KR100376276B1 - Process for green phosphor particles with spherical shape - Google Patents

Abstract

The present invention relates to a method for preparing spherical green phosphor powder, and more particularly, to preparing zinc silicide-based green phosphor using spray pyrolysis, optimizing zinc and silicate precursor materials constituting a parent and manganese precursor materials as activators. Formulated as a precursor solution, which is suitable for use in plasma displays and lamps which are sprayed into fine droplets using a droplet generator and dried and pyrolyzed in the gas phase to form one spherical phosphor powder from one droplet. It relates to a method for producing a green light emitting phosphor powder. In particular, the present invention has a zinc silicate-based green light emission represented by the following Chemical Formula 1, which has a spherical shape filled inside by combining starting precursor materials constituting the reaction solution in a general spray pyrolysis process, and thus exhibits optimal morphology and luminescence properties. It is a technology for producing phosphors.

Zn _2-X SiO ₄ : Mn _X

In Chemical Formula 1, 0.011 <x <0.13.

Description

Process for manufacturing spherical green phosphor powder

The present invention relates to a method for preparing spherical green phosphor powder, and more particularly, to preparing zinc silicide-based green phosphor using spray pyrolysis, optimizing zinc and silicate precursor materials constituting a parent and manganese precursor materials as activators. Formulated as a precursor solution, which is suitable for use in plasma displays and lamps which are sprayed into fine droplets using a droplet generator and dried and pyrolyzed in the gas phase to form one spherical phosphor powder from one droplet. It relates to a method for producing a green light emitting phosphor powder. In particular, the present invention has a zinc silicate-based green light emission represented by the following Chemical Formula 1, which has a spherical shape filled inside by combining starting precursor materials constituting the reaction solution in a general spray pyrolysis process, and thus exhibits optimal morphology and luminescence properties. It is a technology for producing phosphors.

Formula 1

Zn _2-X SiO ₄ : _X Mn

In Chemical Formula 1, 0.011 <x <0.13.

Recently, as interest in high definition television (HDTV) has increased, the development of displays has been active. Representative displays are plasma displays (PDP) and field emission displays (FED), which are recently popular flat panel displays. Unlike conventional displays, due to their lightness and thinness, these displays have many applications, such as wall-mounted TVs, computers, camcorders, and auto navigation devices.

Currently, powders that are used as phosphors for displays and lamps are mostly manufactured by a solid phase method through a long heat treatment process and a repeated milling process at a high temperature. Phosphor powders produced by the solid phase method are affected by the shape and the particle size distribution obtained according to the material. That is, in the solid phase method, it is difficult to control the shape and size of the phosphor powders. On the other hand, newly developed flat panel displays require superior properties than phosphor powders that are conventionally used in cathode ray tubes and lamps. In particular, the shape and size of the powder is recognized as a very important variable as well as the luminance of the phosphor. In general, it is reported that the phosphor powder has a spherical shape and has a size of 1 to 5 microns to show good characteristics. Phosphor powders having these requirements are difficult to manufacture in the existing phosphor manufacturing processes, and thus, gas phase processes such as spray pyrolysis and liquid phase methods such as sol-gel have been studied as alternatives.

Recently, the spray pyrolysis method has been actively studied as a process for producing spherical phosphor powders. However, in general, phosphor powders have a small specific surface area and have low surface defects to exhibit good luminescence properties, whereas phosphor powders produced by spray pyrolysis are known to be a problem because they have a hollow and porous form. have.

As a method for eliminating the disadvantages of the spray pyrolysis method, a technique has been developed to improve the characteristics of the phosphor powder by applying a colloidal solution to obtain a solid phosphor powder or by applying a flux to remove surface defects.

Since the spray pyrolysis is a gas phase process in which droplets are obtained from one droplet through drying and pyrolysis in a high temperature electric furnace, the properties of the starting precursor material have a great influence on the properties of the powders produced. That is, various variables such as solubility, decomposition rate, drying properties, crystallization properties of the precursor material affect the properties of the powders obtained. However, it is not yet clear how the properties of these precursor materials affect the properties of the powder obtained, and although some studies have been made, they have been limited to specific precursor materials. In other words, there is no study on how the properties of the precursor materials in the three-component or more multicomponent system such as the oxide-based phosphor affect the properties of the powder obtained by spray pyrolysis.

