate phosphor, as Step 1, strontium, barium, europium, and silicon, which are constituent metal components, are used as aqueous solutions, and after the aqueous solutions are mixed, the solution is maintained at a liquid temperature of 30 占 폚 to 100 占 폚. And forming a transparent gel in a state in which the entire amount of the entire metal component is uniformly dispersed.

Description

PROCESS FOR PRODUCTION OF EU-ACTIVATED ALKALINE EARTH METAL SILICATE PHOSPHOR

The present invention [formula, Eu ^{2 +} a strontium silicate-based phosphor activated to represent the yellow light emission of high luminance by a light excitation in the ultraviolet to visible region _{(Sr 1 -y, Eu y)} 3 SiO 5 ( stage, 0 <Y < 0.1)], and composition formula (Ba _x , Sr _{1 -xy} , Eu _y ) ₃ SiO ₅ (where 0 <X < _1,0 ), which exhibits light emission of high luminance from green to yellow by light excitation in the ultraviolet to visible region. <Y <0.1), alkaline earth metal silicate-based fluorescent substance which activated Eu ²⁺ of composition formula (Ba _x , Sr _1-xy , Eu _y ) ₂ SiO ₄ (where 0 <X <1, 0 <Y <0.1) It relates to a method for producing.

White LEDs generate white light by mixing LEDs emitting blue light from near ultraviolet light with phosphors, and have been actively developed as LCD backlight sources for small portable devices. It is becoming.

As the phosphor for a white LED used for the white LED, the conventional, YAG blue exhibiting fluorescence as a yellow by excitation: Ce ^{3 +} and, (Ba, Sr, Ca) from green to indicate the fluorescence of yellow ^₂ SiO _4: Eu ₂ ^{Although +} , Sr ₃ SiO ₅ : Eu ^{2 +,} and the like are known, higher luminance phosphors are required.

In general, as described in Non-Patent Document 1, a method for synthesizing a phosphor is mixed by wet or dry raw material powder, then put into a baking container and calcined to high temperature, and synthesized by solid phase reaction between the raw materials.

As the activator, for the production of phosphors using Ce ³⁺ , Eu ²⁺ and Tb ³⁺ , heat treatment is generally performed under a reducing atmosphere with an inert gas containing several percent of H ₂ gas. In the high temperature heat treatment, for example, Sr ₃ SiO _5: Eu ^{2 +} in the SrO and SiO ₂ are reacted by configuring the matrix oxide crystals, and the active agent Eu by the reducing atmosphere sintering second horizontal reduction from trivalent, in the host crystal It is replaced with Sr ^{2 +.} Thereby Sr ₃ SiO _5: can be synthesized in the Eu ^{2 +} phosphor.

In general, a high-luminance Sr ₃ SiO _5: It is known that it is necessary to in order to obtain the Eu ^{2 +} phosphor, increasing the crystal phase purity, and uniformly disperse the active agent Eu ^{2 +} in the host crystal. As described in patent document 2, in order to produce a metal oxide by the solid-phase method, baking for a long time at high temperature was required. However, when baking temperature is made high or baking time is lengthened, sintering advances and a particle size will become large. Therefore, in order to reduce the particle size, in the phosphor obtained by pulverizing the sintered product, there is a problem that the luminescence intensity decreases due to damage caused by pulverization.

As a solution of the lowering of the firing temperature and the small particle diameter of the particle diameter, a liquid phase method of preparing a metal oxide precursor using a liquid phase and firing the precursor has been studied. In this liquid phase method, since metal elements are dissolved and mixed in a solvent, homogeneous mixing at the atomic level is possible, and since the solid phase diffusion of the oxide raw material powder such as the solid phase method is not required, synthesis at low temperatures is expected. In addition, the increase in crystal grain diameter can be suppressed by low temperature synthesis.

As an example of such a liquid phase method, there is a precipitation method disclosed in Patent Document 1. In patent document 1, precipitation is produced from a metal salt, tetraethoxysilane (TEOS), and a silica gel, and a fluorescent substance is synthesize | combined by drying and heat processing. Since the metal salt and TEOS do not precipitate at the same time but are only closer to the finer state of the powder raw material mentioned above, there exists a problem that they are not uniformly mixed at an element level.

In Patent Document 2, as a liquid phase method, a precursor is produced by wet synthesis such as citric acid method, coprecipitation method, metal alkoxide method (sol-gel method), thermal decomposition method, complex polymerization method, PVA method or hydrothermal gelation method. The method is described and it is described that these can be compared and the metal oxide fluorescent substance can be synthesize | combined efficiently by using hydrothermal gelation method.

According to Patent Literature 2, when a mixed solution of at least one metal element, TEOS and a solvent is hydrothermally treated, a gel body in which metal elements are uniformly dispersed can be produced, and the composite metal oxide precursor is formed by drying and heat-treating the gel. Occurs. This gel uses the gelling ability of TEOS and is characterized by low organic matter. By hydrothermal gelling the liquid phase mixed at the atomic level, it is possible to produce a uniform precursor. Since the precursor has a short diffusion distance of the element, it is possible to form a complex metal oxide having a uniform chemical composition by heat treatment at a relatively low temperature. However, since the gelation ability of TEOS is used, when the composition ratio of silicon which occupies in a metal component is small, it contains the problem that it cannot contain all the metal element components in a gel.

On the other hand, silicon alkoxides such as TEOS are generally used even when the precursor of the alkaline earth metal silicate-based phosphor is produced by a liquid phase method other than hydrothermal gelation. Using a metal salt and TEOS as a raw material, a homogeneous gel body can be produced by melt | dissolving and mixing these in a suitable solvent. When a non-aqueous solvent is used as the solvent, a uniform mixture can be prepared. However, when water is used as the solvent, since the tetraethoxysilane is hydrophobic, the hydrolysis reaction proceeds at the interface between TEOS and water, and the reaction is locally performed. Since there is a possibility of occurrence, there is a problem that it is difficult to obtain a homogeneous mixture. On the other hand, there is also a problem that non-aqueous solvents, in particular organic solvents, are harmful to the human body and have a risk of ignition.

