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• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
  • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
  • C09K11/61—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing fluorine, chlorine, bromine, iodine or unspecified halogen elements
  • C09K11/617—Silicates
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
  • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
  • C09K11/61—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing fluorine, chlorine, bromine, iodine or unspecified halogen elements
  • C09K11/615—Halogenides
  • C09K11/616—Halogenides with alkali or alkaline earth metals
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y40/00—Manufacture or treatment of nanostructures
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
  • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Definitions

• the present invention relates to a sol-gel method for synthesizing a luminescent material of general formula: AxByFz: Mn.
• A represents an element belonging to one of the following groups of the Periodic Table of Elements also known as the Mendeleyev Table: Groups 1, 2, 4, NR 4 or a combination of elements, with the proviso that R is hydrogen or an alkyl chain, alone or in combination.
• B represents an element belonging to one of the groups 5, 6, 13, 14, x is a value greater than zero and less than or equal to five, y is a value greater than zero and less than or equal to two and z is greater than or equal to at five and less than or equal to seven.
• Luminescent materials that is to say materials that under the action of an excitation emit light
• luminescent materials are used in the field of lighting, lasers, medical imaging among others.
• luminescent materials are used in the production of Electro-Luminescent Diodes or LEDs according to the acronym generally used.
• LEDs are increasingly present for so-called traditional lighting, replacing, for example, halogen or incandescent lamps.
• the white LEDs provide lighting similar to natural light.
• white LEDs are manufactured by combining a semiconductor emitting between 400 nm and 500 nm with a yellow / green phosphor emitting between 480 nm and 650 nm.
• CRI color rendering index
• the manufacture of white LEDs with high color rendering index, or CRI requires the addition of a red component enhancing the emission between 600 nm and 700 nm.
• the compounds of the family of nitrides doped with europium are a solution of choice. They characterized by intense red emission and thermal stability. However, these compounds remain expensive and difficult to produce.
• an emerging solution is the use of complex fluorinated compounds of the general formula AxByFz: Mn 4+ . These materials have a narrow emission range favorable to obtaining a high CRI and are less expensive because of the absence of rare earths in their composition.
• sol-gel type processes allow the production of low temperature luminescent materials, namely a temperature lower than that of conventional ceramization pathways.
• ceramization can be obtained at temperatures below 100 ° C.
• This type of process is based on an inorganic polymerization, starting from precursors in solution, which gives rise to an organometallic network precursor of the final solid.
• colloids are formed as well as polymeric gels. After drying and sintering, it is possible to obtain fibers, monoliths or powders.
• the matrix structure of these various processes is characterized by crystallographic sites easily incorporating rare earths. These sites are unsuitable for the reception of transition ions of electronic configuration d 3 , such as Cr 3+ or Mn 4+ .
• transition ions of electronic configuration d 3 such as Cr 3+ or Mn 4+ .
• the use of rare earths is disadvantageous in terms of costs.
• the invention aims more particularly at providing a sol-gel synthesis process, easy to implement, without organic source of fluorine, without hydrofluoric acid and without rare earths.
• metal reagents chosen from metal salts such as halides, nitrates, hydrides, amides, acetates, carbonates or alkoxides, with manganese, the mixture being carried out at pH ⁇ 8,
• step b) obtaining a solid precursor from the liquid precursor obtained in step a), by removing the solvent,
• step c) recovering the fluorescent crystalline powder obtained at the end of step c).
• such a method may comprise one or more of the following features:
• step a) the pH is maintained below 8 by the addition of an acid, chosen, without limitation, from carboxylic acids such as formic acid, acetic acid, propanoic acid, citric acid, tartaric acid, oxalic acid, among sulfonic acids such as benzene sulphonic acid, paratoluene sulphonic acid, among anhydrous acids, hydrochloric acid in solution in diethyl ether, in dioxane or in gaseous form.
• carboxylic acids such as formic acid, acetic acid, propanoic acid, citric acid, tartaric acid, oxalic acid, among sulfonic acids such as benzene sulphonic acid, paratoluene sulphonic acid, among anhydrous acids, hydrochloric acid in solution in diethyl ether, in dioxane or in gaseous form.
• step a) the pH is maintained below 8 by adding a carboxylic acid: acetic acid.
• step a) is carried out at a temperature of between 15 ° C. and the boiling point of the solvent used.
• step a) The liquid precursor obtained in step a) is, if necessary, stored for a subsequent implementation of step b).
• step b) The solid precursor obtained in step b) is, if necessary, stored for a subsequent implementation of step c).
• the metal reagents used in step a) are all chosen from alkoxides.
• the metal reagents used in step a) are mixtures of metal salts.
• Step c) is carried out at a temperature of between 100 ° C. and 1000 ° C. for at least 30 minutes.
• the fluorinated agent used in step c) to generate a fluorinated atmosphere is chosen from: F 2 , HF, BrF 3 , TbF 4 , XeF 2 , XeF 4 and XeF 6 , NH 4 F, NH 4 HF 2 , CoF 3 , SbF 3 , SbF 5 , ArF 3 , KrF, BrF 5 , CIF, CIF 3 and CIF 5 , HF0 3 S, AuF 3 , IF 5 , MnF 3 and MnF 4 , NOF and N0 2 F NF 3 , ClO 3 F, PtF 6 , SeF, SiF, AgF 2 , SF, SF 6 , KF, PbF 2 , ZnF 2 , SnF 2 , CdF 2 alone or in combination.