Accordingly, the present inventors have attempted to develop a process for preparing a Zn ₂ SiO ₄ : Mn phosphor represented by Chemical Formula 1, which is of great importance as a green phosphor by spray pyrolysis, and in particular by optimizing a combination of precursor materials to be used. The research efforts were made to raise the characteristics one step higher than the existing products. As a result, it is a precursor material of zinc and silicic acid constituting the parent and manganese, which is an activator material, which easily dissolves in a solvent such as water or alcohol, acetate, nitrate, chloride and hydrate. ) And the sulfide to find the optimal precursor composition through the combination with each other, thereby controlling the morphology and luminescence properties of the phosphor powders to complete the present invention. In particular, it was possible to optimize the light emission characteristics of the Zn ₂ SiO ₄ : Mn phosphor powder by improving the distribution of manganese in the mother by changing the precursor materials of the small amount of manganese doped in the mother.

Therefore, the main object of the present invention is to use the spray pyrolysis method, but through the optimized combination of the precursor materials of the parent and the activator to be used, the interior is filled in the form of a sphere and represented by the formula (1) showing the optimal green light emission characteristics It is to provide a method for producing a zinc silicate-based (Zn ₂ SiO ₄ : Mn) green phosphor powder.

In addition, another object of the present invention is to provide a zinc silicide-based (Zn ₂ SiO ₄ : Mn) green phosphor represented by Chemical Formula 1 prepared by the above method.

1 shows the light emission characteristics of Examples 3 and 4 and Comparative Example 1 (commercially available) as Zn ₂ SiO ₄ : Mn phosphor powders prepared by spray pyrolysis according to the present invention.

FIG. 2 is an electron micrograph of Zn ₂ SiO ₄ : Mn phosphor powder (Example 4) obtained by using manganese sulfide as a precursor material of manganese in spray pyrolysis.

FIG. 3 is an electron micrograph of Zn ₂ SiO ₄ : Mn phosphor powder (Example 5) obtained by using zinc acetate as a precursor material of zinc in spray pyrolysis.

FIG. 4 is an electron micrograph of Zn ₂ SiO ₄ : Mn phosphor powder (Example 6) obtained using zinc nitrate as a precursor material of zinc in spray pyrolysis.

The present invention

1) Distilled water and alcohol to which a trace amount of nitric acid was added using 105-125% of the zinc precursor material and tetraethyl allosilicate (TEOS) selected from zinc nitrate, zinc acetate, and zinc chloride as a parent to a phosphor as a stoichiometric ratio to zinc. The active material which is doped with the silicic acid precursor material selected from nanometer-sized SiO ₂ powder prepared by gas phase or liquid phase method, and dissolved in manganese sulfide and manganese chloride in distilled water. Preparing a precursor solution of a phosphor having a size of 0.02 to 3 M;

2) injecting the precursor solution into a spray device to generate droplets of 0.1 to 100 ㎛ diameter; And

3) The method of preparing a spherical zinc silicic acid-based green phosphor powder represented by the following formula (1) comprising the step of introducing the droplet into a high temperature tubular reactor (200 to 1,500 ° C.).

Formula 1

Zn _2-X SiO ₄ : _X Mn

In Chemical Formula 1, 0.011 <x <0.13.

In addition, the present invention comprises a spherical zinc silicate-based green phosphor powder represented by the formula (1) prepared by the above method.

The present invention will be described in more detail as follows.

The present invention uses a spray pyrolysis method to prepare the zinc silicate-based green phosphor powder represented by the formula (1), spherical by the optimal composition by changing the composition of the zinc and silicic acid precursor material constituting the parent and the manganese precursor material activator The present invention relates to a method for manufacturing a zinc silicate-based green light-emitting phosphor which is filled inside and excellent in light emission characteristics.

Hereinafter, a method of preparing the green phosphor represented by Chemical Formula 1 obtained by an optimized combination of precursor materials according to the present invention will be described in more detail by dividing each process based on spray pyrolysis.

