Alkali-earth metal silicate based luminophores and method of improving long-term stability thereof. RU patent 2507233.
 Marking composition based on inorganic luminophors, method of metal products marking and metal product / 2493192Composition for marking of metal products produced by powder metallurgy method includes not more than 50% of wt % of luminophor and 50 wt % and more of binding-lubricating agent being fatty acid derivatives or powders of synthetic wax and/or paraffin. Marking of metal products by this composition consists in mixing of alloy metal powder with marking composition, which consists of at least one inorganic agent with property to provide luminescence at irradiation and binding-lubricating agent with subsequent pressing of obtained mixture and its sintering at temperature not exceeding 900°C. |
 Method of increasing stability of aqueous solution of quantum dots - cadmium selenide nanoparticles coated with mercapto acids / 2484116Aqueous solution of quantum dots based on cadmium selenide coated with mercapto acids is stabilised by adding sodium sulphite until achieving its concentration of 0.02-0.2 mol/l in the solution. |
 Polymer nanoparticles containing medium for photon up-conversion / 2479616Polymer nanoparticles contain a medium for photon up-conversion and a stabilising agent. Said medium contains a polymer matrix having two organic components distributed therein. The first component is capable of absorbing light at a first wavelength in the range w≤λ1≤x and acts as a sensitiser in said medium. The second component is capable of emitting light at a second wavelength in the range y≤λ2≤z, where λ2≤λ1, and acts as an emitting component in said medium. The stabilising agent is selected from hydrophilic or amphiphilic polymers. |
 Polymer luminescent composition for obtaining white light excited by blue light-emtting diode / 2405804Polymer luminescent composition for obtaining white light excited by a blue light-emitting diode contains the following components, pts. wt: transparent polymer 100; photoluminescent phosphor based on garnet Y3Al5O12:Ce or Gd3Al5O12:Ce, or based on a mixture of said compounds 1.5-5.0; polyethylene wax in form of powder with particle size of 18-30 mcm 0.1-0.7; stabiliser 0.2-1.0. The transparent polymer used can be polycarbonate, polystyrene or a copolymer of styrene with acrylonitrile and butadiene. The stabiliser can be a compound from a group of sterically hindered phosphites. |
 Method for synthesis of semiconductor quantum dots / 2381304Invention relates to synthesis of nucleus- and nucleus-shell type semiconductor quantum dots through colloidal synthesis, which can be used in making different luminescent materials, as well as a base for making subminiature light-emitting diodes, white light sources, single-electron transistors, non-linear optical devices, photodetector and photovoltaic devices. The method for synthesis of semiconductor quantum dots based on chalcogenides of group II or group IV metals involves synthesis of nuclei of nanocrystals from a precursor containing chalcogen, and a precursor containing group II or IV metals, using an organic solvent and a surface modifier in form of (aminoalkyl)trialkoxysilanes. The nuclei are synthesised at constant temperature within the limits of 150 - 250°C for 15 s to 1 hour and the reaction mixture containing the nucleus of nanocrystals is further treated with UV light for 1-10 minutes and ultrasound for 5-15 minutes. |
 Method of obtaining luminescent nanoparticles of cadmium sulphide, stabilised with polymer matrices / 2370517Method is described for obtaining luminescent nanoparticles of cadmium sulphide, stabilised with polymer matrices, involving growing nanoparticles of cadmium sulphide directly in polymer matrices. A polymer compound, chosen from a series which includes polystyrene-block-polyethylene oxide, polystyrene-block-polyethylene oxide, polystyrene-block-4-vinylpyridine or polyphenylene, is dissolved, anionic surfactant is added to the obtained mixture with subsequent addition of a compound which contains cadmium cations, and then a compound which contains sulphur anions, and after growing cadmium sulphide nanoparticles excess anionic surfactant is removed. |
 Method for applying protective film on surfaces of phosphor particles / 2256254Proposed method that can be used for encapsulating phosphor particles to enhance their lighting and servicing parameters by producing continuous silicon dioxide film on their surfaces includes treatment of phosphor particles with 0.5 and 4 mass percent sols of polysilicic acid synthesized by hydrolyses of tetraethoxysilane in 0.6 - 0.8 mass percent aqueous solution of ammonia. |
 Method of preparing moisture-resistant particles of electroluminescent phosphor / 2247761Nitride coating precursor, in particular aluminum-, gallium-, or tin-containing metalloorganic nitride, is charged into reaction vessel 10a filled with electroluminescent phosphor, e.g. ZuS-Cu, and surrounded by heating means 30a using nitrogen as inert gas carrier. Precursor is passed through pipeline 32 open all over its length. Co-reagent, e.g. anhydrous ammonia is fed into lower part of vessel 12a through porous glass disk 12a. When vessel 10a is heated to 150-225°C, nitride coating precipitates on phosphor particles being in fluidized state. Phosphor bearing nonoxide coating is characterized by high brightness after 100 h use at high humidity. |
