RU2707840C1 - Method of producing highly stoichiometric nano-sized precursor for synthesis of solid solutions of yttrium-aluminium garnet with rare-earth element oxides - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to the technology of producing compounds of complex oxides with a garnet structure containing rare-earth elements, for use in the technology of synthesis of optical ceramic materials of laser quality when creating active bodies of solid-state lasers of different geometries. Solution of chlorides or sulphates of yttrium, aluminium and rare-earth metal cations is sprayed into a mixture of aqueous ammonia solution with 25 % concentration and crystalline carbamide in amount of 90–100 g per 1 l of aqueous ammonia solution of 25 % concentration, cooled to 0 °C. Obtained residue is decanted in deionised water to pH = 7. Moist precipitate is dried in vacuum drying cabinet at temperature of 60–80 °C.

EFFECT: as a result of calcination at 1000 °C 100 % of the desired product (cubic aluminium-yttrium garnet) is obtained from such a precursor, which does not contain extraneous phases, which considerably worsen all main characteristics: transparency, refraction index, transmission area, laser generation.

5 cl, 5 ex, 1 tbl

Description

The invention relates to a technology for the production of compounds of complex oxides with a garnet structure containing rare-earth elements (REE), which can be used in the synthesis of optical ceramic materials of laser quality when creating active bodies of solid-state lasers of various geometries. The method is carried out by the method of precipitation by introducing the starting compounds of aluminum, yttrium and alloying elements into the precipitant, followed by isolation of the precipitated product and calcining the obtained powdery product at 1000 ° C, while the precipitation is carried out using the main precipitator, and aqueous ammonia the zone of which is introduced crystalline urea (urea) in an amount of 80-100 g per 1 liter of precipitant to block the solubility of aluminum hydroxide in ammonia, and then with stirring DYT aqueous mixtures of salts of aluminum chloride, yttrium, and alloy elements in a quantity corresponding to a molar ratio of metal cations from the general formula (Y _1-x RZEh) ₃ Al ₅ O _12, and the resulting reaction mixture was stirred at a speed of 300-500 rev / min . The isolated precipitated product is first washed with water to pH = 7-7.5, then with 2-3 portions of acetone, 80-100 ml each.

Highly stoichiometric nanosized powders of a solid solution precursor based on a binary compound of yttrium-aluminum garnet (YAG) doped with rare earth ions were obtained by chemical reverse deposition followed by drying and calcination to synthesize a homogeneous monophasic cubic solid solution.

As ligands for obtaining a solid solution based on a binary compound of yttrium-aluminum garnet (Y ₃ Al ₅ O ₁₂ ), oxides or rare-earth element compositions are used: Er ₂ O ₃ ; Yb ₂ O ₃ ; Tm ₂ O ₃ ; Ho ₂ O ₃ ; Er ₂ O ₃ —Tm ₂ O ₃ compositions; Er ₂ O ₃ —Ho ₂ O ₃ ; Er ₂ O ₃ —Tm ₂ O ₃ —Ho ₂ O ₃ ; Yb ₂ O ₃ -Tm ₂ O ₃ ; Yb ₂ O ₃ —Tm ₂ O ₃ —Ho ₂ O ₃ ; Yb ₂ O ₃ -Ho ₂ O ₃ , which are introduced into the composition of yttrium-aluminum garnet in the range of 1.0-50.0 at. % relative to the yttrium atom.

With the introduction of rare earth oxides (ORE) or their compositions into the composition of yttrium-aluminum garnet, solid solutions are formed that replace only yttrium cations with REE cations. Therefore, the calculations of the compositions are carried out based on the formula of the solid solution Y _3-X Me _X Al ₅ O ₁₂ , where x is the fraction of the ORZE cation or the sum of the proportions of the ORZE cations introduced into the composition of yttrium-aluminum garnet and substituted yttrium cations.