1) 1st process: manufacturing process of precursor solution of fluorescent substance particle

The present invention performs a process for preparing a precursor material by dissolving zinc and manganese metals and silicic acid (silicon) raw material in distilled water or alcohol for the combination of precursor materials.

Precursor materials of the metals of zinc and manganese constituting the matrix of the phosphor powder are selected from acetates, nitrates, chlorides, hydrates and sulfides that are easily dissolved in a solvent such as water or alcohol. Can be derived. That is, the zinc precursor material is selected from zinc nitrate, zinc acetate and zinc chloride, preferably using acetate and nitrate, and as the active material doping the mother manganese precursor material as manganese sulfide, manganese chloride, manganese One selected from acetate and manganese nitrate is used, preferably sulfide and chloride. As a precursor material of silicic acid, tetraethyl allosilicate, which is capable of producing a uniform solution, is preferable, but because of its high price, nano-sized silica (SiO ₂ ) powders prepared by vapor phase or liquid phase can be dispersed in a solution and used as a substitute. have.

In preparing the Zn ₂ SiO ₄ : Mn phosphor powder represented by Chemical Formula 1 of the present invention, since a stable salt does not exist for the essential silicon component, alkoxides that easily hydrate are used as silicon raw materials. That is, the silicon alkoxide materials are dispersed in water or a solvent, and used to obtain a stable solution through hydration and dissociation. In the present invention, tetraethyl orthosilicate (TEOS) is used as a silicon component, and a fixed amount is added to distilled water and nitric acid is added as a catalyst to make a transparent and clean solution, which is used as a spray solution. As described above, a substance other than TEOS may be used as the silicone component. At this time, since TEOS used in the present invention has a property of being easily volatilized, part of the TEOS is volatilized and disappears into the gas phase during the spray pyrolysis reaction. As a result, when prepared by adding 2/1, the stoichiometric ratio of Zn / Si, the Si component is insufficient and ZnO is present inside the particles, and this material significantly lowers the emission luminance of the Zn ₂ SiO ₄ : Mn phosphor powder. Thrown away. In addition, in the case where ZnO remains inside the particles, agglomeration between the particles occurs in a high temperature heat treatment process and the spherical shape disappears, so it is very important to find the optimal amount of TEOS.

Therefore, in the present invention, the TEOS is dissolved in 105 to 125% in a stoichiometric ratio to zinc in distilled water and alcohol to which a small amount of nitric acid is added.

In addition, since the size of the phosphor particles to be produced is determined according to the concentration of the precursor solution, the concentration of the precursor solution should be appropriate to produce particles of a desired size, and the total concentration of the precursor solution is preferably in the range of 0.02 to 3.0M. . If the total concentration of the precursor does not reach 0.02M, the amount of phosphor particles produced is too small, and if the total concentration of the precursor exceeds 3.0M, it is difficult to dissolve substances forming the precursor solution in distilled water. .

In addition, the concentration of manganese, an activator for doping the phosphor matrix, is used in the range of 0.011 to 0.13 mol%, and if the concentration is less than the above range, the emission luminance also decreases and the afterglow time is long. Is short, but there is a problem that the light emission luminance is inferior.

2) second process: spraying of droplets

The next process is to spray each precursor solution prepared in the process into a droplet using a spray device.

As a spray device for spraying droplets in the present invention, an ultrasonic atomizer, an air nozzle sprayer, an ultrasonic nozzle sprayer, a filter expansion aerosol generator (FEAG), or the like may be used. Here, the ultrasonic and FEAG spray apparatus can be produced in the sub-micron size of the fine phosphor powder at a high concentration, the air nozzle and the ultrasonic nozzle to enable the production of submicron-sized particles in a large amount in the micron.

In addition, the sprayed droplets have a diameter of 0.1 to 100 μm, and if the diameter of the droplets is less than 0.1 μm, there is a problem that the size of the resulting particles is too small, and if the diameter of the droplets exceeds 100 μm, The problem arises that the size of the particles produced is too large.

3) third process: generation of spherical phosphor particles

The present invention performs the process of converting the droplets generated in the above process into precursors of the phosphor particles in a high temperature tubular reactor.