| Method of preparing moisture-resistant particles of electroluminescent phosphor / 2247761 Nitride coating precursor, in particular aluminum-, gallium-, or tin-containing metalloorganic nitride, is charged into reaction vessel 10a filled with electroluminescent phosphor, e.g. ZuS-Cu, and surrounded by heating means 30a using nitrogen as inert gas carrier. Precursor is passed through pipeline 32 open all over its length. Co-reagent, e.g. anhydrous ammonia is fed into lower part of vessel 12a through porous glass disk 12a. When vessel 10a is heated to 150-225°C, nitride coating precipitates on phosphor particles being in fluidized state. Phosphor bearing nonoxide coating is characterized by high brightness after 100 h use at high humidity. |
| Method for applying protective film on surfaces of phosphor particles / 2256254 Proposed method that can be used for encapsulating phosphor particles to enhance their lighting and servicing parameters by producing continuous silicon dioxide film on their surfaces includes treatment of phosphor particles with 0.5 and 4 mass percent sols of polysilicic acid synthesized by hydrolyses of tetraethoxysilane in 0.6 - 0.8 mass percent aqueous solution of ammonia. |
| Method of obtaining luminescent nanoparticles of cadmium sulphide, stabilised with polymer matrices / 2370517 Method is described for obtaining luminescent nanoparticles of cadmium sulphide, stabilised with polymer matrices, involving growing nanoparticles of cadmium sulphide directly in polymer matrices. A polymer compound, chosen from a series which includes polystyrene-block-polyethylene oxide, polystyrene-block-polyethylene oxide, polystyrene-block-4-vinylpyridine or polyphenylene, is dissolved, anionic surfactant is added to the obtained mixture with subsequent addition of a compound which contains cadmium cations, and then a compound which contains sulphur anions, and after growing cadmium sulphide nanoparticles excess anionic surfactant is removed. |
| Method for synthesis of semiconductor quantum dots / 2381304 Invention relates to synthesis of nucleus- and nucleus-shell type semiconductor quantum dots through colloidal synthesis, which can be used in making different luminescent materials, as well as a base for making subminiature light-emitting diodes, white light sources, single-electron transistors, non-linear optical devices, photodetector and photovoltaic devices. The method for synthesis of semiconductor quantum dots based on chalcogenides of group II or group IV metals involves synthesis of nuclei of nanocrystals from a precursor containing chalcogen, and a precursor containing group II or IV metals, using an organic solvent and a surface modifier in form of (aminoalkyl)trialkoxysilanes. The nuclei are synthesised at constant temperature within the limits of 150 - 250°C for 15 s to 1 hour and the reaction mixture containing the nucleus of nanocrystals is further treated with UV light for 1-10 minutes and ultrasound for 5-15 minutes. |
| Polymer luminescent composition for obtaining white light excited by blue light-emtting diode / 2405804 Polymer luminescent composition for obtaining white light excited by a blue light-emitting diode contains the following components, pts. wt: transparent polymer 100; photoluminescent phosphor based on garnet Y3Al5O12:Ce or Gd3Al5O12:Ce, or based on a mixture of said compounds 1.5-5.0; polyethylene wax in form of powder with particle size of 18-30 mcm 0.1-0.7; stabiliser 0.2-1.0. The transparent polymer used can be polycarbonate, polystyrene or a copolymer of styrene with acrylonitrile and butadiene. The stabiliser can be a compound from a group of sterically hindered phosphites. |
| Polymer nanoparticles containing medium for photon up-conversion / 2479616 Polymer nanoparticles contain a medium for photon up-conversion and a stabilising agent. Said medium contains a polymer matrix having two organic components distributed therein. The first component is capable of absorbing light at a first wavelength in the range w≤λ1≤x and acts as a sensitiser in said medium. The second component is capable of emitting light at a second wavelength in the range y≤λ2≤z, where λ2≤λ1, and acts as an emitting component in said medium. The stabilising agent is selected from hydrophilic or amphiphilic polymers. |
| Method of increasing stability of aqueous solution of quantum dots - cadmium selenide nanoparticles coated with mercapto acids / 2484116 Aqueous solution of quantum dots based on cadmium selenide coated with mercapto acids is stabilised by adding sodium sulphite until achieving its concentration of 0.02-0.2 mol/l in the solution. |
| Marking composition based on inorganic luminophors, method of metal products marking and metal product / 2493192 Composition for marking of metal products produced by powder metallurgy method includes not more than 50% of wt % of luminophor and 50 wt % and more of binding-lubricating agent being fatty acid derivatives or powders of synthetic wax and/or paraffin. Marking of metal products by this composition consists in mixing of alloy metal powder with marking composition, which consists of at least one inorganic agent with property to provide luminescence at irradiation and binding-lubricating agent with subsequent pressing of obtained mixture and its sintering at temperature not exceeding 900°C. |