By the way, the water-soluble silicon compound (WSS) which is a new silicon raw material is disclosed by the nonpatent literature 2 and the patent document 3 in recent years. Since this water-soluble silicon compound substituted four ethoxy groups of TEOS by the propylene glyco group, and has a hydroxyl group, it can exist stably in the acidic aqueous solution of room temperature. The water-soluble silicon compound aqueous solution is hydrolyzed and polycondensed by heating or the like to obtain a SiO ₂ gel. This water-soluble silicon compound is known to have greater gelation ability than TEOS.

In Non-Patent Document 2, it is disclosed that a Mn-added Zn ₂ SiO ₄ phosphor is obtained by mixing a water-soluble silicon compound with a metal zinc raw material aqueous solution, performing a hydrothermal treatment to produce a precursor, and firing in a reducing atmosphere. This phosphor has a 3: 1 ratio of metal element (sum of Zn and Si) to Si, and it is difficult to gel all metal components in TEOS, but it is possible to prepare a gel containing all metal components by using a water-soluble silicon compound. . However, since the hydrothermal synthesis method is essential for preparing the precursor, there is a problem that heat treatment in a pressure vessel such as an autoclave is required.

In this situation, the present inventors found that the (Sr _{1 -y} , Eu _y ) ₃ SiO ₅ phosphor, (Ba _x , Sr _{1 -xy} , Eu _y ) ₃ SiO ₅ , and the metal having a 4: 1 ratio of the metallic element to Si The Eu-activated strontium silicate phosphor precursor was tested by hydrothermal gelation using a water-soluble silicon compound, applied to the preparation of (Ba _x , Sr _1-xy , Eu _y ) ₂ SiO ₄ phosphors in which the ratio of the component element and Si was 3: 1. It was. As a result, it was difficult to contain all the metal components uniformly and all in a gel, and the knowledge that a composition variation and an element distribution nonuniformity were easy to produce was acquired.

Japanese Patent Publication No. 2007-131843 Japanese Patent Laid-Open No. 2008-007390 Japanese Patent Publication No. 2010-7032

Phosphor Handbook, Ohmsa, P.166 N. Takahashi, Y. Suzuki, M. Kakihana, "Synthesis of Zn2SiO4: Mn2 + green emission phosphor by hydrothermal gelation method using a novel water soluble silicon compound", Jounal of the Ceramic Society of Japan, 2009, vol. 117, No. 3, p.313-315

In the present invention, the composition formula (Sr _1-y , Eu _y ) ₃ SiO ₅ (where 0 <Y <0.1), the composition formula (Ba _x , Sr _1-xy , Eu _y ) ₃ SiO ₅ (where 0 <X < 1, 0 <Y <0.1) Eu-activated alkaline earth metal silicate phosphor having a ratio of 4: 1 of all metal constituent elements (Sr, Ba, Eu, Si) and Si to Eu-activated alkaline earth metal silicate phosphor, composition formula (Ba _x , Sr _1-xy , Eu _y ) ₂ Eu-activated alkaline earth metal silicate phosphor of SiO ₄ (where 0 <X <1, 0 <Y <0.1), all metal component elements (Ba, Sr, Eu, Si In the production of Eu-activated alkaline earth metal silicate phosphors having a ratio of 3 to 1) and Si, various technical problems as described above are solved, and precursors having high uniformity in chemical composition are synthesized at a lower temperature than the conventional method. It is possible to manufacture a single-phase high brightness alkaline earth metal silicate phosphor having a uniform chemical composition by heat treating the precursor. To provide a method for the purpose.

The present inventors have intensively studied a result, the composition formula _{(Sr 1 -y, Eu y)} 3 SiO 5 ( stage, 0 <Y <0.1), composition formula _{(Ba x, Sr 1 -xy,} Eu y) one in order to solve the above problems ₃ SiO ₅ (where 0 <X <1, 0 <Y <0.1), composition formula (Ba _x , Sr _{1- xy} , Eu _y ) ₂ SiO ₄ (where 0 <X <1, 0 <Y <0.1) All metal components of strontium, barium, europium, and silicon, which are the constituents of the alkaline earth metal silicate phosphor selected from the group, as an aqueous solution, are mixed, and then maintained at a liquid temperature of 30 ° C. to 100 ° C., thereby making the entire metal uniform. Forming a gel in which the components are distributed, and then drying the gel, heat treatment in the air, and heat treatment in a reducing atmosphere give an alkaline earth metal silicate phosphor having a uniform chemical composition and containing a single phase crystal phase. With knowledge, the present invention has been completed.

That is, the first invention according to the present invention, composition formula (Sr _1-y , Eu _y ) ₃ SiO ₅ (where 0 <Y <0.1), composition formula (Ba _x , Sr _1-xy , Eu _y ) ₃ SiO ₅ (Where 0 <X <1, 0 <Y <0.1), in the group of composition formula (Ba _x , Sr _1-xy , Eu _y ) ₂ SiO ₄ (where 0 <X <1, 0 <Y <0.1) In the method for producing an Eu-activated alkaline earth metal silicate phosphor selected, the following step 1 is included.

[Step 1]

An aqueous solution is produced for each elementary raw material of strontium, barium, europium, and silicon, which is a constituent metal component, and the total amount of all metal components is maintained by maintaining the mixed aqueous solution mixed with the prepared aqueous solution at a liquid temperature of 30 ° C to 100 ° C. A step of forming a gel in this uniformly dispersed state.