• the atmosphere contains at least 1% of fluorinated agent.
• step c) the fluorinated atmosphere is static or dynamic.
• step d At the end of step d), the particles obtained are reintroduced into a liquid precursor, in step a).
• the liquid precursor is chosen to ensure double luminescence, for magnetic properties or for other characteristics.
• FIG. 1 is a simplified diagram illustrating the different steps of the method according to one embodiment of the invention.
• transition metals in general and, more particularly, according to an advantageous embodiment of the invention, with, inter alia, manganese
• the invention is also applicable with, for example, chromium, iron or any other transition element of groups 3 to 12 of the periodic table of elements. It is conceivable that the use of this or that transition metal makes it possible to obtain luminescence in different spectral domains, therefore in different colors. In in all cases, luminescence is obtained by excitation of the transition element in a range from ultraviolet to infrared, followed by radiative deexcitation.
• the use of manganese as one of the metal reagents makes it possible to obtain a luminescence in the red, ie between 600 nm and 700 nm.
• the final fluorinated material is a compound of formulation: AxByFz: C m +
• small size refers to an alkyl chain having 1 to 4 carbon atoms.
• A, B, C are also simple or complex metal reagents.
• metals as for example Manganese, Chromium, Iron or any other transition element as salts of these metals or a mixture of these metals.
• metal reagents are known per se and are either produced in situ prior to the implementation of the process or are of commercial origin. In other words, the user gets them upstream from a supplier.
• metal alkoxides as metallic reagents makes it possible to produce a heteroatomic polymeric network in solution, when of step a), which subsequently promotes the formation of the desired final matrix.
• metal alkoxides it is possible to use other metal reagents than metal alkoxides, as mentioned above.
• a first step represented under the reference 1, the metal sources A, B and manganese are reacted together with alcohol.
• the alcohol or mixture of alcohols is chosen according to the metal reagents, in order to ensure optimal solubilization.
• the reaction is carried out, under a neutral atmosphere, in a stirred reactor and at a temperature between 15 ° C and the boiling point of the solvent and for a reaction time of between a few minutes and several hours.
• the optimal reaction time is close to 4h.
• Manganese unlike Rare Earths, is sensitive to pH. In basic medium, manganese can be oxidized by dissolved oxygen and form Mn0 2 . Such a property is known, it is also used in a method, called Winckler, dissolved oxygen assay.
• the reaction, during step a) must be carried out in a non-basic medium, namely in this case at a pH of less than 8.
• the pH is between 1 and 7, preferably close to 5.
• the reaction must take place in an anhydrous medium.
• an anhydrous acid advantageously chosen, in a nonlimiting manner, from carboxylic acids such as formic acid, acetic acid, propanoic acid, and the acid.
• carboxylic acids such as formic acid, acetic acid, propanoic acid, and the acid.
• acetic acid is used.
• a liquid precursor 2 is obtained at the conditions of normal temperature and pressure.
• step 1 can be performed at any time and / or place in relation to the rest of the process.
• the liquid precursor 2 can easily be stored, as illustrated by reference 3. It is thus possible to relocate the production of the liquid precursor 2.
• the conditions of storage and / or transport do not alter not the liquid precursor and the continuation of the process.
• the liquid precursor is a flammable product that must be stored away from light.
• the liquid precursor 2 is used from its production, either continuously or discontinuously.
• the second step of the process is then implemented, either from the liquid precursor 2 produced or from the stored liquid precursor 3.
• liquid precursor will be referenced 2 if it is used directly and referenced 3 if it is a previously stored liquid precursor.
• This step 4 makes it possible to obtain a solid precursor 5.
• the alcoholic solvent is eliminated.
• the alcohol is evaporated by heating at a temperature corresponding to the boiling temperature of the alcoholic solvent, this temperature having no effect on the other constituents of the liquid precursor.
• the solvent is removed by evaporation under reduced pressure, by dring spray, freeze drying or any other technique known per se.
• the object of this step 4 is to initiate and solidify a reaction intermediate containing the elements A, B and C.
• the parameters of step 4 are variable and depend on the solvent used and the removal method chosen. .
• the fluorine source is not yet present in the process, which makes it possible to safely handle, transport and store the various precursors, while managing the moment of incorporation of the fluorine source.
• the next step, illustrated by the arrows 7 or 70 depending on whether the solid precursor 5 is used immediately or whether it is a stored solid precursor 6, consists of a heat treatment which makes it possible to supply the fluorine in the form of atomic and / or molecular, to the solid precursor from its production, according to reference 5, or to the solid precursor stored, according to reference 6. It should be noted that the fluorine intake is carried out only in step 7, 70 and not before.
• step 7, 70 is carried out under a fluorinated atmosphere.