 Alkali-earth metal silicate based luminophores and method of improving long-term stability thereof / 2507233Disclosed is a luminophore with improved long-term stability, which absorbs radiation in a first wavelength range and emits radiation in a second wavelength range different from the first range, formed in form of grains and contains as a matrix an activator-doped alkali-earth metal silicate of general chemical formula EAxSiyOz, where EA is formed by one or more alkali-earth metals and the condition x, y, z>0 applies, characterised by that the surface of the grains is chemically modified such that at least parts of the surface are formed by a chemical compound of general formula EAuZ2. Z is formed by anions which are capable of chemically bonding with cations of EA and have one or more of the following chemical formulae: SO4 2-, PO4 3-, CO3 2-, C2O4 2-, SiO3 2-, SiH6 2-, where u denotes the ion charge of anions of Z. Also disclosed is a method of improving long-term stability of alkali-earth metal silicate based luminophores. |
 Lighting device / 2519242Invention relates to lighting engineering. The lighting device includes illumination devices (40) which at voltage supply emit primary radiation and solid particles (64, 66) which surround the illumination devices (40) at least by sections and interact with the primary radiation. Concentration of particles (64, 66) changes at least in one direction from the illumination devices (40) from the first concentration section up to the second one. |
FIELD: chemistry.
SUBSTANCE: disclosed is a luminophore with improved long-term stability, which absorbs radiation in a first wavelength range and emits radiation in a second wavelength range different from the first range, formed in form of grains and contains as a matrix an activator-doped alkali-earth metal silicate of general chemical formula EAxSiyOz, where EA is formed by one or more alkali-earth metals and the condition x, y, z>0 applies, characterised by that the surface of the grains is chemically modified such that at least parts of the surface are formed by a chemical compound of general formula EAuZ2. Z is formed by anions which are capable of chemically bonding with cations of EA and have one or more of the following chemical formulae: SO4 2-, PO4 3-, CO3 2-, C2O4 2-, SiO3 2-, SiH6 2-, where u denotes the ion charge of anions of Z. Also disclosed is a method of improving long-term stability of alkali-earth metal silicate based luminophores.
EFFECT: chemical compound formed on the surface of luminophore grains due to chemical modification through low solubility protects the luminophore from moisture, enabling long-term stability thereof.
8 cl, 3 dwg
The invention relates to on the basis of silicate of the alkali earth metal with increased long-term stability of parameters of radiation. These phosphors are used, for example, as a conversion of the phosphors in glowing white light of light sources based on LEDs. The invention also refers to a method of increasing the long-term stability of the phosphors on the basis of silicate of the alkali earth metal.
Phosphors on the basis of silicate of the alkali earth metal differ marked lack of resistance to moisture, therefore their suitability for application in many areas currently severely limited. The main unwanted chemical reaction occurring in luminophores on the basis of ortho-silicates was the alkali earth metal, in the presence of moisture, can be represented by the following equation:
(Ba,Sr,Ca) 2 SiO 4 +2H 2 O G 2(Ba,Sr,Ca)OH 2 +SiO 2 .
Phosphors on the basis of silicate of the alkali earth metal during prolonged storage tend to agglomerate and clumping, which significantly limits their application. In addition, many of the phosphors on the basis of silicate of the alkali earth metal during long-term storage or prolonged use, in particular, based on light emitting diode light sources differ irreversible losses of luminescence and deterioration of performance characteristics. Similar phenomena occur primarily moisture in the air, in connection with which these phosphors are only partly suitable for application in wet areas and use in areas with high humidity.
In the patent GDR DD 293128A5 the method of deposition of protective layers on the phosphors on the basis of halogenide oxide rare earth element. Protective layers are intended to prevent exposure to water, steam, humidity and other environmental factors, and arising during the processing of impacts, and thus allow to exclude the negative impact of these factors on properties of phosphor. Protective layer consists of insoluble crystal or/and .
In the scientific article Guo, C.; Luan, L; Huang, D.; Su, Q., Lv, Y., „Study on the stability of phosphor SrAl 2 O 4 :the Eu 2+ , Dy 3+ in water and method to improve its moisture resistance", Materials Chemistry and Physics, 106(2007), cc.268-272, described increased moisture resistance SrAl 2 O 4 :the Eu 2+ , Dy 3+ , achievable due to heat treatment phosphor through NH 4 HF 2 . It forms a protective layer of strontium fluoride.