According to the second invention according to the present invention, the composition formula (Sr _1-y , Eu _y ) ₃ SiO ₅ (where 0 <Y <0.1), the composition formula (Ba _x , Sr _1-xy , Eu _y ) ₃ SiO ₅ (where , 0 <X <1, 0 <Y <0.1), composition formula (Ba _x , Sr _1-xy , Eu _y ) ₂ SiO ₄ (where 0 <X <1, 0 <Y <0.1) The method for producing an Eu-activated alkaline earth metal silicate phosphor is characterized by including the following steps 1 to 4.

[Step 1]

An aqueous solution was prepared for each elementary raw material of strontium, barium, europium, and silicon, which is a constituent metal component, and the mixed aqueous solution of the prepared aqueous solution was kept at a liquid temperature of 30 ° C to 100 ° C so that the entire amount of all the metal components was uniform. Process of forming gel in dispersed state.

[Step 2]

A step of drying the gel formed in step 1 to form a dried product and removing the solvent contained.

[Step 3]

Heat-treating the dried material in step 2 in an air atmosphere to remove organic matter and obtaining a calcined powder.

[Step 4]

A step of obtaining the phosphor powder by heat-treating the calcined powder formed in step 3 in a reducing atmosphere.

The 3rd invention which concerns on this invention makes concentration of strontium, barium, and europium which are the constituent metal components in the mixed aqueous solution in the process 1 of 1st invention or 2nd invention being 1 mol / L-5.5 mol / L, It is characterized by the above-mentioned. Is a method for producing an Eu-activated alkaline earth metal silicate phosphor.

In the 4th invention which concerns on this invention, after the aqueous solution of the silicon raw material in the process 1 of 1st invention or 2nd invention adds 1,2-propanediol to tetramethoxysilane, it heats, stirs, and mixes, It is a water-soluble silicon aqueous solution which added hydrochloric acid, The manufacturing method of the Eu activated alkaline-earth metal silicate fluorescent substance characterized by the above-mentioned.

According to a fifth aspect of the present invention, a Eu-activated alkaline earth metal silicate comprising the step of removing coarse particles of 100 µm or more by classification from the calcined powder formed in step 3, following step 3 of the second invention. It is a manufacturing method of fluorescent substance.

According to the present invention, the composition formula (Ba _x , Sr _{1 -xy} , Eu _y ) ₂ SiO ₄ (where 0 <X <1) in which the ratio of the total metal component elements (Ba, Sr, Eu, Si) and Si is 3: 1 , 0 <Y <0.1) Eu activated alkaline earth metal silicate phosphor, compositional formula (Sr _{1 -y} , Eu _y ) ₃ SiO ₅ with a ratio of 4: 1 of all metal elements (Sr, Ba, Eu, Si) and Si (Where 0 <Y <0.1) and composition formula (Ba _x , Sr _{1 -xy} , Eu _y ) ₃ SiO ₅ (where 0 <X <1, 0 <Y <0.1) of Eu-activated alkaline earth metal silicate phosphor In manufacturing, it is possible to synthesize a precursor having a high uniformity of chemical composition at a lower temperature than the conventional method, and by heat-treating the precursor, a single-phase high-brightness Eu activated alkaline earth metal silicate phosphor having a uniform chemical composition can be efficiently produced. Can be.

In addition, according to the production method of the present invention, since the gel containing all the metal components uniformly is synthesized without the need for a pressure vessel such as an autoclave, the production cost is remarkably reduced, so the industrial significance is large.

1 is a diagram illustrating an X-ray diffraction pattern of a sample of Example 1. FIG.
FIG. 2 shows the fluorescence spectra of Examples 1 and 6, together with commercially available YAG: Ce (a conventional spectrum) for comparison.
FIG. 3 shows the fluorescence spectra of Example 7, Comparative Example 8 and Comparative Example 9, together with commercially available YAG: Ce (a conventional spectrum).

Hereinafter, the embodiments of the present invention will be described in detail. However, the embodiments described below represent representative examples of the present invention, and the present invention is not limited to these embodiments unless the gist of the present invention is eliminated.

First, the manufacturing process of Eu activated alkaline-earth metal silicate fluorescent substance is demonstrated.

The manufacturing process of the Eu activated alkaline-earth metal silicate fluorescent substance of this invention mixes the aqueous solution of each element raw material of strontium, barium, europium, and silicon which are constituent metal components (henceforth a raw material aqueous solution), and is 30 degreeC. Step 1 of forming a transparent gel in which the silicon raw material is heated to a temperature of 30 ° C.-100 ° C. to form a transparent gel containing all the other metal components of strontium, barium and europium and uniformly dispersed in a total amount by maintaining the liquid temperature at −100 ° C., Process 2 which obtains the dried material from which the solvent was removed by drying the transparent gel formed in the process 1, Then, process 3 which heat-processes this dry matter in air | atmosphere to obtain Eu activated alkaline-earth metal silicate phosphor precursor as calcining component, and 100 if needed. Eu-activated alkaline earth metal by the step of classifying and removing coarse particles of 탆 or more and heat treatment in a reducing atmosphere And a step 4 of forming a re-locate the phosphor.

Hereinafter, the said process 1-process 4 are explained in full detail.

[Step 1]

In this step, after mixing raw material aqueous solutions of strontium, barium, europium, and silicon, which are constituent metal components, the mixture is kept at a temperature of 30 ° C to 100 ° C, and the entire amount of all the metal components of strontium, barium, europium, and silicon is uniform. It is a process of obtaining a dispersed gel.