The inside of the tubular reactor is maintained at a high temperature by an electric furnace, the temperature of the electric furnace is preferably 200 to 1,500 ℃ for drying the precursor materials. However, since the Zn ₂ SiO ₄ : Mn phosphor powder is a material obtained by the reaction of several hours or more at a high temperature of more than 1,200 ℃ in a general solid phase method, the desired crystal phase is not obtained in the spray pyrolysis process having a residence time of several seconds.

Therefore, precursor materials obtained by spray pyrolysis require post-treatment for crystal growth, and the present invention further includes a step of post-treating the precursor materials at 800 to 1,350 ° C. for 1 to 5 hours. As the post-treatment process, both direct oxidation heat treatment processes may be used, or both methods of first undergoing heat treatment in an oxidizing atmosphere and then undergoing an oxidation / reduction heat treatment process of re-heat treatment in a reducing atmosphere may be used.

First, when only the direct oxidation heat treatment process is performed, the precursor particles obtained by the spray pyrolysis method are heat-treated in an air atmosphere for at least 1 hour at a high temperature of 800 ° C. or higher. In this case, in the case of the oxidizing heat treatment process, the characteristics of the phosphor powders obtained are largely dependent on the type of starting precursor material used. For example, in the case of using manganese sulfide as a precursor material of manganese, which is an activator material, dispersibility in the matrix of the manganese compound is good, and sulfur contained in the precursor material acts as a reducing agent and has good luminescence properties even if it undergoes direct oxidation. Zn ₂ SiO ₄ : Mn phosphor powders are obtained. That is, since a complex reduction treatment process using hydrogen mixed gas is not necessary, there is an advantage of greatly reducing equipment costs, production time, and production cost.

In the case of the oxidation / reduction process, the heat treatment process is performed for 1 hour or more at a temperature of 800 ° C. or more, and then the reduction process is performed using a mixed gas of hydrogen and nitrogen at a temperature of 800 ° C. or more. That is, the reduction treatment is heat-treated for 30 minutes to 5 hours at a temperature range of 700 to 1,000 ℃ in a hydrogen / nitrogen mixed gas atmosphere of 2 to 10%.

By the above method, for the Zn ₂ SiO ₄ : Mn green phosphor powders represented by the formula (1) obtained by changing the precursor materials, vacuum ultraviolet (VUV) for the application characteristics to the plasma display As a result of comparing and analyzing the light emission characteristics in the () area, it can be applied to a plasma display that requires a phosphor having a high brightness by showing a high emission intensity of 135% compared to the commercial product.

Hereinafter, the present invention will be described in more detail with reference to the following Examples, these examples are only for illustrating the present invention more specifically, the scope of the present invention in accordance with the gist of the present invention to these Examples It will be apparent to those skilled in the art that the present invention is not limited thereto.

Examples 1-4: Influence of Manganese Precursor Material Changes as Active Agents

Zinc acetate and TEOS are used as starting materials of zinc and silicon constituting the parent, and manganese nitrate (Example 1), manganese acetate (Example 2), and manganese chloride (Example 3) are used as precursor materials of manganese, which are active materials. ) And manganese sulfide (Example 4) were used to bring the total concentration of the precursor solution to 0.9 molarity. TEOS, a raw material of the silicon component, was added in an amount of 17% more than 2/1 of the stoichiometric ratio of Zn / Si.

In addition, an ultrasonic atomizer was used as a device for generating droplets. The production temperature of the spray pyrolysis method was 1,000 ℃, Zn ₂ SiO ₄ : Mn phosphors were synthesized through the post-heat treatment process of direct oxidation and oxidation / reduction of the obtained precursor powders. In the case of the direct oxidation heat treatment process, the heat treatment was performed for 3 hours while changing the heat treatment temperature from 800 ° C. to 1350 ° C. in 25 ° C. units. Oxidation / reduction In the two-step heat treatment process, the heat treatment process was first performed at a high temperature in an oxidizing atmosphere for 3 hours, followed by reduction treatment while flowing 5% hydrogen / nitrogen mixed gas at 100 ml / min for 2 hours at 850 ° C.

