KR20020077998A - Spherical shape red color luminescence composition - Google Patents

Abstract

PURPOSE: Provided is a spherical red light emitting phosphor which shows uniform spherical particle size, which is produced by forming a phosphor material by coprecipitation, pyrolyzing and heat treating the phosphor material. CONSTITUTION: The phosphor is produced by the steps of (i) dissolving each phosphor material selected from the group consisting of soluble yttrium salt such as Y(NO3)3, Y2(SO4)3, YCl3, a boron compound, such as ammonium borate, potassium borate, sodium borate, lithium borate, and a soluble europium salt such as Eu(NO3)3, Eu2(SO4)3, EuCl3, in water; (ii) mixing the resulting aqueous solution of phosphor material with stirring, so as to obtain hydrate of the phosphor material; (iii) pyrolyzing the hydrate in a high pressure reactor at 150-250 deg.C for 6-48 hours, and sintering the pyrolyzed hydrate in neutral or reducing atmosphere at 800-1100 deg.C for 1-6 hours.

Description

Spherical shape red color luminescence composition

The present invention relates to a spherical red light emitting phosphor. More specifically, the present invention relates to a spherical red light-emitting phosphor having a spherical uniform particle size by a pyrolysis and heat treatment process after preparing a phosphor raw material by coprecipitation method.

In general, phosphors are particles having a particle diameter of several microns, and are used by attaching phosphor particles to a vitreous surface to be formed using an organic binder or the like as a medium.

In the conventional case, the phosphor particles are obtained by mixing the raw material mixture in a predetermined ratio into a composition and sintering the composition in an electric furnace for several hours. The production of the phosphor by sintering in an electric furnace takes a long time, and there is a problem in that the productivity decreases. To improve such a sintering process, Japanese Patent Application No. 45-37296 and Japanese Patent Application No. 52-37581 are used as raw materials for the phosphor. After melt | dissolving the raw material mixture used, the technique of spraying a molten fluorescent material raw material using a nozzle and manufacturing into granular form is demonstrated. Japanese Patent Laid-Open No. 62-201989, which applies a ceramic manufacturing technique to the manufacture of phosphors, describes a method of manufacturing a phosphor by melting a phosphor raw material using a high frequency plasma, and in a similar manner, Korean Patent Publication No. 2000-73329 (patent application) No. 1999-16555) describes a method for producing a phosphor by ultrasonic spray pyrolysis. However, these conventional methods are still not practical in industry. For example, in Japanese Unexamined Patent Publications No. 45-37296 and Japanese Unexamined Patent Publication No. 52-37581, since the heating source is a liquid combustion salt, it is easy to oxidize the phosphor raw material, but it is not suitable for the reaction for reducing or decomposing the phosphor raw material. In addition, in Japanese Patent Application Laid-Open No. 62-201989, it is easy to maintain and control the atmosphere during the reaction as oxidizing, reducing, or neutral when melting the phosphor raw material using a high frequency plasma. It had to be used and not practical. In addition, the phosphor particles produced by the ultrasonic spray pyrolysis method described in Korean Patent Publication No. 2000-73329 are hollow particles in the form of hollows, and the phosphors are broken during the processing in a later process. There are some restrictions on controlling what is required. In addition, the recovery of the powder formed by the ultrasonic spray is relatively difficult, the yield is low, there are problems to apply industrially. In addition, the liquid phase method has been studied a lot to solve the problems of the solid phase method. (See Ravichandran D., Journal of Luminescence, 71, 291-297, 1997 and Korean Patent No. 254169, etc.). Unlike the solid phase method, liquid phase methods such as coprecipitation method and sol-gel method have the advantage of producing a desired phosphor at a very low temperature, and because the doping material can be mixed at the molecular level, good fluorescence at a lower heat treatment temperature is possible. You can expect the characteristics. However, oxide phosphors produced by the liquid phase method also have a problem that it is difficult to use for displays requiring a uniform size and shape because the shape of the particles is very uneven.