The European patent EP 1124913 B1 and international application WO 00/22065 A1 published a way to handle particles emitting red light phosphor on the basis of sulfide of the alkali earth metal, for increase of their resistance. Particles phosphor dispersed in a solvent which contains agent. On phosphor particles formed a liquid symbols " fluorinated coverage.
In the scientific article Guo, C.; Chu, Century, Su, Q.: „Improving the stability of alkaline earth sulfide-based phosphors", Applied Surface Science, 225(2004), cc.198-203, described layering ZnO particles and Al 2 O 3 on the phosphor on the basis of sulfide of the alkali earth metal, Ca 0,8 Sr 0.2 S:Eu 2+ , Tm 3+ .
In the German patent DE 69830180 T2 describes encapsulated particles phosphor, which have mostly transparent layered oxide coating on the base of aluminum oxide. Laminated oxide coating contains aluminum oxide and at least one other metal oxide.
In the German patent DE 102007056343 A1 and international application WO 2009/065480 A1 describes particles phosphor-based (Ca, Sr, Ba) 2 SiO 4 with modified surface coating of metal oxide, nitric transition metal oxide or semimetal and organic coating. Coating of metal oxide, transition metal or semimetal, applied wet chemical method or coated, is intended to bring the surface properties of phosphor in compliance with the chemical properties of the links that are used based on light emitting diode light sources. Chemical interaction with the particles of the phosphor coating is missing.
The European patent EP 1160835 A1 described discharge lamp with layer, preferably containing phosphor, which has the composition BaMgAl 10 O 17 :the Eu. Phosphor preferably covered VA 3 (PO 4 ) 2 or MgF 2 .
In the international application WO 2009/003988 A1 describes the phosphors on the basis of of the alkali earth metal/silicon, such as BaSiN 2 :the Eu, preferably covered by processing through NH 4 F·HF.
The European patent EP 0887397 A1 describes UV phosphors such as VA(Al,Mg) 11 O 19 :Eu 2+ covered , consisting of constructed as double anchors United PO 4-tetrahedra as the basic structural units.
From the German patent DE 19937420 C1 known to the plasma display with layer, preferably contains luminescent composition BaMgAl 10 O 17 :the Eu. Phosphor preferably covered AIP04.
In the international application WO 00/56471 A1 describes how to improve humidity resistance of phosphors, primarily activated europium aluminates strontium. In accordance with the specified manner of grain phosphor processed with the NH 4 F or NH 4 HF 2 .
In the German patent DE 102007053285 A1 describes coated with phosphor particles, which are obtained by mixing at least two and at least one additives wet chemical methods and the subsequent calcination to the initial reagents for phosphor. Coating of metal oxide, transition metal or semimetal put on a phosphor particles wet chemical methods and the subsequent calcining.
In U.S. patent US 2009/050848 A1, in particular, describes the various phosphors on the basis of silicate of the alkali earth metal, preferably covered with nanoparticles of carbonate hydroxide alkali earth metal. For the application of the specified coverage prepare urea and metal source component in the solution.
Proceeding from the U.S. patent US 2009/050848 A1 decisions in the present invention task offer phosphors on the basis of silicate of the alkali earth metal, which have increased long-term stability, first of all, high resistance to water. In addition, you should offer an appropriate way to improve the long-term stability of the phosphors on the basis of silicate of the alkali earth metal.
This task according to the invention solved with the help of phosphor contained in paragraph 1 of the claims. In addition, this problem is solved thanks to the manner specified in a separate item 5 of the claims.
Under the proposed invention phosphor imply the phosphor on the basis of silicate of the alkali earth metal. Therefore, phosphor has a matrix of General chemical formula EA x y Si O z , where x, y, z>0. Component EA formed by one or more alkaline earth metals. The matrix is alloyed with activator, such as the Eu 2+ or Mn 2+ . The matrix can be alloyed with several activators, as well as additional or .
Proposed in the invention of phosphor has the fundamental ability to absorb radiation in the first wavelength range and emit radiation in the second wavelength range, different from the first range. Thus, we are talking about a conversion . In a typical variant of execution of the phosphor absorbs radiation in the blue and/or ultraviolet wavelengths and emits radiation in the visible wavelength range, for example, in the yellow-green, yellow and/or orange range of wavelengths. However, the invention is not limited to certain ranges of wavelengths.
Proposed in the invention of phosphor formed in the form of grains. Grain phosphor formed particles whose diameter is, for example, from 1 to 40 microns. The invention is not confined to certain sizes of particles. The invention relates, in particular, also the grains whose diameter is less than 20 microns.