The known method (US Patent US 5,484,750 (A) Transparent polycrystalline garnets Applicant: GEN ELECTRIC [US] IPC: C09K 11/00; C09K 11/77; C09K 11/80; G01T 1/20; G01T 1/202, publication date: 01/16/1996) obtaining a transparent polycrystalline solid-state scintillation material with a YAG structure doped with rare-earth ions, including dissolution of the initial cations of salts, evaporation to a concentrated state, co-coprecipitation by sputtering, followed by filtration of the precursor precipitate, decantation, drying, and heat treatment way b includes the following stages in which:

- a mother liquor of cations of salts of a given composition is formed by dissolving yttrium, aluminum and rare-earth metal chlorides in concentrated hydrochloric acid when heated, then evaporated and sprayed into a basic solution of ammonium oxalate, the precipitate is decanted in deionized water and / or alcohol to remove excess ammonium hydroxyl and / or ammonium carbonate and reaction products, the precipitate is dried at a temperature of about 110 ° C by vacuum drying and calcined in air at a temperature of 750 ° C;

- after thermal decomposition, the powder is ground in a jet mill or in a planetary mill using zirconia as a grinding tool in isopropyl alcohol, then dried and granules are obtained;

- after granulation, the powder is formed by isostatic pressing to obtain samples with a relative density of 55%;

- the obtained samples are subjected to vacuum sintering at a temperature of 1400-1600 ° C;

- after vacuum sintering, the samples are subjected to hot isostatic pressing at a temperature of 1350-1600 ° C; after which ceramic samples are mechanically ground and polished.

The disadvantage of this technical solution is the synthesis of the precursor in an excess of ammonium hydroxyl and, when this excess is removed, a certain amount of aluminum cations is removed in the form of soluble ammonia, which ensures the stoichiometry of the target product.

Invention (Method for producing small-crystalline undoped and doped yttrium-aluminum garnet, Application of the Russian Federation RU 2137867 C1, IPC: СЗ0В 7/10, С30В 29/28, C01F 7/02, C01F 17/00, Priority date: 04/22/1998) the synthesis of inorganic materials and is used to obtain a mixture for growing YAG single crystals used as active media in solid-state lasers, and such in the manufacture of high-temperature ceramics. The inventive hydrothermal treatment of a stoichiometric mixture of yttrium and aluminum oxides is carried out in 1-3% aqueous solutions of activators, which use alkali metal and ammonium salts of saturated organic acids (C1-C3), at 270-360 ° C and P _H2O = 56-190 atm. Doped YAG is obtained by introducing additives of neodymium or chromium-containing components into the initial oxide mixture. The invention improves the yield of this product. The environmental friendliness of the synthesis method and the purity of the resulting crystals are due to the one-stage process and the integrity of the autoclave.

The disadvantage of the described invention is the use of salts of alkaline earth metals and organic acids (C1-C3), which leads to the incorporation into the crystal lattice of ions of alkaline earth metals and the deterioration of the lasing properties of high-temperature ceramics. Anions of organic acids (C1-C3) are the "suppliers" of free carbon, which leads to the appearance of a "gray" filter. Carrying out the process at 270-360 ° C promotes strong agglomeration of the resulting product and, as a result, violates the stoichiometry of the precursor.

A known method of producing small-crystalline undoped and doped yttrium-aluminum garnet (Patent for invention of the Russian Federation RU 2137867, class IPC C30V 7/10, C30B 29/28, C01F 7/02, C01F 17/00, publ. 09/20/1999, application for invention JP2001270775, class IPC СВВ 35/44, publ. 02.10.2001), hydrothermal treatment of a stoichiometric mixture of yttrium and aluminum oxides is carried out in 1-3% aqueous solutions of activators, which are used alkali metal and ammonium salts of saturated organic acids (C1-C3), at 270-360 ° С and P _H2O = 56-190 atm. Doped YAG is obtained by introducing additives of neodymium or chromium-containing components into the initial oxide mixture.

