67 results about "Fluoride salt" patented technology

The invention relates to a negative electrode slurry and a preparation method thereof, a negative plate and a lithium ion battery, the negative electrode slurry mainly comprises a negative electrode active material, a binder composition, a conductive agent and a negative electrode additive, the mass ratio of the binder composition to the negative electrode additive is 2.0-2.4: 1.0-2.0, the binder composition comprises a component A, a component B and a component C, the component A is a fluorine-containing polymer, the component C is a fluorine-containing polymer, and the component B is a fluorine-containing polymer. The component B comprises a carboxylic acid compound, the component C is carboxymethyl cellulose salt, the negative electrode additive is alkali metal fluoride salt and / or alkaline earth metal fluoride salt, the pH value of the negative electrode slurry is 6.5-7.5, and the viscosity of the negative electrode slurry is 1000-4000 mpas. The negative electrode slurry disclosed by the invention has good dispersity and stability, and the prepared negative electrode plate can effectively relieve volume expansion of silicon, so that the rate capability, the cycling stability, the coulombic efficiency and the battery safety of the lithium ion battery can be effectively improved, and the consistency of the lithium ion battery is improved.

The application discloses a preparation method of an aluminum shielding tape surface conductive self-repairing coating. First, a clean aluminum shielding tape surface is obtained through an in-situ reduction / etching pretreatment method based on an aluminum salt / fluoride salt compound solution; second, a conductive / self-repairing dual-effect enhancer is prepared and introduced into a conductive / self-repairing coating synthesized by polyether amine, diisocyanate, a multiple active amine compound, p-xylene glycol and aniline; finally, the solid content of the coating is adjusted and sprayed on the clean aluminum shielding tape surface to obtain the conductive self-repairing coating. The application converts the Al2O3 film on the aluminum surface into a new substance Al, simultaneously constructs a regular porous structure, increases the bonding strength of the film layer, improves the adaptability and self-repairing efficiency of the coating in cable manufacturing and subsequent operation through the construction of a coating with multiple dynamic hydrogen bonds and imine bond synergistic effect, and realizes good conductive enhancement effect and rapid thermal self-repairing purpose of the coating by using isocyanate modified carbon nanotubes as the enhancer.

The utility model relates to the technical field of electrolytic bath blanking and filtering, and particularly discloses an electrolytic bath fluoride salt blanking port filtering device which comprises a feeding port, support legs are fixedly installed on the outer surface of the feeding port, the support legs are designed in a stacking mode and located on the inner side of the feeding port, an installation frame is inserted into the feeding port in a sliding mode, and the installation frame is connected with the feeding port in a sliding mode. And a filter screen is placed on the outer surface of the mounting frame in a clamped mode, the filter screen and the mounting frame are obliquely designed, and the mounting frame and the feeding opening are concentrically designed. According to the filter device for the fluoride salt feed opening of the electrolytic cell, fluoride salt added into the feed opening through a crown block can be filtered through the filter screen, and the filter screen can also filter impurities falling into the feed opening daily when the feed opening is not sealed; impurities in fluoride salt and impurities accidentally falling into the feeding port in daily use cannot enter the material box, and the impurities cannot enter the inside of the electrolytic bath to affect operation.

To provide a new method for producing a fluorinated organic compound in which removal or separation of an auxiliary is easy and which is advantageous in production cost.SOLUTION: A compound represented by the following formula (1): wherein R1, R2 and n are as defined in the description. The method comprises reacting the compound represented by the formula (1) with (A) at least one fluorine source selected from hydrogen fluoride, a hydrogen fluoride salt and a fluoride salt, (B) at least one iodine source selected from iodine and ammonium iodide, and (C) a compound having at least one fluorinated quaternary nitrogen atom in the molecule. A step of difluorinating the compound represented by the formula (1), wherein the amount of the iodine source (B) used is less than 1.0 mol per 1 mol of the compound represented by the formula (1).SELECTED DRAWING: None

The present application relates to waste residue recycling, and provides a system for extracting valuable lithium elements from aluminum electrolysis solid waste water treatment residue, which comprises a ball milling system, a slurry preparation system, an alkali leaching system, an acid leaching system, a fluoride salt directional conversion system, a impurity removal system and a post-treatment system connected in sequence; the alkali leaching system is connected with the fluoride salt directional conversion system. The system for extracting valuable lithium elements from aluminum electrolysis solid waste water treatment residue can efficiently extract valuable lithium elements in the water treatment residue, and significantly improves the economic benefits of harmless disposal and comprehensive utilization of aluminum electrolysis overhaul residue and carbon residue.