In this step 1, first, a raw material aqueous solution of all metal components of strontium, barium, europium, and silicon is prepared. The strontium raw material is not particularly limited as long as it is dissolved in water and the pH of the aqueous solution is 7 or less, and chlorides, oxides, acetates, nitrates, carbonates, sulfates, oxalates, and the like of strontium can be used. In particular, since the anion component can be easily removed by heating, it is preferable to use nitrate, acetate, carbonate, oxalate or the like. When dissolving the metal salt, hydroxycarboxylic acids such as citric acid, lactic acid and malic acid may be added. In this case, since the compositional deviation from injection can be suppressed, it is preferable to set it as the aqueous solution of the carbonate whose solubility is small compared with nitrate etc. The barium raw material and the europium raw material are also similar to the strontium raw material. In addition, the raw material aqueous solution of strontium, barium, and europium may be separately prepared and mixed, and the mixed aqueous solution may be produced in one container from the beginning.

Next, in this invention, the well-known water-soluble silicon compound mentioned above is used as a silicon raw material. If the pH of the aqueous solution is greater than 7, the water-soluble silicon compound may immediately start gelling, resulting in the formation of an uneven gel body. If the pH is less than 1, gelling is difficult, so the pH is in the range of 1 to 7.

In addition, when there is too much water with respect to the metal element of a component, since a gel and a liquid separate two layers and a metal ion elutes in a liquid phase, there exists a possibility that a gel may become a nonuniform composition. If the amount of water is too small relative to the metal element, a uniform aqueous solution may not be produced, and the metal may be precipitated before forming the gel, resulting in a non-uniform gel. In the present invention, it is indispensable to uniformly disperse all metal element elements. For this reason, it is important to make metal element concentration into 1 mol / L-5.5 mol / L at the time of making aqueous solution for this. Preferably it is 2 mol / L-5.5 mol / L.

Here, about the specific manufacturing conditions of a water-soluble silicon compound, it can manufacture by the method as described in the manufacture example of patent document 3. That is, 1,2-propanediol (0.4 mol) is added to tetramethoxysilane (0.1 mol), and the mixture is mixed for 24 hours while stirring using a hot stirrer so that the liquid temperature becomes 54 ° C. Then, hydrochloric acid (0.0001 mol) is added, and it mixes further at liquid temperature of 54 degreeC for 1 hour, and water-soluble silicon aqueous solution can be obtained. In addition, although patent document 3 describes the water-soluble silicon compound of various types to manufacture examples 1-9, all can be used by this invention.

Next, each aqueous solution prepared on the said conditions is mixed, it is stirred for 30 minutes-1 hour at room temperature, the obtained solution is put into a container, it is maintained at the temperature of 30 degreeC-100 degreeC, and a uniform gel body is obtained. If the temperature is lower than 30 ° C, gelation takes time. If the temperature exceeds 100 ° C and water boils, drying and gelation occur at the same time. Therefore, it is important to set the temperature to 30 ° C to 100 ° C. Moreover, it is more preferable to set it as 50 degreeC-100 degreeC. Gelation time is not specifically limited, What is necessary is just time to gelatinize whole, and the uniform gel is obtained about 24 hours normally.

Although a container is not specifically limited, What has heat resistance to heating temperature, such as glass, polypropylene, and polytetrafluoroethylene, can be used.

[Step 2]

Step 2 is a step of removing the solvent from the gel obtained in step 1 to obtain a dried product.

Removal of this solvent is easy by heating. Since the solvent component contained in a gel is water, ethanol, and propylene glycol, 100 to 120 degreeC is preferable. Although heating time also depends on a sample amount, about 1 to 6 hours are preferable.

[Step 3]

Step 3 is a step of thermally removing the organic matter from the solid obtained in Step 2 in the air, pyrolysing and removing the organic material to further obtain a calcined powder which is a precursor of the Eu activated alkaline earth metal silicate phosphor.

The heat treatment in the atmosphere is aimed at further decomposing the organic matter contained in the raw material, removing carbon generated by the decomposition, and crystal growth of the oxide mother crystal of the Eu activated alkaline earth metal silicate phosphor.

The conditions of the heat treatment in the air are performed at a temperature of 400 ° C to 1600 ° C. In addition, although this heat processing may be performed by one heat processing, and may be divided into multiple times, When heat-processing over several times, it is preferable to disintegrate by induction at the time of every heat processing.

In the details of this heat treatment, first of all, decomposition of an organic substance is to evaporate, pyrolyze, or burn propylene glycol, hydroxycarboxylic acid, or the like contained in the raw material. In order to burn the organic substance, a temperature of 400 ° C. or higher is required in the air. In addition, when only the decomposition of an organic substance is performed, it is preferable to carry out in 400 degreeC-600 degreeC atmosphere.

The following carbon removal completely removes the carbon produced during the decomposition of the above-mentioned organic matter. When the metal element is carbonated, it is decomposed. Carbon cannot be removed at a temperature lower than 700 ° C., and melting or sintering may occur when it exceeds 1300 ° C., so that the heat treatment time is performed in consideration of heat treatment time at a temperature exceeding 1300 ° C. When carbon is removed alone, heat treatment in a temperature range of 700 ° C to 1300 ° C is preferred.

In addition, when producing an oxide matrix crystal, it bakes in air | atmosphere.

In the firing temperature, when the oxide mother crystal is Sr ₃ SiO ₅ , it is difficult to obtain a crystalline phase at a temperature lower than 1300 ° C., and reacts with an alumina crucible at a temperature exceeding 1600 ° C., therefore, a temperature range of 1300 ° C. to 1600 ° C. is preferable. Do. Especially preferably, it is 1450 degreeC-1550 degreeC. If this heat treatment temperature is too low, an abnormal Sr ₂ SiO ₄ phase is generated as an impurity, which lowers the luminescence intensity of the finally obtained phosphor, which is not preferable. If this heat treatment temperature is too high, it becomes difficult to obtain a powdery phosphor without sintering or melting the Sr ₃ SiO ₅ crystals. Crushing the phosphor damages the crystal, which is not desirable to obtain a high luminance phosphor.