The disadvantage of the described invention is the use of salts of alkaline earth metals and organic acids (C1-C3), which leads to the incorporation into the crystal lattice of ions of alkaline earth metals and the deterioration of the lasing properties of high-temperature ceramics. Anions of organic acids (C1-C3) are the "suppliers" of free carbon, which leads to the appearance of a "gray" filter. Carrying out the process at 270-360 ° C promotes strong agglomeration of the resulting product and, as a result, violates the stoichiometry of the precursor.

Various methods for producing transparent ceramic are known (D.O. Lemeshev et al., The prospect of creating new optically transparent materials based on yttrium oxide and yttrium-aluminum garnet, Glass and Ceramics magazine, 2008, No. 4, pp. 25-27) materials based on yttrium-aluminum garnet, for example, sol-gel technology, thermal decomposition of salts, solid-phase synthesis, hydrothermal synthesis, freezing, coprecipitation, combustion.

The cited article does not provide specific technical solutions, but describes the prospect of creating new optically transparent materials based on yttrium oxide and yttrium-aluminum garnet.

Described (US Application US 2009/081100 (Al) Translucent material and manufacturing method of the same. Applicant: FUJIFILM CORP [JP] IPC: C01F 17/00; C04B 35/44; C04B 35/64; H01S 3/16, date publication: March 26, 2009, application for invention CN 101386531, class IPC С04В 35/622, С04В 35/50, С04В 35/44, published March 18, 2009) methods for producing yttrium-aluminum garnet and transparent polycrystalline solid-state scintillation material with a structure YAG doped with rare-earth ions, in which the mother liquor of cations of salts of a given composition is formed by dissolving the chlorides or sulfates of the desired cations (it (aluminum, rare-earth metals) in water when heated, then evaporated and sprayed into an aqueous solution of ammonia, the precipitate is decanted in deionized water, the suspension is poured into a container, the molded body is formed by slow deposition, the resulting body is then sintered at 1750 ° C.

The main disadvantages of these methods are: 1) high agglomeration of the obtained powder materials; 2) capture agglomerates of uterine solutions through intergrain spaces; 3) the formation of globules during spraying, which contain unreacted stock solutions; 4) the synthesis of the precursor in an excess of ammonium hydroxyl and, therefore, when this excess is removed, a certain amount of aluminum cations is removed in the form of soluble ammonia, which ensures stoichiometry of the target product.

A known method for producing a transparent ceramic material (RF Patent for the invention RU 2473514, class IPC С04В 35/505, С04В 35/622, С30В 29/28), comprising mixing the preformed matrix with preformed filler, molding the mixture and heat treatment.

The disadvantage of this invention is the use of a matrix made in the form of a solid solution of scandium oxide in yttrium oxide and a filler made in the form of a solid solution of scandium oxide in yttrium-aluminum garnet. In addition, this method involves a multi-stage process and numerous grinding processes, which leads to the grinding of the material of grinding media, which leads to the appearance of undesirable second phases.

A known method of producing a transparent ceramic material based on yttrium oxide doped with trivalent metals, with the addition of yttrium-aluminum garnet (Application for invention of the Russian Federation RU 2009115895, class IPC С30В 29/00, publ. 10.11.2010), which consists in the fact that the original the material is obtained by the method of reverse heterophase deposition, while to obtain yttrium-aluminum garnet, a mixture of yttrium and aluminum hydroxides is used, which is ground and then the scandium salt is introduced, after which thermal decomposition is carried out and ground, the second component, the first and second components are mixed, the resulting mixture is heated, then the preforms are formed by the method of dry pressing, after which they are heated to remove the technological bond, and placed in a vacuum oven, after which the transparent ceramic material is ground and polished.

The disadvantage of this method is the production of highly agglomerated hydroxides and numerous grinding processes, which leads to the grinding of the material of grinding media, which leads to the appearance of undesirable second phases, which leads to disruption of the stoichiometry of the materials obtained.