This invention discloses a method for the green co-processing of lithium slag and carbonaceous solid waste, relating to the field of slag treatment technology. The method includes: ball milling and mixing lithium slag, carbonaceous solid waste, and magnesium powder to obtain a reaction precursor; heating the reaction precursor under a protective atmosphere and negative pressure to produce solid products and flue gas containing beryllium, thallium, and fluorine; first, absorbing the flue gas containing beryllium, thallium, and fluorine with acid to obtain a beryllium-thallium acid washing solution; then absorbing the remaining fluorine-containing acidic tail gas with alkali to obtain a fluoride salt solution; mixing the solid product with the alkali solution, stirring, heating, washing to neutrality, and drying to obtain a porous material. This method practices the concept of "treating waste with waste," simultaneously solving the problems of gypsum decomposition, detoxification and fixation of toxic components, tail gas purification, and resource utilization through co-processing, achieving deep harmlessness of lithium slag, and significantly improving resource utilization and economic benefits.

The application provides a trivalent chromium passivation solution for maintaining the original color of aluminum alloy, which is prepared from basic chromium sulfate, zirconium salt, fluoride salt, corrosion inhibitor, organic acid complexing agent and water. The application also provides a preparation method of the trivalent chromium passivation solution for maintaining the original color of aluminum alloy, which comprises the following steps: heating water to 75-85 DEG C, then adding basic chromium sulfate, stirring while adding until completely dissolved, then adding zirconium salt, fluoride salt, corrosion inhibitor, organic acid complexing agent, silane coupling agent, water-soluble resin and nano silicon dioxide in sequence, and stirring for 1-2 h; using a pH regulator to adjust the pH value to 3.8-4.2, and the trivalent chromium passivation solution for maintaining the original color of aluminum alloy is obtained. The application also provides a passivation method for maintaining the original color of aluminum alloy. The application has the advantages of saving raw material cost, simple preparation method, and the like, and the passivated aluminum alloy part has a dense and uniform passivation film, the appearance color is maintained as the original color, the corrosion resistance exceeds 300 hours after neutral salt spray test, and the corrosion resistance is good.

A process for recovering lithium from waste lithium-ion batteries, or parts thereof, is disclosed. The process comprises the steps of: (a) providing a particulate material containing a transition metal compound and / or a transition metal, wherein the transition metal is selected from the group consisting of Mn, Ni, and Co, and wherein, furthermore, at least a fraction of said Ni and / or Co, if present, is in an oxidation state lower than +2 and at least a fraction of said Mn, if present, is manganese(II) oxide; wherein the particulate material further contains a lithium salt and a fluoride salt, and wherein the particulate material optionally contains calcium provided that the element ratio between calcium and fluorine is 1.7 or less or zero; (b) treating the material provided in step (a) with a polar solvent and an alkaline earth hydroxide; and (c) separating the solids from the liquid, optionally followed by washing the solid residue with a polar solvent, such as water, provides satisfactory separation of high-purity lithium and recovery of valuable transition metals.

The invention belongs to the technical field of fluosilicic acid utilization, and relates to a potassium fluosilicate decomposition method and application of the potassium fluosilicate decomposition method in preparation of hydrogen fluoride from fluosilicic acid. The method comprises the following steps: firstly, mixing an auxiliary agent with ammonia water, then mixing with potassium fluosilicate to form a decomposition system, adjusting the temperature of the decomposition system to 20-70 DEG C, stirring the decomposition system, simultaneously applying ultrasonic waves, and reacting for 5-10 hours to realize decomposition of potassium fluosilicate. In addition, solid potassium fluosilicate is obtained by adding soluble potassium salt into fluosilicic acid; the potassium fluosilicate is decomposed to obtain a fluoride salt solution, the fluoride salt solution is heated to expel ammonia and then reacts with fluosilicic acid to obtain an ammonium fluoride solution, the ammonium fluoride solution reacts with soluble calcium salt to obtain calcium fluoride solid, and the calcium fluoride solid reacts with concentrated sulfuric acid to obtain hydrogen fluoride. The potassium fluosilicate decomposition method can solve the problem that reaction raw materials are wrapped by reaction products, the raw material utilization rate and the product yield are remarkably improved, and the potassium fluosilicate decomposition method can shorten the technological process and reduce the production cost when applied to preparation of hydrogen fluoride from fluosilicic acid.