In the case of Examples 1 (manganese nitrate), Example 2 (manganese acetate) and Example 3 (manganese chloride) for changing the active agent, +2 ions in which manganese emits green light when subjected to oxidation There was no complete reduction to, resulting in insufficient light emission luminance. On the other hand, in the case of using manganese sulfide as an activator of Example 4, the manganese is sufficiently reduced by only the oxidation process, thereby exhibiting good luminescence brightness even without undergoing a reduction heat treatment process.

The emission intensity when only the oxidative heat treatment process was performed was performed in the order of sulfide>chloride>acetate> nitrate depending on the precursor of manganese. The luminescence intensity of the Zn ₂ SiO ₄ : Mn phosphor powders obtained when the oxidation heat treatment temperature was 1,150 ° C. had a luminescence intensity of 125% of that of Example 4 (manganese sulfide), compared to the commercial product prepared by the solid phase method. And Example 1 (manganese nitrate), Example 2 (manganese acetate), and Example 3 (manganese chloride) showed the luminescence intensity of 76%, 82%, 108%. In other words, the use of manganese sulfide or chloride as an activator shows that it is possible to produce Zn ₂ SiO ₄ : Mn phosphor powders having better luminescence intensity than commercial products even without a complicated reduction process. On the other hand, when manganese acetate and nitrate were used as the activator, the luminescent intensity was worse than that of the commercial product after the oxidative heat treatment.

In particular, in the case of Example 4 (manganese sulfide), the present invention found a temperature having an optimal emission intensity while varying the oxidation heat treatment temperature. When the heat treatment time for 3 hours was passed, the optimum heat treatment temperature was 1,150 ℃, the emission intensity at this time was 125% of the upper article. At temperatures below 1,150 ° C, the luminescence intensity increased as the heat treatment temperature increased, and at 1050 ° C, the luminescence intensity corresponded to 86% of the upper items. On the other hand, the light emission intensity did not change much with the increase of the temperature at 1,150 ° C. or higher, and the light emission intensity was 121% of the upper product at 1,250 ° C. That is, even without the reduction treatment, crystallization of Zn ₂ SiO ₄ , activation into the matrix of manganese, and reduction of manganese +2 transverse occurred completely during the heat treatment process at 1,150 ° C. for 3 hours.

Even after the reduction treatment, the type of manganese precursor material significantly influenced the emission intensity of the Zn ₂ SiO ₄ : Mn phosphor powders. In the case of using the manganese sulfide of Example 4, since the manganese was sufficiently reduced to +2 valence in the oxidation treatment process at a temperature of 1,150 ° C or higher, the increase in luminance did not appear even after the reduction treatment process. On the other hand, when the manganese chloride, acetate, and nitrate were used, the particles obtained by the reduction treatment after the oxidative heat treatment increased rapidly. When the manganese chloride of Example 3 was used, the obtained particles showed luminescence intensity corresponding to 108% of the commercial product after the oxidation treatment at 1,150 ° C., but the Zn ₂ SiO ₄ : Mn phosphor powder was subjected to a reduction process using a hydrogen gas mixture. Showed luminescence intensity of 135% of the commercial item. This emission intensity can be further increased by optimizing the oxidation treatment temperature or the reduction treatment temperature. In the case of using manganese acetate (Example 2) or manganese nitrate (Example 1), since the manganese was not sufficiently reduced in the oxidative heat treatment step, the luminescence intensity rapidly increased after the reduction heat treatment step. In the case of using the manganese acetate of Example 2, the powder subjected to the reduction treatment had a 56% increase in luminescence brightness than the powders subjected only to the oxidative heat treatment process. That is, the powder subjected only to the oxidative heat treatment had the luminescence intensity of 80% of the commercial article, but after the reduction heat treatment process, the powder had the luminescence intensity of 125% of the commercial article. In the case of using the manganese nitrate of Example 1, the luminescence intensity increased 62% after the reduction heat treatment than after the oxidation heat treatment. That is, after the oxidative heat treatment, the luminescence intensity was 69% of the upper article, but after the reduction heat treatment, the luminescence intensity was 112% of the upper article. Therefore, manganese sulfide or chloride is suitable as a precursor material of manganese in terms of emission intensity of Zn ₂ SiO ₄ : Mn phosphor powders.