According to the invention the grain surface of phosphor chemically modified so that at least parts of the surface are formed by chemical compound with the General formula : EA u Z 2 . Z component formed anions, which are capable of chemically to connect with cations EA phosphor. The variable u means a charge of anions Z, preferably 2 or 3 and in any case greater than 0. In case if the variable and means an even number, total formula can be represented also as a formula mathematically reduced coefficients. Proposed in the invention of phosphor differs in that the surface of grains chemically modified. Chemical modification causes a chemical compound contained in the matrix of the alkali earth metal. Ions of alkali earth metal matrix chemically connected with anions Z at least on the surface areas of grains. Thus, under the chemical modification involve not cover exclusively physical actions, for example, applied to the grain phosphor by chemical or physical vapour deposition. Another difference from such coverage is that proposed in the invention of chemical modification not necessarily should be carried out on the entire surface of the grains of the phosphor. Enough, if a chemical bond with the General formula EA u Z 2 have lots of grain surface phosphor. Due to the limited speed of diffusion of such chemical compound prevents, respectively slows the flow of water in grain phosphor and/or yield of the reaction with water from the seeds of the phosphor. Chemical compound, formed on the surface of grains due to chemical modification, preferably has a low solubility, thanks to which phosphor extremely long hours is protected from moisture condition.
According to the invention alkaline earth metal EA matrix phosphor chemically connected with anions Z at least on the surface areas of grains. Anions Z formed in the form of molecules anions. Specialists can choose suitable anions in conformity with the specific composition of matrix and selected for the chemical modification of the method.
Connection EA u Z 2 can be derived, for example, (Sr,Ba,Ca)SO 4 , (Sr,BA,CA) 3 (PO 4 ) 2 , (Sr,BA,CA)3 , (Sr,BA,Sa), C 2 O 4 , (Sr,BA,CA)SiO 3 or (Sr,Ba,Ca)SiF 6 .
In addition, the proposed invention phosphor differs that is present on the surfaces of grains chemical compound of General formula EA u Z 2 transparent or at least the most transparent for radiation in the first band of wavelengths and radiation in the second wavelength range. Therefore, chemical modification of the surface of grains does not limit the effectiveness of the phosphor. In particular, the chemical compound of the General formula EA u Z 2 is unable to absorb radiation with wavelength 380 nm.
Advantage of the proposed invention phosphor is the possibility of its economic production, as well as the possibility of running according to the invention of chemical modification of the surface of the variation methods, adapted to the specific and specific application.
Anions have one or several of the following chemical formula: SO 4 2- , PO 4 3- , 3 2 , C 2 O 4 2- , SiO 3 2 - and SiF 6 2- . Anions specified formulas are especially suitable for chemical compound with cations of alkali earth metal and formation on the surface of grains phosphor transparent, sparingly soluble modifications of the phosphor. In the case of anions SO 4 2- , 3 2 , C 2 O 4 2- , SiO 3 2 - and SiF 6 2 - variable and means 2. In the case of anions PO 4 3 - variable and means 3.
In a preferred embodiment, the proposed invention phosphor matrix has the formula (Ba a ,Sr b ,Ca c ) 2 SiO 4 . At least one of the variables a, b and C means a number greater than 0, and the sum of a+b+C is 1. Under such phosphor imply of the alkali earth metal, which is particularly suitable for use in light sources based on LEDs.
In another preferred embodiment, the proposed invention phosphor component of the EA matrix contains magnesium and other alkaline earth metal. Under this option matrix has one of the following chemical formula: EA' 3 MgSiO 8 , EA' 2 MgSi 2 O 7 or EA' 2 MgSiO 5 , and EA formed by one or more alkaline earth metals, excluding magnesium.
In accordance with other better options in the performance of the proposed invention phosphor matrix has the chemical formula EA 3 SiO 5 or EASiO 3 .
In accordance with the special version proposed in the invention of phosphor in each case the whole surface of grains formed chemical compound with the General formula : EA u Z 2 . Therefore, chemically modified surfaces of all grains.
Part of silicon in silicate alkali earth metal, may be replaced by aluminum, boron, germanium, gallium and/or phosphorus. Such a possibility of modification of the phosphors on the basis of silicate of the alkali earth metal known to specialists. Modified similarly phosphor specialists are always also called silicate of the alkali earth metal, and in most cases indicate the General formula EA x Si y O. For especially accurate specialists lead the General formula EA x (Si, Al, B, Ge, Ga, P) y O z or formula EA x (Si 1-e-f-g-h-i Al e B f Ge g Ga h P i y O z , where e, f, r, h, and/or i>0. Another possible modification of the phosphors on the basis of silicate of the alkali earth metal is the introduction of up to 10% mol. halogen ions.