When the oxide mother crystal is (Ba _x , Sr _{1 -x} ) ₃ SiO ₅ , (Ba _x , Sr _{1 -x} ) ₂ SiO ₄ , it is difficult to obtain a crystal phase at a temperature lower than 1000 ° C., and the temperature exceeds 1600 ° C. Since it reacts with an alumina crucible, the temperature range of 1000 degreeC-1400 degreeC is preferable. Especially preferably, it is 1200 degreeC-1350 degreeC.

If the heat treatment temperature is too low, the BaCO ₃ phase or the SrCO ₃ phase which is similar to the above remains as unreacted impurities, which is not preferable because the luminous intensity of the finally obtained phosphor is lowered. On the contrary, when this heat processing temperature is too high, it is necessary to sinter, melt | dissolve, or obtain powder-like fluorescent substance by pulverization. In addition, since pulverizing the phosphor damages the crystal, it is not preferable to obtain a high luminance phosphor.

The heat treatment time is 1 to 24 hours, preferably 2 to 4 hours. If the heat treatment time is short, the reaction for producing the parent crystal becomes insufficient, the crystal phase purity is low, and the emission intensity is low. If the heat treatment time is long, sintering proceeds to produce coarse particles that are firmly sintered or adhere to the container, which is not preferable.

The above heat treatment may be performed by a plurality of heat treatments, may be performed by one heat treatment under optimum conditions, or may be performed by one heat treatment cycle while continuously changing to heat treatment conditions suitable for individual heat treatments.

In addition, in the case where the oxide mother crystal is Sr ₃ SiO ₅ , when the above-mentioned Sr ₂ SiO ₄ phase is produced, since it is easier to sinter at a lower temperature than the Sr ₃ SiO ₅ phase, it is coarsened by firing in a reducing atmosphere of the subsequent step 4. Since particles are further produced and the fluorescence properties are lowered, it is preferable to remove coarse particles of 100 µm or more in advance by classification.

[Step 4]

Step 4 is a step of obtaining a phosphor by heat-treating the calcined powder obtained in Step 3 in a reducing atmosphere and replacing Eu ²⁺ with divalent strontium ions or divalent barium ions in the parent crystal. The calcined powder used herein may be an oxide obtained by completely decomposing carbonate in Step 3, or may be a calcined powder containing a part of carbonate.

The temperature (firing temperature) of the heat treatment differs depending on the composition, the firing conditions, the sintering flux, and the like. However, when the oxide mother crystal is Sr ₃ SiO ₅ , it is 1300 ° C to 1600 ° C, preferably 1450 ° C to 1550 as in Step 3 It is set to ° C.

In addition, when the oxide mother crystal is (Ba _x , Sr _{1 -x} ) ₃ SiO ₅ , (Ba _x , Sr _{1 -x} ) ₂ SiO ₄ , it is 1000 ° C.-1400 ° C., preferably 1000 ° C. similarly to step 3. It is 1350 degreeC.

As the reducing atmosphere, 1 vol% of an inert gas such as N ₂ or Ar? May be used a gas mixture of H ₂ of 10 vol%.

As mentioned above, the high brightness | luminance Eu activated alkaline-earth metal silicate fluorescent substance which the purity of the target crystal phase is high, and a component component is uniformly well-dispersed through said "process 1"-"process 4" can be manufactured.

In addition, the method for producing an Eu-activated alkaline earth metal silicate phosphor of the present invention is applicable to the case where an oxide mother crystal is a composition formula Sr ₂ SiO ₄ or when an alkaline earth silicate phosphor containing another alkaline earth metal element is produced in the composition. You can expect by fully considering what you can do.

[Example]

Hereinafter, the present invention will be described in detail by way of examples.

A Eu activated alkaline earth metal silicate fluorescent substance, the composition formula _{(Sr 1-y, Eu y} ) 3 SiO 5 ( stage, 0 <Y <0.1) by using a yellow phosphor, shows a method of manufacturing the same.

The water-soluble silicon compound referred to Production Example 1 (water-soluble silicon compound A) described in paragraph [0046] of Patent Document 3.

Confirmation and semi-quantification of the crystal phase of the produced phosphor were carried out by X-ray diffraction and Rietveld analysis.

Evaluation of the composition deviation was made by quantitative analysis by ICP emission analysis of each element.

Evaluation of the luminescence property was carried out using the fluorescence spectrophotometer FP-6500 (manufactured by Nihon Bunco Co., Ltd.), and the emission spectrum was measured. In addition, the emission spectrum is measured with an excitation light wavelength of 455 nm, and the excitation spectrum is measured at the peak wavelength of the emission spectrum.

Example 1

Eu-activated strontium silicate phosphors of composition formula (Sr _1-y , Eu _y ) ₃ SiO ₅ (where 0 <Y <0.1) were prepared under the following process conditions.

[Step 1]

₃ SrCO as a metal element compound (manufactured by Kanto Chemical whether or 3N, liver _{production), Eu (NO 3) 3} 6H 2 O (3N, Miss manufactured by Wakamatsu is as to whether or kuya kuhing), an adjustable (Sr _{1 -? Y} Eu _y ) ₃ SiO ₅ and weighed so that y = 0.01. To an aqueous solution of citric acid (98.0%, manufactured by Wako Pure Chemical Industries, Ltd.), SrCO ₃ was weighed in such a way that the total concentration of strontium and europium (hereinafter referred to as the aqueous solution of metal salt (Sr + Eu)) was 4.0 mol / L. The transparent solution was obtained by stirring at 40 degreeC for 1 hour. In addition, the weighed Eu (NO ₃ ) _{3 ˜} 6H ₂ O was dissolved in water to obtain an aqueous solution.