The invention relates to the technical field of dangerous solid waste treatment and resource utilization, in particular to an aluminum electrolysis overhaul slag fluoride enhanced leaching and resource recycling method. Comprising the following steps: adding pretreated overhaul slag into a complexing reaction solution of boric acid containing a dispersing agent and gluconate, and pulping; sealing the system, heating, and implementing pulse type micro-negative pressure degassing operation in which vacuumizing and normal pressure recovery are alternated during constant-temperature leaching; after the reaction is finished, carrying out thermal-state solid-liquid separation and tailing washing, and merging to obtain clear filtrate; crystal seeds are added into the filtrate, an aluminum source solution is dropwise added, the pH value is increased, solid-liquid separation is performed after constant-temperature curing, and synthetic cryolite is obtained; and supplementing the pH buffer agent to the clear liquid and then circularly returning to the liquid preparation process. According to the method, fluorine and aluminum are cooperatively extracted under the weak acid condition, generation of silicic acid gel is inhibited, equipment corrosion is reduced, mass transfer in pores is enhanced in combination with micro-negative pressure operation, and low-energy-consumption recovery of fluoride salt and closed-loop circulation of a working solution are achieved through pH regulation and control.

This invention discloses a method for preparing a TiB2 coating that inhibits particle agglomeration during electrophoretic deposition, comprising the following steps: First, a fluoride salt mixture is prepared and divided into two parts. One part of the fluoride salt is mixed with boron powder and titanium dioxide powder, heated to form a molten salt, and the upper layer of molten salt is extracted. After rapid cooling, crushing, and grinding, TiB2-fluoride salt composite powder is obtained. Then, the other part of the fluoride salt is heated to form a base molten salt, and the TiB2-fluoride salt composite powder is added to the base molten salt. Electrophoretic deposition is then performed using a ring-shaped graphite anode and a cathode to be deposited. This method prepares highly dispersed TiB2-fluoride salt composite powder through in-situ synthesis, and then uses a ring-shaped anode to reduce the probability of TiB2 particle agglomeration during electrophoresis, effectively inhibiting particle agglomeration and improving the TiB2 electrophoretic deposition efficiency.

The invention discloses a treatment system and process for fluorine-containing gas. The treatment system comprises a reaction unit, the reaction unit comprises at least two reactors which are connected in series to provide a space for catalytic decomposition and chemical adsorption of fluorine-containing organic matters, and the multiple reactors are vertically arranged; the gas inlet unit is used for selectively conveying fluorine-containing gas and hydrogen chloride to the reactor; the discharging unit is used for receiving the metal fluoride discharged from the reactor at the lowermost end; the feeding unit is used for conveying a catalyst to the reactor at the uppermost end; and the tail gas treatment unit is used for receiving gas discharged from the reactor. According to the technical scheme, the requirement that the catalyst is frequently replaced during continuous reaction is met, and on the basis that fluorine-containing organic matter in gas is removed through catalytic decomposition, chemical adsorption is further carried out, and a fluoride salt product with a high additional value is formed.

Disclosed herein is an aqueous treatment composition comprising: an acid, such as a fluorinated metal acid; and a fluoride salt. Further disclosed is a pretreatment composition comprising an acid, a metal source, a free fluorine compound source, and an aqueous medium. Methods of treating metal substrates, treated metal substrates, and kits are also disclosed.

A method for preparing a pentafluorosulfenyl aryl compound is disclosed. The method comprises reacting an aryl thioate, aryl thiol, or diaryl disulfide with iodine pentafluoride in the presence or absence of one or more additives to form an aryl sulfenyl pentafluoride, wherein the additive is selected from the group consisting of a fluoride salt, a non-fluoride salt, and an unsaturated organic compound.

The application provides an aluminum-scandium intermediate alloy and a preparation method thereof. The preparation method of the aluminum-scandium intermediate alloy comprises the following steps: mixing a composite fluoride salt molten liquid with a scandium source to perform first melting treatment, to obtain a first molten liquid; mixing the first molten liquid with an aluminum source to perform second melting treatment, to obtain a second molten liquid; mixing a composite chloride salt in at least three batches with the second molten liquid to perform third melting treatment, to obtain a third molten liquid; after slag removal treatment of the third molten liquid, calcination, smelting and cooling treatment are performed, to obtain the aluminum-scandium intermediate alloy. The preparation method of the aluminum-scandium intermediate alloy can effectively control the reaction process in a non-vacuum environment, reduce aluminum liquid oxidation and scandium element burning loss, improve product purity, and obtain an intermediate alloy with uniform scandium element distribution and high purity.