1 compares the light emission characteristics of Zn ₂ SiO ₄ : Mn phosphor powders prepared in the present invention and commercial powders. Commercially available powders are produced by the solid phase method. In the case of using manganese sulfide in spray pyrolysis (Example 4), the powder obtained was subjected to a direct oxidizing heat treatment step only at 1,150 ° C. and not subjected to a reduction heat treatment step. On the other hand, when manganese chloride was used, it was subjected to an oxidative heat treatment at 1,200 ° C. and a reduction treatment at 850 ° C. Zn ₂ SiO ₄ : Mn phosphor powders obtained using manganese sulfide and chloride have luminous intensity of 125% and 135%, respectively.

X-ray analysis of Zn ₂ SiO ₄ : Mn phosphor powders obtained after oxidation showed that pure silicate silicate crystals of pure Willemite structure were obtained when the oxidation treatment temperature was above 900 ℃, and the crystallinity was further increased above 1,000 ℃. Did not do it.

FIG. 2 is an electron micrograph of powders prepared by spray pyrolysis in the case of using sulfide as a manganese precursor material, subjected to oxidative heat treatment at 1,250 ° C. for 3 hours. Even at the high annealing temperature of 1,250 ℃, no agglomeration between the particles occurred and the perfect spherical shape was maintained. On the other hand, in the case of using manganese manganese nitrate (Example 1), manganese acetate (Example 2) and chloride (Example 3) as a manganese precursor, aggregation between the particles occurred at a heat treatment temperature of more than 1,200 ℃. That is, it can be seen that manganese sulfide is suitable in terms of the form of Zn ₂ SiO ₄ : Mn phosphor powder.

The whiteness of the obtained Zn ₂ SiO ₄ : Mn phosphor powders was also greatly influenced by the type of manganese precursor material. The whiteness of Zn ₂ SiO ₄ : Mn phosphor powders obtained when manganese sulfide was used was the best. That is, when manganese sulfide was used, the whiteness of the precursor powders obtained by spray pyrolysis was the best, and the whiteness was the best even after the oxidation treatment. On the other hand, in the case of using manganese nitrate or acetate, the powders were dark red after oxidation treatment, and perfect whiteness was not obtained even after reduction treatment. On the other hand, in the case of using manganese sulfide, Zn ₂ SiO ₄ : Mn phosphor powders had a pure white color even though they did not undergo a reduction process. The reason is that when manganese sulfide is used, the manganese components are well distributed evenly in the zinc silicate matrix, so that the reduction is easily performed, so that the Mn is completely reduced to +2 in the oxidation heat treatment process and the doping of manganese components in the matrix is completed. . On the other hand, when manganese nitrate or acetate is used, Zn ₂ SiO ₄ : Mn phosphor powders have a gray color because some coagulation between manganese components is not performed inside the mother, and thus perfect doping does not occur inside the mother. In the case of using manganese acetate or nitrate as the activator precursor, the emission intensity of Zn ₂ SiO ₄ : Mn phosphor powder is worse than that of manganese sulfide because the distribution of manganese in the parent is not uniform. In the case of using manganese chloride, the powders were partially grayish after the oxidation treatment, but a white powder was obtained after the reduction treatment. That is, it can be seen that manganese sulfide or chloride is suitable as a precursor material of manganese in terms of the whiteness of Zn ₂ SiO ₄ : Mn phosphor powders.

Examples 5-7: Influence of zinc precursor material constituting the parent

Zinc is a material constituting the zinc silicate matrix, and has a great influence on the morphology and luminescence properties of the Zn ₂ SiO ₄ : Mn phosphor powder prepared by spray pyrolysis. In the present invention, to improve the shape of the Zn ₂ SiO ₄ : Mn phosphor powder obtained by controlling the precursor material of zinc and to improve the luminance of light.

It was prepared in the same manner as in Example 1, but zinc acetate (Example 5), zinc nitrate (Example 6) and zinc chloride (Example 7) were used as precursor materials of zinc, respectively, which are relatively inexpensive. The powders obtained by spray pyrolysis were oxidized at 1,200 ° C. for 3 hours.