Next, 1,2-propanediol (0.4 mol) was added with respect to tetramethoxysilane (0.1 mol), and the water-soluble silicon compound was mixed for 24 hours, stirring using a heating stirrer so that liquid temperature might be 54 degreeC. . Thereafter, hydrochloric acid (0.0001 mol) was added, mixed with a water-soluble silicon compound at a liquid temperature of 54 ° C, combined with an SrCO ₃ solution, stirred and mixed for 30 minutes at room temperature, and a transparent mixed solution was obtained.

The mixed solution prepared as described above was placed in a polypropylene container, covered with a cap, sealed, and kept at 50 ° C for 24 hours to obtain a transparent gel. This gel had elasticity but was not separated into two layers, and was in a uniform state in appearance.

[Step 2]

The transparent gel obtained in step 1 was kept at 120 ° C. for 6 hours in a drier, and the solvent in the gel was removed to obtain a dried gel. The dried gel was a clear solid.

[Step 3]

The dried gel obtained in step 2 was pulverized with agate induction, heat treated at 550 ° C. for 3 hours in an air atmosphere in an electric furnace, taken out and crushed, and then heat treated again at 800 ° C. for 3 hours. After further taking out and pulverizing, the mixture was kept at 1200 ° C for 3 hours, and then heated to 1500 ° C, held for 3 hours, heat-treated in an atmospheric atmosphere, taken out and pulverized, and coarse particles of 100 µm or more were removed by classification. The calcined portion was obtained.

[Step 4]

The calcined powder obtained in step 3 was placed in a molybdenum container and subjected to heat treatment while flowing a 4% H ₂ + 96% Ar mixed gas at 1500 ° C. for 3 hours in a tungsten heater electric furnace to obtain a powder in powder form. .

About the obtained fluorescent substance powder, the result of having measured X-ray diffraction is shown in FIG. Moreover, the result of having measured the fluorescence characteristic is shown in FIG.

In the X-ray diffraction result of FIG. 1, it was found that the obtained phosphor powder was approximately single phase of Sr ₃ SiO ₅ . Moreover, in the fluorescent characteristic of FIG. 2, a wide excitation absorption was seen over 300 nm-500 nm, showed a peak near 585 nm, and yellow light emission was confirmed. The emission spectrum is sharper than YAG: Ce shown for comparison, and the emission peak intensity, emission peak area, and both are high, and the luminance of composition formula (Sr _1-y , Eu _y ) ₃ SiO ₅ (where 0 <Y <0.1) Eu activated strontium silicate phosphors were obtained.

Example 2

In Example 1, phosphor powder was produced in the same manner as in Example 1 except that the total aqueous solution concentration of strontium and europium was 2.0 mol / L. The results are shown in Table 1.

Example 3

A phosphor powder was prepared in the same manner as in Example 1 except that the total aqueous solution concentration of strontium and europium was changed to 5.5 mol / L in Example 1. The results are shown in Table 1.

(Comparative Example 1)

In Example 1, phosphor powder was produced in the same manner as in Example 1 except that the total aqueous solution concentration of strontium and europium was set to 0.1 mol / L. The results are shown in Table 1.

(Comparative Example 2)

In Example 1, phosphor powder was produced in the same manner as in Example 1 except that the total aqueous solution concentration of strontium and europium was 0.15 mol / L. The results are shown in Table 1.

(Comparative Example 3)

In Example 1, phosphor powder was produced in the same manner as in Example 1 except that the total aqueous solution concentration of strontium and europium was 0.2 mol / L. The results are shown in Table 1.

(Comparative Example 4)

In Example 1, phosphor powder was produced in the same manner as in Example 1 except that the total aqueous solution concentration of strontium and europium was 6.0 mol / L. The results are shown in Table 1.

From Table 1, when the metal salt (Sr + Eu) aqueous solution concentration is low, two layers are isolate | separated, and when the amount of water isolate | separated from the gel increases, and when the metal salt (Sr + Eu) aqueous solution concentration becomes high, two layers are not separated and it is uniform. It is clear that a clear gel in the phosphorus state is obtained. In addition, in the metal salt (Sr + Eu) aqueous solution concentration of 6 mol / L (Comparative Example 4), the metal salt could not be completely dissolved. From this, in order to disperse a metal component element (Sr + Eu) uniformly in a gel, it is preferable to make metal salt (Sr + Eu) aqueous solution concentration into 1 mol / L-5.5 mol / L, Preferably it is 2 mol / L It is preferable to set it to 5.5 mol / L.

Example 4

A phosphor powder was produced in the same manner as in Example 1 except that the holding temperature was 80 ° C during gelation in Step 1 of Example 1. Table 2 shows the results of visually observing the gelation state of the sample.

In addition, the criterion of gelation shown in Table 2 was "(circle)" when fluidity was lost when the container was moved or inverted, and "x" when there was still fluidity.

Example 5

A phosphor powder was produced in the same manner as in Example 1 except that the holding temperature was 100 ° C during gelation in Step 1 of Example 1. Table 2 shows the results of visually observing the gelation state of the sample.

(Comparative Example 5)

A phosphor powder was produced in the same manner as in Example 1 except that the holding temperature was 25 ° C during gelation in Step 1 of Example 1. Table 2 shows the results of visually observing the gelation state of the sample.

(Comparative Example 6)

A phosphor powder was produced in the same manner as in Example 1 except that the holding temperature was 25 ° C. and the holding time was 96 hours during gelation in Step 1 of Example 1. Table 2 shows the results of visually observing the gelation state of the sample.

From Table 2, if the holding temperature at the time of gelation was 25 ° C., the gel was still fluid even after holding for 24 hours and remained fluid even when extended for 96 hours, and did not become a uniform state. On the other hand, in the range of 50 ° C to 100 ° C, a transparent gel was obtained in a uniform state without being separated in two layers.