The invention discloses a method for recovering triethylamine in a preparation process of bis (fluorosulfonyl) imide triethylamine salt, which comprises the following steps: (a) taking sulfuryl fluoride, ammonia gas and triethylamine as raw materials, and reacting in an organic solvent to obtain a reaction solution containing bis (fluorosulfonyl) imide triethylamine salt and triethylamine hydrofluoride; (b) adding a phase transfer catalyst and an inorganic alkaline substance, and carrying out heat preservation reaction; (c) filtering to obtain solid fluoride salt and filtrate; and (d) carrying out vacuum evaporation concentration on the filtrate to obtain a concentrate and a triethylamine-containing recovered solvent, and using the triethylamine-containing recovered solvent for the next batch of reaction. According to the method, under the action of the phase transfer catalyst, the added inorganic alkaline substance reacts with the triethylamine hydrofluoride to generate the solid fluoride salt and dissociate the triethylamine, and the triethylamine can be recovered through vacuum evaporation and concentration, so that the method is simple to operate and convenient for industrial implementation, the triethylamine recovery cost is greatly reduced, and the method is suitable for industrial production. Meanwhile, the wastewater treatment difficulty is also reduced.

In a method for removing magnesium from molten aluminum according to the present invention, molten aluminum containing magnesium is produced from an aluminum raw material, and at least a portion of the magnesium in the molten aluminum is removed from the molten aluminum by using a flux. The flux is composed of fluoride salts. The melting point of the flux is 550°C or higher and below the liquidus temperature of the aluminum raw material. The flux may be a mixture of two or more types of fluoride salts.

The present application relates to the technical field of manganese additive, in particular to a kind of high and stable manganese additive of fast melting actual yield, including material and processing steps, material includes the following contents: manganese powder: 75-90%; Aluminum powder or fluoride salt: 7-22%; Surface lubricant: 0.5%-1.5%; Binder: 1%-3%, processing steps: S1, electrolysis: electrolytic manganese metal is broken under nitrogen protection and is screened into-200 mesh metal powder;S2, screening: fluxing agent fluoride salt or aluminum powder is broken or screened and-200 mesh powder of granularity specification is selected;S3, granulation: 75-90% of-200 mesh manganese powder, 7-22% of-200 mesh aluminum powder or fluoride salt, 1% of surface lubricant, 2% of binder.The beneficial effects of the present application increase the specific surface area in contact with aluminum liquid, rapidly contact with aluminum liquid after being put into aluminum liquid, and the large particles of granulated metal mixed powder rapidly disperse, respectively in suspended state, to make metal and aluminum liquid rapidly react and fuse with the help of fluxing agent, avoid the on-site of smelting long burning loss actual yield, so as to form the aluminum alloy of short smelting time, element content accurate and stable.

The invention relates to the technical field of building materials, and discloses an anti-crack high-performance concrete and a preparation method thereof, the anti-crack high-performance concrete comprises an energy synergistic long-acting micro-expanding agent formed by light calcined magnesia modified by a nano copper oxide catalyst; the multi-signal response type self-repairing agent is composed of anhydrous metastable state aluminosilicate glass body powder and slow release type fluoride salt particles. The preparation method comprises the following steps: mechanically co-grinding the two functional components and a part of the cementing material to obtain a functional master batch, and mixing the functional master batch with the remaining materials. Through the synergistic effect of the functional components and the unique preparation process, the drying shrinkage of the concrete is effectively inhibited, and the mechanical property is improved. When cracks are generated, the self-repairing system can be triggered by signals such as moisture to react with the micro-expansive agent in a synergistic manner, and a compact product is generated to effectively block the cracks, so that the durability and reliability of the concrete are remarkably improved, and the technical problem of cracking of concrete materials is solved.

The utility model relates to the field of nuclear energy and is intended for the purification of circulating fluoride salt melts in molten salt reactor installations, including those implementing the thorium fuel cycle. The method includes taking a portion of the circulating melt from the main circulation circuit of the reactor, directing said portion of the melt through a bypass line into a sorption-filtration module, passing the melt through a filter layer and returning the purified melt back to the circulation circuit. Filtration is carried out through a sorption-filtration material based on modified diatomite with a porosity of 60–85% and a pore size of 5–200 µm, formed as granules, porous blocks, or multilayer filtration cassettes. The technical result consists of increasing the purification efficiency of the circulating fluoride salt melt due to the simultaneous mechanical retention of solid particles and the sorption binding of colloidal impurities. The utility model was developed within the framework of the implementation of the scientific and technical program IRN BR24993225 for program-targeted financing of the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan for 2024–2026.