3 and 4 show electron micrographs of Zn ₂ SiO ₄ : Mn phosphor powders of Examples 5 and 6. In the case of Examples 5 and 6, which used acetate and nitrate as precursor materials of zinc, the obtained particles maintained a perfect spherical shape and no aggregation between the particles occurred. However, in Example 6 (zinc nitrate), the particles obtained had excellent surface properties. That is, the particles obtained through zinc nitrate had a smooth particle surface, while Example 5 (zinc acetate) had a partially distorted surface. On the other hand, in the case of Example 7 (zinc chloride), the spherical shape was also broken and a lot of aggregation between the particles occurred. The reason is that when zinc chloride is used, Zn / Si ratio is not maintained at 2/1 in the particles obtained due to the high volatility of chlorine chloride, and impurities other than zinc silicate are present in the particles and they are aggregated between particles. Caused. In other words, zinc acetate (Example 5) or zinc nitrate (Example 6) were more suitable than zinc chloride (Example 7) in terms of the form of Zn ₂ SiO ₄ : Mn phosphor powder.

The luminescence intensity of Zn ₂ SiO ₄ : Mn phosphor powders was also influenced by the kind of zinc precursor materials. The powders obtained when using the zinc acetate of Example 5 were higher in brightness than the powders obtained when using zinc nitrate or chloride. The luminescence intensity of Zn ₂ SiO ₄ : Mn phosphor powders obtained by oxidizing the powders obtained by using manganese sulfide as the active material at 1,100 ° C. for 3 hours was determined by using commercially available zinc acetate (Example 5). In comparison, 120% of zinc nitrate was used (Example 6). In the case where zinc chloride was used (Example 7), the Zn ₂ SiO ₄ : Mn phosphor was not obtained due to the volatilization of the zinc component under the same production conditions, and the emission was also very bad.

Example 8 Effect of Addition of TEOS

In Example 8, Example 2 (manganese acetate) and Example 4 (manganese sulfide), which were prepared in the same manner as in Example 1 but selected as a good starting material, were used as precursor materials for zinc and manganese, respectively. And TEOS was added in excess of 107% of the stoichiometric ratio.

When TEOS was added in excess of 107% in a stoichiometric ratio, pure Zn ₂ SiO ₄ : Mn phosphor powders of pure Willemite structure were obtained after oxidation treatment. In this composition, no agglomeration between the particles occurred and the spherical shape was maintained even after the heat treatment. On the other hand, when the addition amount of TEOS was added at 105% or less of the stoichiometric ratio, black particles were obtained after heat treatment, and light emission was also very bad. In other words, a pure Willemite structure Zn ₂ SiO ₄ : Mn phosphor powder was not obtained. When the addition amount of TEOS added 117% of the stoichiometric ratio, it showed the best luminescence intensity.

Example 9 Influence of Droplet Generator

It was prepared in the same manner as in Example 1 except that an air nozzle was used as a droplet generating apparatus to produce a large amount of Zn ₂ SiO ₄ : Mn phosphor powders.

The results obtained when using an air nozzle as the droplet generator were consistent with those in the above examples. That is, the powders obtained when manganese sulfide or chloride was used as the precursor of manganese as an activator showed good characteristics in brightness, whiteness, and the like. The properties of the powders prepared also maintained the spherical shape as in the above examples and no aggregation between the particles occurred. On the other hand, in the case of using the air nozzle, the powders obtained were larger than in the case of using ultrasonic waves because of the large droplet size. In the case of using an ultrasonic atomizer, powders of about 1 micron in size were obtained according to the concentration of the solution, whereas in the case of using an air nozzle, powders of 1 to 5 microns were prepared according to the concentration of the solution. That is, an ultrasonic atomizer is suitable for ultrafine particles of 1 micron size, and an air nozzle is suitable for producing larger particles.

In addition, in the case of using the ultrasonic droplet generator, when silica powder is used as a raw material of silicic acid, it is difficult to synthesize a pure powder due to the phase separation problem, but in the case of using an air nozzle, the reaction colloidal solution is continued before injecting the nozzle into the nozzle. Due to the stirring, there was no phase separation problem, and thus, the synthesis of the phosphor powder having a uniform composition was possible. Therefore, when silica powder is used as a raw material of silicic acid, it is possible to synthesize phosphor powder with low efficiency at low raw material cost.