The effect obtained by making a fluorescent substance spherical is demonstrated as follows by taking a fluorescent lamp as an example.

First, the bulk density is large. That is, they are the same weight but have a smaller apparent volume and can be stored in a small container.

Second, liquidity is good. The suspension is easy to disperse when making a suspension. Therefore, a fluorescent film with a small amount of film defects due to aggregates and uniformity and a high filling rate can be obtained, and the film thickness per weight becomes thinner as compared with conventional fluorescent materials. Thin membranes generally do not peel off well.

Third, the adhesion rate of the phosphor can be easily changed by using a spherical phosphor that is easy to control physical properties when applied using the suspension.

Fourth, the specific surface area of the phosphor is small, and the portion where the surface of the particle is likely to deteriorate is reduced, so that it is possible to control thermal deterioration in the process and change in luminescence properties over time.

Fifth, since the specific surface area is small, the degassing of the heat treatment process or the heat exhaust process is facilitated, and the gas emission is reduced during the operation of the fluorescent lamp.

Sixth, the diffusion transmittance in the phosphor is increased, and as a result, the scattering loss is small and there is a possibility of improving the luminous flux.

Therefore, the present inventors have been devised to solve the problems of the prior art as described above, and unlike the conventional solid-phase method or spray pyrolysis method, after preparing the phosphor raw material by coprecipitation method, the obtained phosphor raw material is put into a high pressure reactor and pyrolyzed. When the present invention was confirmed that it was possible to produce a phosphor having excellent crystallinity and luminescence properties in a spherical uniform form and completed the present invention.

An object of the present invention is to provide a phosphor having a spherical uniform form by a series of processes such as a coprecipitation process, a pyrolysis process and a heat treatment process by a liquid phase reaction.

1 is an electron micrograph of a phosphor prepared according to one specific embodiment of the present invention.

2 is a graph showing the change in emission intensity according to the change in the content of europium in the phosphor according to the present invention.

3 is a graph showing the change in color purity according to the content of europium in the phosphor according to the present invention.

The spherical red light-emitting phosphor according to the present invention is Y (NO ₃ ) ₃ to have a composition of europium activated yttrium borate red phosphor (Y _1-x BO ₃ : Eu _x ), where x is 0.01 to 0.2 g atom / mole. Water-soluble yttrium salts, such as Y ₂ (SO ₄ ) ₃ , YCl ₃ , boron compounds such as ammonium borate, potassium borate, sodium borate, lithium borate, and Eu (NO ₃ ) ₃ , Eu ₂ (SO ₄ ) ₃ , EuCl ₃ The winyohydrate obtained by mixing each of the phosphor raw materials selected from the group consisting of water-soluble europium salts, dissolved in water with stirring, was thermally decomposed in a high pressure reactor at 150 to 250 ° C. for 6 to 48 hours, and then neutralized. It is made by sintering at 800 to 1100 ° C. for 1 to 6 hours in an atmosphere or a reducing component atmosphere.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The spherical red light-emitting phosphor according to the present invention is Y (NO ₃ ) ₃ to have a composition of europium activated yttrium borate red phosphor (Y _1-x BO ₃ : Eu _x ), where x is 0.01 to 0.2 g atom / mole. Water-soluble yttrium salts, such as Y ₂ (SO ₄ ) ₃ , YCl ₃ , boron compounds such as ammonium borate, potassium borate, sodium borate, lithium borate, and Eu (NO ₃ ) ₃ , Eu ₂ (SO ₄ ) ₃ , EuCl ₃ The raw material hydrate obtained by mixing each of the phosphor raw materials selected from the group consisting of water-soluble europium salts, dissolved in water with stirring, was thermally decomposed in a high pressure reactor at 150 to 250 ° C. for 6 to 48 hours, and then neutralized. It is made by sintering for 1 to 6 hours at 800 to 1100 ℃ in the atmosphere or reducing component atmosphere.