Proposed in the invention of a way to improve long-term stability of phosphors, especially phosphors on the basis of silicate of the alkali earth metal. Matrix such phosphors has a General chemical formula EA x y Si O z , the cations EA formed by one or more alkaline earth metals and with x, y, z>0. Subject to the improvement of phosphor is in the form of grains. Proposed in the invention of the way first involves the stage at which choose the chemical that gives anions, which may be chemically connected with cations EA phosphor. Under the chemical imply, for example, a chemical element or chemical compound, located in solid, liquid or gaseous state. Under the chemical also involve a mixture of substances, for example, aqueous solution. For the implementation of the proposed invention in a way it is important that the chemical had the ability to emit anion, which could chemically connected with cations of alkali earth metal. At the next stage of the invention of the method of chemical subject to mixing with grains of phosphor, the purpose of which is preparation for the chemical interaction of chemical substances, primarily released a chemical substance anions, with the surface of grains phosphor, first of all with her cations of alkali earth metal. Conditions for the further implementation of the method should provide the possibility of occurrence of specified chemical reaction. To do this, mixed with a chemical agent grain phosphor subject, for example, heat, stirring and exposed to the atmosphere. Specialists choose the conditions that must be the chemical and specific composition of silicate of the alkali earth metal. The chemical reaction can proceed in accordance with the equation:
uEA 2+ +2Z u- →EA u Z 2 .
Z component means anions. The variable u means a charge of anions Z, preferably 2 or 3 and in any case greater than 0. Reaction primarily runs on free surfaces of grains phosphor. As you increase the thickness of the modified zones EA u Z 2 is the decrease of the reaction rate, and decisive impact on the total transformation provides diffusion. Simultaneously this interaction determines the preferred formation of dense zones EA u Z 2 instead of point formations. At the next stage of the invention a method of grain phosphor after a chemical reaction shall be processed, namely separation performed, for example, by washing, drying, or separation from the gas stream.
Proposed in the invention method provides a cost-effective and adaptable to the real conditions of the possibility of a significant increase in long-term stability of the phosphors on the basis of silicate of the alkali earth metal. An important fact is that thermodynamic reasons transformation cations EA grains phosphor with anions Z chemical flows with increased speed in the energetically preferred places that also have a special penchant for interaction with water. The result prevents interaction with water blocking these energetically preferred places achieved by the above modification, is to significantly improve humidity resistance of grains phosphor. The final result of the continuation of the reaction between grains of phosphor and a chemical substance is a total change of the surface and a significant increase in long-term stability of the material. The thickness of the modified surface layer is proportional to the reactivity of the original surface. Thus, this is isotropic stabilization modified grains and the lack of places of detention prevailing moisture.
Provided chemical anions should be able to chemically connected with cations of alkali earth metal. The chemical should be chosen in such a way that, on the one hand, provided they anions formed with cations of alkali earth metal, chemical compound having a particularly low solubility and high transparency. On the other hand, a chemical substance should be chosen so that was possible provided by a chemical reaction between a chemical substance anions and cations EA alkali earth metal. First of all suitable chemicals, which provide anions with chemical formulas SO 4 2- , PO 4 3 -, 3 2 , C 2 O 4 2- , SiO 3 2 - and SiF 6 2- .
In accordance with the first preferred option proposed in the invention of the method of chemical reaction implement in water suspension. The choice of a chemical shall be implemented by the fact that choose soluble containing anions chemical compound and dissolve it in water. Blending of grains phosphor with a chemical substance shall be implemented by the fact that the grain is injected into an aqueous solution, and water solution mix. Separation of grains phosphor preferably carry out primarily by , filtration or centrifugation. In conclusion, perform drying. Before drying of grain, if necessary, shall be washed with water and suspended in ethanol.
In the alternative preferred embodiment of the proposed invention method for surface modification grains implement reactions between solid particles and gas phases. You should choose a chemical substance in the form of gas, such as gaseous SO3 . Blending of grains phosphor with a chemical substance shall be implemented by the fact that provide flushing grains gas, for example, expose located in the furnace of grain influence of the gas flow.
In another alternative proposed in the invention of the method of chemical modification by means of two reactions are dry solids. The choice of a chemical shall be implemented by the fact that choose containing anions powder chemical compound. Blending of grains phosphor with a chemical substance shall be implemented by the fact that the grain is mixed with powdered chemical compound and homogenize the mixture, realizing preparation of a chemical reaction.