In addition to the embodiments shown above, in the spray pyrolysis, the luminescence properties of the phosphor powders obtained are influenced by various variables such as the concentration of the solution used, the doping concentration, the preparation temperature, and the heat treatment temperature.

Accordingly, although Zn ₂ SiO ₄ : Mn phosphor powders having luminescence brightness corresponding to 135% of the commercial products are prepared in the present invention, it is possible to prepare powders having more luminance and these detailed parameters are not shown in the present invention. It reminds me once again to enter the invention.

As described and demonstrated in detail above, in the present invention, by optimizing the precursor materials used in the preparation of the green light emitting phosphor Zn ₂ SiO ₄ : Mn phosphor powders by spray pyrolysis, the luminescent properties of the powders obtained are greatly improved.

In other words, by optimizing the precursor materials of manganese and zinc and silicic acid that are used in trace amounts as activators, the luminescence intensity, form, and whiteness of Zn ₂ SiO ₄ : Mn phosphor powders are significantly improved compared to commercial products. I was. In addition, by using a precursor material of manganese, an active agent, as a sulfide, Zn ₂ SiO ₄ : Mn phosphor powders having high brightness, spherical shape, and high whiteness can be prepared without a complicated reduction process. The development of such suitable precursors does not require a reduction process, which simplifies the manufacturing process and saves manufacturing cost, time, and equipment cost, thus making breakthrough electricity for commercial production of Zn ₂ SiO ₄ : Mn phosphor powders by spray pyrolysis. Can be. In addition, the Zn ₂ SiO ₄ : Mn phosphor powders obtained by using manganese chloride or sulfide show a high emission intensity of about 135% compared to commercial products, and thus will be very appropriately used in displays requiring a high luminance phosphor. In addition, in the present invention, since the shape of the Zn ₂ SiO ₄ : Mn phosphor powders prepared by optimizing the zinc and silicate precursor materials constituting the parent is adjusted to have a perfect spherical shape, it has very good characteristics in terms of brightness and shape. have.

Claims (7)

1) Distilled water and alcohol to which a trace amount of nitric acid was added using 105-125% of the zinc precursor material and tetraethyl allosilicate (TEOS) selected from zinc nitrate, zinc acetate, and zinc chloride as a parent to a phosphor as a stoichiometric ratio to zinc. The active material which is doped with the silicic acid precursor material selected from nanometer-sized SiO ₂ powder prepared by gas phase or liquid phase method, and dissolved in manganese sulfide and manganese chloride in distilled water. Preparing a precursor solution of a phosphor having a size of 0.02 to 3 M; 2) injecting the precursor solution into a spray device to generate droplets of 0.1 to 100 ㎛ diameter; And 3) A method for producing a spherical zinc silicate-based green phosphor powder represented by the following Chemical Formula 1, comprising the step of introducing the droplet into a high temperature tubular reactor (200-1,500 ° C.). Formula 1 Zn _2-X SiO ₄ : Mn _X In Chemical Formula 1, 0.011 <x <0.13. The method according to claim 1, further comprising a post-treatment step of subjecting the phosphor particles obtained after the step 3) to an oxidative heat treatment or an oxidation / reduction composite heat treatment for 1 to 5 hours at a temperature of 800 to 1,350 ° C. A method for producing a spherical zinc silicate-based green phosphor powder represented by the formula (1). According to claim 2, wherein the reduction process is a spherical formula represented by the formula (1) characterized in that the heat treatment for 30 minutes to 5 hours in a temperature range of 700 to 1,000 ℃ in a hydrogen / nitrogen mixed gas atmosphere of 2 to 10% Method for producing a zinc silicate-based green phosphor powder. delete The method of claim 1, wherein the spraying apparatus includes an ultrasonic wave, an air nozzle, an ultrasonic nozzle, and a filter expansion droplet generating device. The method of claim 1, wherein the concentration of manganese is added in a range of 0.011 to 0.13 mol%. Spherical zinc silicate-based green phosphor represented by the following formula (1), characterized in that prepared by the method of claim 1. Formula 1 Zn _2-X SiO ₄ : _X Mn In Chemical Formula 1, 0.011 <x <0.13.