According to the present invention, the raw materials of the phosphor are prepared by dissolving each of the raw materials of the phosphor in water to make an aqueous solution, and then mixing and stirring each of the aqueous solutions to sufficiently react to prepare raw material hydrates by coprecipitation. It is characterized by pyrolysis using a high pressure reactor or the like and sintering to produce a crystalline phosphor composition. At this time, each of the phosphor raw materials are composed of a host and an activator included as a doping material in the parent, and they use salts of metals that are well dissolved in water, that is, sulfates, nitrates, and halides of metals. As the mother, a water-soluble salt of yttrium and a boron compound are used, and an active salt of europium is used as an active agent.

The phosphor raw material may be selected from the group consisting of water-soluble yttrium salts, boron compounds, and water-soluble europium salts, and spherical phosphors may be obtained by reacting and coprecipitation once made into an aqueous solution.

Subsequently, the aqueous solutions of each of the phosphor raw materials, i.e., an aqueous yttrium salt solution, an aqueous boron compound solution and an europium salt aqueous solution, are mixed with agitation at room temperature or in a heated state, and co-precipitated to obtain an amorphous, hydrated raw material hydrate. To obtain. The raw material hydrate obtained above is subsequently pyrolyzed at 150 to 250 ° C. for 6 to 48 hours in a high pressure reactor to be converted into spherical particles. If the pyrolysis proceeds at a temperature of less than 150 ℃, there may be a problem that the sufficient dehydration and crystallization is not made, if the temperature exceeds 250 ℃, there may be a safety problem due to high vapor pressure.

By this pyrolysis, water is separated from the raw material hydrate in the amorphous state and in a hydrate state, and oxides are converted into particles through crystallization in which rearrangements are regularly rearranged to produce spherical phosphors. In addition, the product obtained by the pyrolysis may be crystallized and activated by sintering at 200 to 1100 ° C. for 1 to 6 hours in a heavy or reducing atmosphere. Particles of the phosphor obtained by the thermal decomposition are filled in a heat resistant container such as an alumina crucible, a quartz crucible, or the like and then sintered. The sintering time may vary depending on the amount of phosphor filled in the heat resistant container, the sintering temperature, etc., but may be crystallized and activated by sintering at 800 to 1100 ° C. for 1 to 6 hours, preferably 2 to 4 hours. If the sintering temperature is less than 800 ℃ excessive time is required for the sintering, and there may be a problem that the crystal growth is not sufficiently made, on the contrary, exceeding 1100 ℃ is not significant regardless of the growth of the crystal .

By sintering as described above, the particle size of the phosphor can be grown, and crystallization and activation can be completed.

The sintered product obtained after sintering is excited by ultraviolet rays, electron beams, vacuum ultraviolet rays or the like, and is a europium-activated yttrium borate phosphor (Y _1-x Bo ₃ : Eu _x ) exhibiting high luminance of red light emission (where x is 0.01 to 0.2 g atom / mole) )to be.

Hereinafter, preferred embodiments and comparative examples of the present invention will be described.

The following examples are intended to illustrate the invention and should not be understood as limiting the scope of the invention.

Example 1

Y _1-x BO ₃ Eu _x (where x is from 0.01 to 0.2 g atoms / mole) 4.2577 g of yttrium nitrate (Y (NO ₃ ) ₃ ), boric acid (H ₃ BO ₃ ) 0.6943 g such that x is 0.01 0.0481 g of europium nitrate (Eu (NO ₃ ) ₃ ) was weighed, dissolved in 250 ml of water to form an aqueous solution, and then mixed at 40 ° C. while stirring at a speed of about 300 rpm using a normal mechanical stirrer. The resulting precipitate was separated, placed in a high pressure reactor and pyrolyzed at a temperature of 200 ° C. for 48 hours to be converted into spherical phosphor particles, and the obtained phosphor particles were charged in an alumina crucible and 1100 ° C. under a nitrogen atmosphere containing a small amount of hydrogen. Sintering was carried out at a temperature of 2 hours to obtain a phosphor composition.