This invention relates to the field of alloy additives, and discloses a multifunctional multi-alloy element additive, its preparation method, and its application. The alloy additive comprises multi-alloy powder, flux, and binder. The multi-alloy powder includes at least four of the following: manganese, iron, magnesium, silicon, chromium, nickel, and titanium, and is a multi-particle-size mixture. The flux is a mixture of ferrosilicon alloy powder / ferroaluminum alloy powder and flux, and the flux is a fluoride salt or calcium-based flux. This invention overcomes the limitations of traditional additives that are only suitable for a single industry. In aluminum alloy smelting, it achieves a complete melting time ≤5 min, alloy element recovery rate ≥96.5%, and composition deviation ≤±0.25%. In steel smelting, it achieves a complete melting time ≤3 min, alloy element recovery rate ≥97.2%, and composition deviation ≤±0.3%. Simultaneously, it significantly improves the uniformity of composition and melting distribution, reduces oxidation loss and component segregation, and greatly improves the consistency of mechanical properties between aluminum alloys and steel products. It can be stably applied in aerospace, rail transportation, and high-end equipment manufacturing fields.

An apparatus for purifying high-purity phosphorus trifluoride according to one embodiment of the present invention comprises: a phosphorus trifluoride production unit including a reactor in which a phosphorus chloride compound solution and a metal fluoride salt react, and a purge device for vacuum-purging the reactor; a first freezing unit for cooling a phosphorus trifluoride mixed gas obtained from the phosphorus trifluoride production unit to remove unreacted materials contained in the phosphorus trifluoride mixed gas; and a second freezing unit for cooling the phosphorus trifluoride mixed gas obtained from the first freezing unit with liquid nitrogen to remove purge gas and hydrogen chloride (HCl).

The utility model discloses a fluoride salt charging vehicle for an electrolytic aluminum factory, and particularly relates to the technical field of charging vehicles, the fluoride salt charging vehicle comprises a first vehicle body, a second vehicle body is arranged on one side of the first vehicle body, and a crushing and conveying assembly is arranged at the top of the second vehicle body. The crushing and conveying assembly is arranged, a hollow flow guide frame drives a plurality of first crushing plates and second crushing plates to rotate when rotating, the second crushing plates crush large material blocks in a gathering frame when selecting, and crushing rods perform secondary crushing on the crushed material blocks when rotating, so that the situation that the material blocks are large and block the device is effectively avoided, and the crushing efficiency is improved. Air flow flows between the gathering frame and the gathering cover, small materials generated by crushing are prevented from being stacked on the inner wall of the gathering frame, the crushed raw materials can also be discharged through the discharging pipe, the materials are conveyed through rotation of the conveying auger, and the poor crushing effect caused by too many materials in the gathering cover is effectively avoided.

The present invention relates to a process of making a corrosion resistant, aluminium-deposited nickel-based superalloy super alloy for fission microstructures. The alloy comprises a nickel-based substrate (10) containing nickel, chromium, molybdenum, and titanium, with an aluminium layer (20) deposited on the substrate using vacuum plasma deposition. The substrate contains 80-88% nickel, 4-7% chromium, 6-9% molybdenum, and 1-3% titanium by weight. The aluminium layer have a thickness between 50-200µm, and acts as a barrier against fluoride salt attacks, reducing degradation rates and ensuring better structural integrity of the fission microstructure. The aluminium-deposited nickel-based superalloy can be used in various components of fission microstructures, including fuel cladding, heat exchangers, and reactor vessels, to improve the efficiency, longevity, and safety in nuclear environments.

This invention belongs to the field of inorganic fine chemical and high-end material preparation technology, and particularly relates to a method for preparing high-purity fluoride salts by deeply removing impurities and obtaining specific crystal forms through an innovative process. This invention achieves the preparation of high-purity crystalline fluoride salts through a synergistic technology of "front-end chemical precipitation for impurity removal - process complexation stabilization - back-end membrane separation coupled aging".