(Comparative Example 7)

In the process 2 of Example 1, the transparent mixed solution was put into the container made of polytetrafluoroethylene, it was further put into the stainless steel pressure vessel, sealed, and it hold | maintained at 200 degreeC for 24 hours, and gelatinized. The obtained sample consisted of a gel and a liquid, and was separated into two layers.

The weight of the liquid separated from this gel was 20 mass% of the whole. About the gel dry powder obtained by Example 1 and the comparative example 7, the component (Sr, Eu, Si) was analyzed, and the result which compared the deviation with the injection composition is shown in Table 3.

From Table 3, it can be seen that the ratio of the amount of Sr to the total amount of Sr, Si, and Eu contained in the gel of Comparative Example 7 is slightly different from the injection composition, and the ratio of the amount of Si is large.

As described above, the holding temperature at the time of gelation is important in the present invention, and is an important factor for the formation of a uniform composition.

[Comparison of quantum efficiency]

Table 4 shows the results obtained by measuring the quantum efficiency in the fluorescence characteristics (luminescence spectrum measured at an excitation light wavelength: Ex = 455 nm) of the phosphor particles obtained in Example 1 using an integrating sphere. For comparison, general YAG: Ce was measured together as a general yellow phosphor as a conventional example.

From Table 4, it can be seen from Example 1 that the internal quantum efficiency is very high at 71.1%, which is superior to the conventional YAG: Ce phosphor.

Example 6

Next, Eu activated alkaline earth metal silicate phosphors of the composition formula (Ba _x , Sr _{1 -xy} , Eu _y ) ₃ SiO ₅ (where 0 <X <1, 0 <Y <0.1) were prepared under the following process conditions. .

In Example 1, when strontium carbonate was weighed, a phosphor powder was produced in the same manner as in Example 1 except that strontium carbonate and barium carbonate were set to a molar ratio of Sr: Ba of 0.86: 0.13. Namely, it is an Eu activated alkaline earth metal silicate phosphor represented by the composition formula (Ba _0.86 , Sr _0.13 , Eu _0.01 ) ₃ SiO ₅ .

X-ray diffraction was measured on the obtained phosphor powder, and it was found that carbonate and other impurity phases were not seen, and the phosphor powder was approximately single phase. In addition, when the fluorescence properties were measured, as shown in Fig. 2, excitation absorption having a peak near 350 nm was observed, and the emission showed a peak near 600 nm, and the orange color emission was confirmed.

Thus, Eu-activated alkaline earth metal silicate phosphor of high brightness composition formula (Ba _x , Sr _1-xy , Eu _y ) ₃ SiO ₅ was obtained.

Example 7

Eu-activated alkaline earth metal silicate phosphor of composition formula (Ba _x , Sr _1-xy , Eu _y ) ₂ SiO ₄ was prepared under the following process conditions.

[Step 1]

As a metal element compound, BaCO ₃ (3N, manufactured by Kanto-Kagaku Co., Ltd.), SrCO ₃ (3N, manufactured by Kanto-Kagaku Co., Ltd.), and Eu ₂ O ₃ (3N, manufactured by Furuuchi Kaka-Ku), are represented by the formula (Ba _x , Sr _{1 -xy} , Eu _y ) ₂ SiO ₄ and weighed so that x = 0.69 and y = 0.08. BaCO ₃ weighed in an aqueous solution of citric acid (98.0%, manufactured by Wako Pure Chemical Industries, Ltd.) to have a total concentration of barium, strontium, and europium (hereinafter referred to as an aqueous metal salt (Sr + Eu) solution concentration) of 4 mol / L. And SrCO ₃ were added and the transparent solution was obtained by stirring at 40 degreeC for 1 hour. Further, a Eu (NO3) weighing _3? 6H ₂ O dissolved in water to obtain an aqueous solution.

Next, 1,2-propanediol (0.4 mol) was added with respect to tetramethoxysilane (0.1 mol), and the water-soluble silicon compound was mixed for 24 hours, stirring using a heating stirrer so that liquid temperature might be 54 degreeC. . Then hydrochloric acid (0.0001 mol) is added and mixed with a water-soluble silicon compound at a liquid temperature of 54 ° C., BaCO ₃ The solution and SrCO ₃ solution were combined and stirred and mixed at room temperature for 30 minutes to obtain a transparent mixed solution.

The mixed solution prepared as described above was placed in a polypropylene container, covered with a cap, sealed, and kept at 50 ° C for 24 hours to obtain a transparent gel. This gel had elasticity but was not separated into two layers, and was in a uniform state in appearance.

[Step 2]

The transparent gel obtained in the step 1 was kept at 120 ° C. for 6 hours in a dryer, and the solvent in the gel was removed to obtain a dried gel. The dried gel was a clear solid.

[Step 3]

The dried gel obtained in step 2 was pulverized with agate induction, and heat-treated at 550 ° C. for 3 hours in an air atmosphere using an electric furnace, taken out and pulverized, and then heat-treated again at 800 ° C. for 3 hours. After further taking out and crushing, it heat-treated in the atmospheric atmosphere hold | maintained at 1200 degreeC for 6 hours, was taken out and pulverized, and the calcined powder was obtained.

[Step 4]

The calcined powder obtained in step 3 was placed in a molybdenum container and subjected to heat treatment while flowing a 4% H ₂ + 96% Ar mixed gas at 1200 ° C. for 3 hours using a tungsten heater electric furnace to obtain powdery phosphor powder.

X-ray diffraction was measured on the obtained phosphor powder, and it was found that no carbonate or other impurity phase was found, and the phosphor powder was approximately single phase. 3 shows the results of measuring fluorescence characteristics.

In the fluorescence characteristics of FIG. 3, excitation absorption with a peak near 370 nm was observed, and luminescence exhibited a peak near 529 nm, and green emission was confirmed. A Eu-activated alkaline earth metal silicate phosphor of high brightness composition formula (Ba _x , Sr _1-xy , Eu _y ) ₂ SiO ₄ was obtained.