Scanning electron micrographs of the obtained phosphors are shown in FIG. 1. In addition, a graph of light emission characteristics according to the content of europium, which is an activator under ultraviolet (wavelength 147 nm) excitation, is shown in FIG. 2, and a graph of color purity is shown in FIG. 3. In addition, the color coordinates are shown in Table 1 below.

Example 2

Y _1-x BO ₃ : 4.0692 g of yttrium nitrate (Y (NO ₃ ) ₃ ), boric acid (H ₃ BO ₃ ) 0.6915 g, europium nitrate (Eu (NO ₃ ) ₃ ) 0.2393 g so that x is 0.05 in Eu _x Except for using the same as in Example 1 to obtain a phosphor composition.

The luminescence properties according to the content of europium, an activator under the obtained phosphor ultraviolet (wavelength 147 nm) excitation, are shown in FIG. 2, and a graph of color purity is shown in FIG. 3.

Example 3

Y _1-x BO ₃ : yttrium nitrate (Y (NO) ₃ ) ₃ ) 3.8357 g, boric acid (H ₃ BO ₃ ) 0.6880 g, europium nitrate (Eu (NO ₃ ) ₃ ) 0.4763 so that x is 0.1 in Eu _x Except for using g was carried out in the same manner as in Example 1 to obtain a phosphor composition.

The luminescence properties according to the content of europium, an activator under the obtained phosphor ultraviolet (wavelength 147 nm) excitation, are shown in FIG. 2, and a graph of color purity is shown in FIG. 3.

Example 4

Y _1-x BO ₃ : yttrium nitrate (Y (NO ₃ ) ₃ ) 3.6045 g, boric acid (H ₃ BO ₃ ) 0.6846 g, europium nitrate (Eu (NO ₃ ) ₃ ) 0.7109 g so that x is 0.15 in Eu _x Except for using the same as in Example 1 to obtain a phosphor composition.

The luminescence properties according to the content of europium, an activator under the obtained phosphor ultraviolet (wavelength 147 nm) excitation, are shown in FIG. 2, and a graph of color purity is shown in FIG. 3.

Example 5

Y _1-x BO ₃ : 3.3757 g of yttrium nitrate (Y (NO ₃ ) ₃ ), boric acid (H ₃ BO ₃ ) 0.6812 g, europium nitrate (Eu (NO ₃ ) ₃ ) 0.9431 g so that x is 0.2 in Eu _x Except for using the same as in Example 1 to obtain a phosphor composition.

The luminescence properties according to the content of europium, an activator under the obtained phosphor ultraviolet (wavelength 147 nm) excitation, are shown in FIG. 2, and a graph of color purity is shown in FIG. 3.

Therefore, according to the present invention, it is effective to provide spherical uniform phosphor particles using a high pressure reactor, and has been found to have sufficient light emission characteristics even at a lower temperature and a shorter post-treatment time than the phosphors prepared by other methods. Has the effect of providing.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications are within the scope of the appended claims.

Claims (1)

Y (NO ₃ ) ₃ , Y ₂ (SO ₄ ) ₃ , YCl ₃ to have a composition of europium activated yttrium borate red phosphor (Y _1-x BO ₃ : Eu _x ), where x is from 0.01 to 0.2 g atoms / mole Water soluble yttrium salt such as ammonium borate, potassium borate, sodium borate, lithium borate and the like, and a group consisting of water soluble europium salts such as Eu (NO ₃ ) ₃ ), Eu ₂ (SO ₄ ) ₃ and EuCl ₃ The raw material hydrate obtained by mixing the selected raw material solutions dissolved in water with stirring was thermally decomposed in a high pressure reactor at 150 to 250 ° C. for 6 to 48 hours, and then at 800 to 1100 ° C. in a medium or reducing atmosphere. Spherical red light emitting phosphor, characterized in that made by sintering for 1 to 6 hours.