A known method of producing aluminum yttrium garnet doped with rare earth elements (Patent for the invention of the Russian Federation RU 2503754, class IPC С30В 29/28, C09K 11/80, publ. 10.01.2014), which is carried out by the deposition method by introducing the starting compounds of aluminum, yttrium and alloying elements into the precipitant, followed by isolation of the precipitated product and calcination of the obtained powdery product, while the precipitation is carried out in the presence of a fluorine-containing additive, and ammonium bicarbonate is used as the precipitant, in an aqueous solution of which mixing, a mixed aqueous solution of aluminum nitrate, yttrium and alloying elements is introduced, after which the resulting reaction mixture is stirred and the precipitated product separated is washed with water, dried and calcined.

The disadvantage of this method is the use of a fluorine-containing additive, the fluoroanions of which lead to deliberate particle agglomeration due to the formation of fluoride "bridges", and the appearance of a second phase in the form of yttrium fluorides and rare earth elements, which leads to a violation of the stoichiometry of the materials obtained.

There is also a method of producing nanosized powder of yttrium aluminum garnet (RF Patent RU 2576271 C1, IPC: C01F 17/00, B82B 1/00, B82Y 30/00, priority 23.12.2014). The invention relates to a technology for producing compounds of complex oxides with a garnet structure, which can be used for the manufacture of elements of solid-state lasers of the near and middle IR ranges, for the development of scintillators and phosphors, as well as in the manufacture of heat-resistant ceramics. A method of obtaining nanosized powder of yttrium aluminum garnet involves preparing the initial reaction aqueous solutions containing yttrium (III) and aluminum salts in a molar ratio of 3: 5. First, the precipitating reagent, which is used as a strongly basic gel anion exchange resin AB-17-8 in hydroxide form, is brought into contact with a solution of yttrium (III) salts at room temperature for 20 minutes, then a solution of aluminum (III) salts is added. A precursor product is precipitated from the resulting solution, it is separated from the solution, washed with water, dried and calcined at a temperature of 900 ° C. The ion-exchange method provides the production of nanoscale powder of yttrium aluminum garnet, which does not contain precipitating cations, without the use of aggressive media and pressures.

The disadvantages of the described invention include the use as a precipitant of strongly basic gel anion exchange resin AB-17-8 in hydroxide form, which leads to the formation of highly soluble aluminum ammonia. When washing the precursor product, highly soluble aluminum ammonia passes into the mother liquor, which leads to a violation of stoichiometry for aluminum.

Closest to the proposed invention in technical essence and the achieved result is a method for producing a transparent polycrystalline solid-state scintillation material with a YAG structure doped with rare earth ions (US Application US 2009/081100 (A1) Translucent material and manufacturing method of the same. Applicant: FUJIFILM CORP [JP] IPC: C01F 17/00; C04B 35/44; C04B 35/64; H01S 3/16, publication date: 03/26/2009), in which the mother liquor of cations of salts of a given composition is formed by dissolving the chlorides or sulfates of the desired cations ( yttrium, and luminescence and rare-earth metals) in water when heated, then evaporated and sprayed into an aqueous solution of ammonia, the precipitate is decanted in deionized water, the suspension is poured into a container, the molded body is formed by slow deposition, the resulting body is then sintered at 1750 ° C.

The disadvantage and very serious disadvantage of this method is that in the process of precipitation of the precursor in the form of triple hydroxides of yttrium, aluminum and the corresponding REE in a system containing a significant excess of ammonia, the following reactions occur:

Al ₂ (SO ₄ ) ₃ + 6NH ₄ OH → 2Al (OH) ₃ +3 (NH ₄ ) ₂ SO ₄ ,

or AlCl ₃ + 3NH ₄ OH → Al (OH) ₃ + 3NH ₄ Cl,

and then Al (OH) ₃ + 2 (NH ₄ ) ₂ SO ₄ + → AlNH ₄ (SO ₄ ) ₂ + 3NH ₄ OH,

or Al (OH) ₃ + 4NH ₄ Cl → AlNH ₄ Cl ₄ + 3NH ₄ OH

with the formation of soluble complex salts of aluminum ammonium sulfate or aluminum ammonium chloride. For example, the solubility of aluminum-ammonium sulfate AlNH ₄ (SO ₄ ) ₂ in water is 2.1 g per 100 g of water at 0 ° C and 7.74 g per 100 g of water at 20 ° C, which does not allow to obtain a highly stoichiometric precursor corresponding to the general formula (Y _1-x Me _x ) ₃ Al ₅ O ₁₂ , where x is the fraction of the cation of the rare-earth element or the sum of the fractions of the rare-earth cations. As a result of the calcination of such a precursor at 1750 ° C, the target product (cubic aluminum yttrium garnet) contains other phases such as YAlO ₃ and Y ₄ Al ₂ O ₉ , which sharply worsen all the main characteristics: transparency, refractive index, transmission region, laser generation.

In order to eliminate these drawbacks, we propose a method for producing a highly stoichiometric nanoscale precursor for the synthesis of solid solutions of yttrium-aluminum garnet with rare-earth oxides, which consists in the fact that the starting material is obtained by reverse heterophase deposition by dissolving the chlorides or sulfates of the required cations (yttrium, aluminum and rare-earth metals ) in water when heated, then evaporated and sprayed into an aqueous solution of ammonia. To prevent the formation of water-soluble complex salts, aluminum ammonium sulfate or aluminum ammonium chloride is added to the precipitant crystalline urea (urea) in an amount of 80-100 g per 1 liter of precipitant to block the solubility of aluminum hydroxide in ammonia. In this case, the following process takes place in the system:

AlNH ₄ (SO ₄ ) ₂ + 2CO (NH ₂ ) ₂ + 6H ₂ O → 2 (NH ₄ ) ₂ SO ₄ + 2CO ₂ + NH ₄ OH + Al (OH) ₃ .

The precipitate is decanted in deionized water to pH = 7. The resulting precursor is squeezed on a Buchner funnel and washed again on a Buchner funnel 2-3 times with high-purity acetone. After pressing, the obtained precursor powder is transferred from the Buchner funnel to the tracing paper and the tracing paper with the precursor powder is placed in a vacuum oven and dried at a temperature of 60-80 ° C for at least 8 hours.

The technical result that can be achieved using the proposed technical solution is to provide a highly stoichiometric precursor, from which, as a result of calcination, a product containing only one phase of cubic yttrium aluminum garnet doped with rare-earth ions is obtained.

The proposed method differs from the known use in the composition of the precipitant (aqueous ammonia) of crystalline urea in the amounts described in the inventive method. This is followed by washing in the last stages of decantation and on a Buchner funnel, which generally determines the solution of the goal of the invention.

The inventive composition is illustrated by examples of specific performance.

Example 1. (prototype) Prepare a stock solution of cations of salts of a given composition, based on the formula (Y _1-x REE _x ) ₃ Al ₅ O ₁₂ , by dissolving the chlorides or sulfates of the desired cations (yttrium, aluminum and rare earth metals) in water at heating, then evaporated and sprayed into an aqueous solution of ammonia, the precipitate is decanted in deionized water. The resulting precipitate is dried in a vacuum oven at a temperature of 60-80 ° C. As a result of calcination at 1000 ° C of such a precursor, the target product (cubic yttrium aluminum garnet) contains 86 mass. % (Y _1-x REE _x ) ₃ Al ₅ O ₁₂ , other phases such as YAlO ₃ (4 wt.%) And (Y _1-x REE _x ) ₄ Al ₂ O ₉ (10 wt.%). Such impurities (table 1, sample 1) sharply worsen all the main characteristics: transparency, refractive index, transmission region, laser generation.