Other advantages of details and refined derive from the following description of the preferred embodiments of the invention with reference to the annexed to the description of the diagrams below:
figure 1 - chart long-term stability proposed in the invention of the modified phosphor on the basis of silicate of the alkali earth metal,
figure 2 - chart of long term stability proposed in the invention of the modified solution of ammonium carbonate phosphor on the basis of silicate of the alkali earth metal, and
Figure 1 shows a comparison chart of long-term stability of the modified phosphor on the basis of silicate of the alkali earth metal, with long-term stability of the phosphor on the basis of silicate of the alkali earth metal, according to the level of technology. For the proposed in the invention of the modification of surfaces of grains of phosphor on the basis of silicate of the alkali earth metal, prepare a solution of (NH 4 ) 2 SiF 6 in deionized water. To 200 ml prepared aqueous solution with stirring, add 50 grams of phosphor on the basis of silicate of the alkali earth metal (Ba, Sr, Ca, Mg) 2 SiO 4 :the Eu. Aqueous solution heat up and maintain the temperature at a constant level (25 degrees C). After 20 minutes, stirring cease. Then thrice rinse the surface of grains of chemically modified silicate alkali earth metal by water. Suspended phosphor on the basis of silicate of the alkali earth metal sucked off and finally dried at 105°N Specific parameters of the experiment are not limited to the above values. Modified surface consists of predominantly fluorosilicate preparation of the alkali earth metal EASiF 6 . Curve 01 represents the dependence of the relative intensity of the radiation in the percentage of the storage duration, in hours at a temperature of 60 C and humidity 90%. The relative intensity of emission proposed in the invention of the modified phosphor on the basis of silicate of the alkali earth metal exceeds 90% after storage for a period of more than 1000 hours. In addition, figure 1 shows the curve 02, representing the dependence of the relative intensity of emission of unmodified phosphor on the basis of silicate of the alkali earth metal, according to the level of equipment from the storage duration, in hours at a temperature of 60 C and humidity 90%. As is evident from the character of the curve 02, the relative intensity of emission of phosphor according to the level of equipment already after a few dozen hours falls to a value less than 60%.
Figure 2 shows a comparison chart of long term stability proposed in the invention of phosphor on the basis of silicate of the alkali earth metal, modified solution of ammonium carbonate, with long-term stability of the phosphor on the basis of silicate of the alkali earth metal, according to the level of technology. For the proposed in the invention of the modification of phosphor solution of ammonium carbonate first prepare a solution NH 4 HCO 3 in deionized water. To 200 ml prepared aqueous solution with stirring, add 25 g phosphor on the basis of silicate of the alkali earth metal, General formula (BA, Sr, CA) 3 MgSi 2 O 8 :the Eu. Aqueous solution heat up and maintain the temperature at a constant level (40 C). After 60 minutes to complete mixing. Modified silicate of the alkali earth metal, washed three times by water is drawn off, and finally dried at 105°C. Specific parameters of the experiment are not limited to the above values. Modified surface is mainly calcium carbonate alkali earth metal 3 . Dependence of the relative intensity of emission modified accordingly proposed in the invention of phosphor on the basis of silicate of the alkali earth metal storage time in hours at a temperature of 60 C and humidity of 90% is represented as a curve 04. The relative intensity of emission of the specified proposed in the invention of phosphor on the basis of silicate of the alkali earth metal, with the duration of their storage component of several hundreds of hours is almost 100%. In contrast, the relative intensity of emission of unmodified phosphor on the basis of silicate of the alkali earth metal, according to the level of techniques depending on the storage duration, in hours (curve 09) after storage in less than 100 hours is only about 70%.
In the alternative preferred embodiment of the proposed invention method for surface modification of grains of phosphor on the basis of silicate of the alkali earth metal implement chemical reactions between solid particles and gas phases. Such modification can be, for example, by heating 25 g phosphor on the basis of silicate of the alkali earth metal formula (Ba, Sr, Ca) 2 MgSi 2 O 7 :the Eu up to 200 C in the boat aluminum oxide in the furnace in a stream of nitrogen with volumetric flow rate of 5 l/min Flowing through the tube furnace nitrogen before entering the furnace moisturize by barbotirovaniya through the water-filled wash bottle. After heating phosphor on the basis of silicate of the alkali earth metal, up to 200 C to the furnace is the second gas flow SO 3 with a maximum volumetric flow rate of 1 l/min Both gas flow around the phosphor on the basis of silicate of the alkali earth metal, that provides the possibility of occurrence of a chemical reaction modification grains phosphor. After a 30-minute reaction supply of gaseous SO 3 and the supply of the heat stop, and phosphor cools down quickly in an atmosphere of nitrogen. In the boat aluminum oxide is proposed in the invention modified phosphor on the basis of silicate of the alkali earth metal. Instead of the flow of gaseous SO 3 can also be a stream of carbon dioxide gas.