This utility model relates to the field of prebaked aluminum electrolytic cell technology, specifically a fluoride salt batching device for a prebaked aluminum electrolytic cell. It includes a mounting bracket, with a hydraulic cylinder and a storage silo mounted on top of the bracket. A drive motor, a mixing silo, a second drive motor, and a stirring rod are mounted on the outside of the mounting bracket. A third drive motor is mounted on the outside of the mixing silo, and its output is connected to a feeding rod. A discharge port is installed at the bottom of the mixing silo, and a servo motor is mounted at the top, with its output connected to a transmission rod. A weighing hopper is mounted on the transmission rod, and a weighing scale is installed at the bottom of the weighing hopper. After mixing, drive motors one and two are turned off, while drive motor three continues to operate. The mixing silo remains tilted, and the solenoid valve is opened to discharge the raw material through the discharge port. Drive motor three drives the feeding rod to rotate, preventing the raw material from clogging the discharge port, thus completing the batching process. This method ensures a fast discharge speed.

A phosphorous compound such as STMP is used as a cross-linking agent while making a starch nanoparticle in an emulsion process. Negative charge of the nanoparticle is reduced or reversed by adding cations and / or cationizing the starch optionally while forming the nanoparticles. Anionic active agents, such as fluoride or fluorescein, are optionally incorporated into the nanoparticle during the formation process. For example, a fluoride salt can also be used, which promotes the crosslinking reaction while also providing fluoride in the nanoparticle. The retention of both calcium and fluoride in the nanoparticle is improved when both salts are used. Alternatively, the nanoparticle may be used without added calcium and / or fluoride. The nanoparticles may be useful for tooth remineralization, the treatment of dentinal hypersensitivity, to treat caries, or as a diagnostic agent to locate carious lesions.

The invention relates to an oil and gas field blocking remover and a preparation method thereof, and belongs to the technical field of oil and gas development. The blocking remover comprises the following components in percentage by mass: 15%-25% of a polydentate chelating acid compound, 5%-8% of fluoride salt, 2%-5% of a surfactant compound, 1%-3% of a corrosion inhibitor, 2%-4% of a mutual solvent, 0.5%-1% of a dispersing agent and the balance of water, the polydentate chelating acid compound comprises amino trimethylene phosphonic acid and 1-hydroxyethylidene-1, 1-diphosphonic acid; and the surfactant compound comprises a quaternary ammonium salt type surfactant and a PO-EO block copolymer. The blocking remover provided by the invention can realize a good blocking removal effect on inorganic-organic composite blocking substances, is low in corrosion rate to a tubular column, reduces unnecessary damage to the tubular column, and has a wide market prospect. The invention further provides a preparation method of the blocking remover, and the preparation method is simple in process, low in requirements on environment and equipment and suitable for industrial application.

The invention belongs to the technical field of electronic materials, and discloses a magnesium-strontium double-doped calcium fluoride crystal and a preparation method and application thereof.The method comprises the steps that firstly, disodium ethylene diamine tetraacetate is chelated with calcium and magnesium ions, and the calcium and magnesium ions and villiaumite are subjected to a coordination exchange reaction to prepare a magnesium-doped calcium fluoride microsphere precursor; regulating and controlling hydrolysis of 3-aminopropyltriethoxysilane through an absolute ethyl alcohol-deionized water mixed solvent, and realizing uniform anchoring and deposition of strontium ions by virtue of an interface connection effect of the 3-aminopropyltriethoxysilane, so as to construct a magnesium-strontium double-doped precursor with a core-shell structure; carrying out hot pressed sintering in a CF4 / Ar mixed atmosphere to obtain a high-density polycrystalline blank; and finally, finishing crystal oriented growth by adopting a Bridgman-Stockbarger method. Through the synergistic effect of the components in the whole process, gradient uniform doping of magnesium and strontium ions is achieved, lattice distortion is effectively eliminated, the optical uniformity, the anti-laser-damage threshold value and the mechanical stability of the crystal are improved, and the prepared crystal can be widely applied to manufacturing of special electronic materials such as semiconductor wafers and the like and has good industrialization prospects.

Provided is a novel method for producing a fluorinated organic compound that facilitates removal or separation of an auxiliary agent and that is advantageous in terms of production costs. The production method is a method for producing a difluoride which is a compound represented by formula (1) (in the formula, R1, R2, and n have the same definitions as the symbols described in the specification). The method involves a step for reacting the compound represented by formula (1) with (A) at least one fluorine source selected from hydrogen fluoride, hydrogen fluoride salts, and fluoride salts, (B) at least one iodine source selected from iodine and ammonium iodide, and (C) a compound having at least one fluorinated quaternary nitrogen atom in the molecule to difluorinate the compound represented by formula (1), wherein the amount of the iodine source (B) used is less than 1.0 mol with respect to 1 mol of the compound represented by formula (1).