Example 2. Prepare a stock solution of cations of salts of a given composition, based on the formula (Y _1-x REE _x ) ₃ Al ₅ O ₁₂ , by dissolving the chlorides or sulfates of the desired cations (yttrium, aluminum and rare-earth metals) in water when heated, then evaporate to reduce the initial volume by 2 times (solution temperature 125 ° C). A mixture of an aqueous solution of ammonia of 25% concentration and crystalline urea is prepared separately at a rate of 80 g per 1 liter of an aqueous solution of ammonia of 25% concentration. The resulting solution of chlorides or sulfates of the required cations (yttrium, aluminum and rare-earth metals) is sprayed into a mixture of an aqueous solution of ammonia of 25% concentration and crystalline urea based on 80 g per 1 liter of an aqueous solution of ammonia of 25% concentration, cooled to 0 ° C. The precipitate obtained is decanted in deionized water to pH = 7. The resulting precursor is squeezed on a Buchner funnel and washed again on a Buchner funnel 2-3 times with high-purity acetone. The wet cake is dried in a vacuum oven at a temperature of 60 - 80 ° C. As a result of calcination at 1000 ° C of such a precursor, the target product (cubic yttrium aluminum garnet) contains 89.7 mass. % (Y _1-x REE _x ) ₃ Al ₅ O ₁₂ , other phases such as YAlO ₃ (6 wt.%) And Y ₂ O ₃ (4.3 wt.%). Such impurities (table 1, sample 2) significantly worsen all the main characteristics: transparency, refractive index, transmission region, laser generation.

Example 3. Prepare a stock solution of cations of salts of a given composition, based on the formula (Y _1-x REE _x ) ₃ Al ₅ O ₁₂ , by dissolving the chlorides or sulfates of the desired cations (yttrium, aluminum and rare-earth metals) in water when heated, then evaporate to reduce the initial volume by 2 times (solution temperature 125 ° C). A mixture of an aqueous solution of ammonia of 25% concentration and crystalline urea is prepared separately at the rate of 85 g per 1 liter of an aqueous solution of ammonia of 25% concentration. The resulting solution of chlorides or sulfates of the required cations (yttrium, aluminum and rare-earth metals) is sprayed into a mixture of an aqueous solution of ammonia of 25% concentration and crystalline urea at a rate of 85 g per 1 liter of an aqueous solution of ammonia of 25% concentration, cooled to 0 ° C. The precipitate obtained is decanted in deionized water to pH = 7. The resulting precursor is squeezed on a Buchner funnel and washed again on a Buchner funnel 2-3 times with high-purity acetone. The wet cake is dried in a vacuum oven at a temperature of 60-80 ° C. As a result of calcination at 1000 ° C of such a precursor, the target product (cubic yttrium aluminum garnet) contains 96.8 mass. % (Y _1-x REE _x ) ₃ Al ₅ O ₁₂ , other phases such as (Y _1-x REE _x ) ₄ Al ₂ O ₉ (2.8 wt.%) And Y ₂ O ₃ (0.4 mass%). Such impurities (table, sample 3) degrade all the basic characteristics: transparency, refractive index, transmission region, laser generation.

Example 4. Prepare a stock solution of cations of salts of a given composition, based on the formula (Y _1-x REE _x ) ₃ Al ₅ O ₁₂ , by dissolving the chlorides or sulfates of the desired cations (yttrium, aluminum and rare-earth metals) in water when heated, then evaporate to reduce the initial volume by 2 times (solution temperature 125 ° C). Separately, a mixture of an aqueous solution of ammonia of 25% concentration and crystalline urea is prepared at a rate of 90 g per 1 liter of an aqueous solution of ammonia of 25% concentration. The resulting solution of chlorides or sulfates of the required cations (yttrium, aluminum and rare-earth metals) is sprayed into a mixture of an aqueous solution of ammonia of 25% concentration and crystalline urea at the rate of 90 g per 1 liter of an aqueous solution of ammonia of 25% concentration, cooled to 0 ° C. The precipitate obtained is decanted in deionized water to pH = 7. The resulting precursor is squeezed on a Buchner funnel and washed again on a Buchner funnel 2-3 times with high-purity acetone. The wet cake is dried in a vacuum oven at a temperature of 60-80 ° C. As a result of calcination at 1000 ° C of such a precursor, the product (cubic yttrium aluminum garnet) contains 100 mass. % (Y _1-x REE _x ) ₃ Al ₅ O ₁₂ other phases are not detected (table 1, sample 4). Such samples have good quality: transparency in the visible range at the level of 70-75%, the refractive index is 1.8169 at 1064 nm, the transmittance in the infrared region of the spectrum is 0.7-5.5 μm at least 95%, the transmission region is near 1 micron (laser generation region) is equal to the theoretical limit.