Figure 3 shows a comparison chart of long-term stability of the modified ammonium fluoride phosphor on the basis of silicate of the alkali earth metal (not in accordance with the invention) with long-term stability of unmodified phosphor on the basis of silicate of the alkali earth metal, according to the level of technology. When added phosphor ammonium fluoride react two in a dry condition solid powdery substances. According to this example of 25 g phosphor on the basis of silicate of the alkali earth metal, General formula (BA, Sr, CA, Mg) 3 SiO 5 :the Eu is mixed with 10 g of finely ground NI-UF, and homogenize the mixture. Mix in the boat aluminum oxide placed in a tube furnace and slowly heated to a temperature of 300 OC in a stream of nitrogen with volumetric flow rate of 5 l/min Mixture is left in the specified conditions for 30 minutes and then cooled rapidly. Curve 12 represents the dependence of the relative intensity of emission of the specified modified phosphor on the basis of silicate of the alkali earth metal storage time in hours at 85 C and relative humidity of 85%. The progress curve 12 shows the relative intensity of emission of phosphor after 150 hours of storage almost not reduced and accounts for more than 90%. Curve 13 is the dependence of the relative intensity of emission of unmodified phosphor on the basis of silicate of the alkali earth metal, according to the level of equipment from the storage time in hours at 85 C and relative humidity of 85%. Already after 150 hours of storage relative intensity of phosphor on the basis of silicate of the alkali earth metal is reduced to a value less than 70%.
The described method is suitable for the surface modification of grains phosphor fluoride or carbonate using appropriate ammonium compounds.
Designation
01 Curve of long-term stability of the modified phosphor on the basis of silicate of the alkali earth metal
02 Curve of long term stability of phosphor on the basis of silicate of the alkali earth metal, according to the level of technology
04 Curve of long-term stability of the modified solution of ammonium carbonate phosphor on the basis of silicate of the alkali earth metal
09 Curve of long term stability of phosphor on the basis of silicate of the alkali earth metal, according to the level of technology
12 Curve of long-term stability of the modified ammonium fluoride phosphor-based silicate alkali earth metal
13 Curve of long term stability of phosphor on the basis of silicate of the alkali earth metal, according to the level of technology
1. Phosphor with high long-term stability, absorbing radiation in the first wavelength range and emits radiation in the second wavelength range, different from the first range, with a phosphor formed in the form of grains and as a matrix contains doped activator silicate of the alkali earth metal, General chemical formula EA x y Si O z , and EA formed by one or more alkaline earth metals and true condition x, y, z>0, characterized in that the surface of grains chemically modified by the fact that at least parts of the surface are formed by chemical compound with the General formula : EA u Z 2 , where Z is formed anions, which are capable of chemically to connect with cations of EA and have one or more of the following chemical formulas: SO 4 2- , PO 4 3- , CO 3 2 - 2 Of 4 2- , SiO 3 2- , SiF 6 2- , and moreover, u mean ion charge anions Z.
4. Phosphor one of claims 1 to 3, characterized in that in each case the whole surface of grains formed chemical compound with the General formula : EA u Z 2 .
5. A way to increase long-term stability of phosphors, formed in the form of grains and containing as a matrix of silicate of the alkali earth metal, General chemical formula EA x y Si O z , and EA formed by one or more alkaline earth metals and fair condition x, y, z>0, which includes the following stages: - the choice of chemical substances, which provides anions which capable of chemically to connect with cations of EA and have one or more of the following chemical formulas: SO 4 2- , PO 4 3- , WITH 3 2 - 2 Of 4 2- , SiO 3 2- , SiF 6 2 - - the blending of grains phosphor with a chemical agent, - to prepare the conditions for the chemical reaction between the chemical substance and the surface of the particles phosphor; and separation of grains phosphor.
6. The method according to claim 5, wherein is the choice of a chemical shall be implemented by the fact that choose containing anions chemical compound and dissolve it in water, blending of grains phosphor with a chemical substance shall be implemented by the fact that the grain is injected into an aqueous solution, which is subjected to the inward and - separation of grains phosphor carried out by drying of grains.
7. The method according to claim 5, wherein opt for a chemical substance in the form of gas, and the blending of grains phosphor with a chemical substance shall be implemented by the fact that provide runaround grains gas.
8. The method according to claim 5, wherein is the choice of a chemical shall be implemented by the fact that choose containing anions powder chemical compound, and the blending of grains phosphor with a chemical substance shall be implemented by the fact that the grain is mixed with powdered connection and homogenize the mixture.