(Comparative Example 8)

The composition formula (Ba _x , Sr _{1 -xy} , Eu) was the same as in Example 7 except that the heat treatment temperature in the atmospheric atmosphere of Step 3 was 1300 ° C., and the heat treatment temperature in the reducing atmosphere of Step 4 was 1300 ° C. _y ) Eu activated alkaline earth metal silicate phosphor of ₂ SiO ₄ was synthesized. After step 4, the sample was firmly sintered and required grinding to obtain a powdery sample. The fluorescence properties of the sample after pulverization were evaluated. As shown in FIG. 3, excitation absorption with a peak near 370 nm was observed as in Example 7, and the emission showed a peak near 529 nm, but the sample of Example 7 It turned out that luminous intensity is inferior.

(Comparative Example 9)

The composition formula (Ba _x , Sr _{1 -xy} , Eu) was the same as in Example 7 except that the heat treatment temperature in the atmospheric atmosphere of Step 3 was 1000 ° C., and the heat treatment temperature in the reducing atmosphere of Step 4 was 1000 ° C. _y ) Eu activated alkaline earth metal silicate phosphor of ₂ SiO ₄ was synthesized.

The fluorescence characteristics of the sample were evaluated, and as shown in FIG. 3, excitation absorption with a peak near 370 nm was observed as in Example 7, and the luminescence exhibited a peak near 529 nm, but was larger than the sample of Example 7. It turned out that luminous intensity is inferior.

As described above in the Examples and Comparative Examples, according to the preparation method of the Eu-activated strontium silicate phosphor having the compositional formula (Sr _{1- y} , Eu _y ) ₃ SiO ₅ (where 0 <Y <0.1) of the present invention, It is possible to obtain a high luminance yellow phosphor having a broad excitation absorption over blue and a light emitting band around 585 nm.

In addition, according to the preparation method of Eu-activated alkaline earth metal silicate phosphor of composition formula (Ba _x , Sr _1-xy , Eu _y ) ₃ SiO ₅ (where 0 <X <1, 0 <Y <0.1), From this, a high-luminance orange phosphor having a broad excitation absorption over blue and having a light emitting band around 600 nm can be obtained.

In addition, according to the preparation method of Eu-activated alkaline earth metal silicate phosphor of composition formula (Ba _x , Sr _1-xy , Eu _y ) ₂ SiO ₄ (where 0 <X <1, 0 <Y <0.1), It is possible to obtain a high luminance green phosphor having a broad excitation absorption over blue and having a light emitting band around 529 nm.

Claims (5)

Composition (Sr _1-y , Eu _y ) ₃ SiO ₅ (where 0 <Y <0.1), Composition Formula (Ba _x , Sr _1-xy , Eu _y ) ₃ SiO ₅ (where 0 <X <1, 0 < Y <0.1), Preparation of Eu Activated Alkaline Earth Metal Silicate Phosphors Selected from the Groups of Formulas (Ba _x , Sr _1-xy , Eu _y ) ₂ SiO ₄ (where 0 <X <1, 0 <Y <0.1) In the method,
A process for producing an Eu activated alkaline earth metal silicate phosphor, comprising the following step 1.
[Step 1]
An aqueous solution is produced for each elementary raw material of strontium, barium, europium, and silicon, which is a constituent metal component, and the total amount of all metal components is maintained by maintaining the mixed aqueous solution mixed with the prepared aqueous solution at a liquid temperature of 30 ° C to 100 ° C. A step of forming a gel in this uniformly dispersed state. Composition Formula (Sr _{1 -y} , Eu _y ) ₃ SiO ₅ (where 0 <Y <0.1), Composition Formula (Sr _{1 -y} , Eu _y ) ₃ SiO ₅ (where 0 <Y <0.1) (Ba _x , Sr _{1 -xy} , Eu _y ) ₃ SiO ₅ (where 0 <X <1, 0 <Y <0.1), composition formula (Ba _x , Sr _{1 -xy} , Eu _y ) ₂ SiO ₄ (where 0 <X <1 In the method for producing an Eu-activated alkaline earth metal silicate phosphor selected from the group of 0, 0 <
A process for producing an Eu-activated alkaline earth metal silicate phosphor comprising the following steps 1 to 4.
[Step 1]
An aqueous solution is prepared for each elementary material of strontium, barium, europium, and silicon, which is a constituent metal component, and the total amount of all metal components is uniformly maintained by maintaining the mixed aqueous solution mixed with the prepared aqueous solution at a liquid temperature of 30 ° C to 100 ° C. Process of forming gel in dispersed state.
[Step 2]
Drying the gel formed in step 1 to form a dried product, and removing the solvent contained therein.
[Step 3]
Process of heat-processing the dried material in process 2 in air | atmosphere atmosphere, removing an organic substance, and obtaining a calcined powder.
[Step 4]
A step of obtaining the phosphor powder by heat-treating the calcined powder formed in step 3 in a reducing atmosphere. The Eu-activated alkaline earth according to claim 1 or 2, wherein the concentrations of strontium, barium and europium which are constituent metal components in the mixed aqueous solution in the step 1 are 1 mol / L to 5.5 mol / L. Method for producing a metal silicate phosphor. The aqueous solution of the silicon raw material in the said process 1 is a water-soluble silicon of Claim 1 or 2, after adding 1,2-propanediol to tetramethoxysilane, heating, stirring, and mixing, and then adding hydrochloric acid. A method for producing an Eu-activated alkaline earth metal silicate phosphor, which is an aqueous solution. The method for producing an Eu-activated alkaline earth metal silicate phosphor according to claim 2, further comprising a step of removing coarse particles of 100 µm or more from the calcined powder formed in the step 3 after the step 3 by classification.

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