Example 5. Prepare a stock solution of cations of salts of a given composition, based on the formula (Y _1-x REE _x ) ₃ Al ₅ O ₁₂ , by dissolving the chlorides or sulfates of the desired cations (yttrium, aluminum and rare-earth metals) in water when heated, then evaporate to reduce the initial volume by 2 times (solution temperature 125 ° C). Separately, a mixture of an aqueous solution of ammonia of 25% concentration and crystalline urea is prepared at the rate of 100 g per 1 liter of an aqueous solution of ammonia of 25% concentration. The resulting solution of chlorides or sulfates of the required cations (yttrium, aluminum and rare-earth metals) is sprayed into a mixture of an aqueous solution of ammonia of 25% concentration and crystalline urea at the rate of 100 g per 1 liter of an aqueous solution of ammonia of 25% concentration, cooled to 0 ° C. The precipitate obtained is decanted in deionized water to pH = 7. The resulting precursor is squeezed on a Buchner funnel and washed again on a Buchner funnel 2-3 times with high-purity acetone. The wet cake is dried in a vacuum oven at a temperature of 60-80 ° C. As a result of calcination at 1000 ° C of such a precursor, the product (cubic yttrium aluminum garnet) contains 100 mass. % (Y _1-x REE _x ) ₃ Al ₅ O ₁₂ , other phases are not detected (table 1, sample 5). Such samples have good quality: transparency in the visible range at the level of 80-85%, the refractive index is 1.8169 at 1064 nm, the transmittance in the infrared region of the spectrum is 0.7-5.5 μm at least 95%, the transmission region is near 1 micron (laser generation region) is equal to the theoretical limit.

Thus, the claimed method for producing highly stoichiometric nanoscale precursor powders is quite simple, as a result of its use, aluminum cations are not washed out, other impurity phases disappear, which sharply worsen all the main characteristics: transparency, refractive index, transmission region, and laser generation.

A comparative analysis of the claimed invention showed that the set of essential features of the claimed method for producing highly stoichiometric nanoscale precursor powders is not known from the prior art and meets the patentability condition “Novelty”.

In the prior art there were no signs that coincided with the distinguishing features of the claimed invention and affecting the achievement of the claimed technical result, therefore, the claimed invention meets the patentability condition "inventive step".

The above information confirms the possibility of using the claimed method to obtain highly stoichiometric nanoscale precursor powders based on yttrium-aluminum garnet with rare earth oxides, can be used in the chemical industry and therefore meets the patentability condition “industrial applicability”.

Claims (5)

1. A method of producing highly stoichiometric nanosized precursor powders based on yttrium aluminum garnet with rare earth oxides, including preparing a mother liquor of salts, evaporating to a concentrated state and spraying in an aqueous solution of ammonia, decanting in deionized water, filtering, subsequent drying and grinding, with a precipitant contains 90-100 g of crystalline urea per 1 liter of an aqueous solution of ammonia of 25% concentration. 2. The method according to p. 1, characterized in that the spraying is carried out in a mixture of an aqueous solution of ammonia of 25% concentration and crystalline urea at the rate of 90-100 g per 1 liter of an aqueous solution of ammonia of 25% concentration, cooled to 0 ° C. 3. The method according to p. 1, characterized in that the precipitate obtained is decanted in deionized water to pH = 7. 4. The method according to p. 1, characterized in that the resulting precursor is squeezed on a Buchner funnel and washed again on a Buchner funnel 2-3 times with high-purity acetone. 5. The method according to p. 1, characterized in that the wet cake is dried in a vacuum oven at a temperature of 60-80 ° C and, as a result of calcination at 1000 ° C of such a precursor, a 100% product is obtained: cubic yttrium aluminum garnet.