• fluorinating agent of: F 2 , HF, BrF 3 , TbF 4 , XeF 2 , XeF 6 , NH 4 F, CoF 3 , SbF 3 , ArF 3 , BrF 5 , CIF , CIF 3 , CIF 5 , HFO 3 S, AuF 3 , IF 5 , MnF 3 , MnF 4 , NOF, NO 2 F, Cl 3 F, PtF 6 , SeF 4 , AgF 2 , SF 4 .
• the heat treatment carried out during this step 7, 70 is carried out between 100 ° C. and 1000 ° C. for a duration of at least 30 minutes under a fluorinated atmosphere containing at least 1% of fluorine. Indeed, it is not necessary that the atmosphere is saturated with fluorine, the rest of the atmosphere may be a neutral gas such as nitrogen.
• K 2 SiF 6 Mn (IV) is synthesized from MnCl 2 , K metal and tetraethyl orthosilicate (TEOS).
• the solvent used is anhydrous ethanol.
• MnCl 2 (0.1713 g) is added a solution of K (3.6432 g).
• TEOS 9.3272 g is added to the previous solution.
• acetic acid (1.18 ml) is added in order to adjust the pH to 5.
• the salts are removed from the solution and the solution is evaporated. dried up.
• the precursor thus obtained is heat-treated at 500 ° C. under a flow of F 2 for 15 hours.
• Mn (IV) is synthesized from MnCl 2 , Na metal and tetraethyl orthotitanate (TEOT).
• the solvent used is anhydrous isopropanol.
• MnCl 2 (0.1817 g)
• Na 0.7268 g
• acetic acid 3.79 ml
• the salts are removed from the solution and the solution is evaporated at room temperature. dry.
• the precursor thus obtained is heat-treated at 500 ° C. under a flow of F 2 for 15 hours.
• Na 3 AIF 6 was synthesized from Na metal and aluminum isopropoxide.
• the solvent used is anhydrous methanol.
• To a solution of Na (1.6675 g) is added aluminum isopropoxide (4.9135 g).
• acetic acid (8.71 ml) was added to adjust the pH to 5.
• the solution was cooled to 25 ° C.
• the Na 2 TiF 6 : Mn (IV) powder obtained in Example 2 is dispersed in a molar ratio of 3: 1 to Na 2 TiF 6 : Mn (IV). The dispersion thus obtained is evaporated and then heat treated at 650 ° C. under a flow of F 2 for 3 hours.
• LiSrAIFe Cr (III) is synthesized from lithium ethoxide, strontium isopropoxide, chromium acetylacetonate and aluminum isopropoxide.
• the solvent used is anhydrous isopropanol.
• To a solution of lithium ethoxide (0.7171 g), strontium isopropoxide (2.6132 g) and chromium acetylacetonate (0.1336 g) is added aluminum isopropoxide (2.5408 g). After stirring for 30 minutes at reflux, acetic acid (3.18 ml) was added in order to adjust the pH to 5. After 6 hours of reflux, the solution was cooled to 25 ° C.
• Example 2 is dispersed the K 2 SiF 6 : Mn (IV) powder obtained in Example 1, in a molar ratio of 9 to 1 in K 2 SiF 6 : Mn (IV).
• the dispersion thus obtained is evaporated and then heat-treated at 600 ° C. under a flow of F 2 for 10 hours.
• the heat treatment is preferably carried out dynamically, that is to say under a stream of fluorinated gas. Alternatively, it is performed in a static manner: step 7, 70 then taking place in a closed volume, in a fluorinated atmosphere. At the end of step 7 or 70, depending on the origin of the solid precursor, 5 or 6, a crystalline powder 8 is obtained.
• the size of the particles obtained is a function of the nature of the solid precursor and the conditions of the treatment. 7. Generally, the size of the particles is close to 200 nm.
• the particles may be in the form of aggregates whose size is of the order of one micron. Such a particle size is particularly suitable for allowing the phosphor to be shaped and deposited, for example on an LED 9.
• the particle size it is possible to increase the particle size by depositing one or more additional layers. For this, it is sufficient to bring the solid particles 8 into contact with the liquid precursor 2 or 3 by dispersing them in the latter, and to carry out at least one other solvent removal step 4 followed by a step 7, 70 heat treatment.
• this additional cycle is performed on a mixture of liquid precursor 2 or 3 and 8 particles, so under conditions that are not necessarily the same as those of the initial step 7, 70. It is conceivable that the repetition of the cycle is carried out several times as much as necessary.
• the method also makes it possible to protect the powder from the aggressions of its immediate environment by depositing a passivation layer during this or these additional cycle (s).
• a passivation layer for example, by reintroducing the powder 8 in a liquid precursor 2 or 3 Na 3 AIF 6, also known as the synthetic cryolite, the particles are coated with a protective layer. It is also possible to deposit one or more layers on the particles conferring on the latter other characteristics, such as, without limitation, magnetic properties or a characteristic ensuring the identification and traceability of the final product.
• Such a method is therefore of flexible and easy use, which allows, safely, to produce different luminescent products.
• Such a method makes it possible, for the various steps of production of a solid precursor (step b) and of crystallization (step c), to use, respectively, liquid and solid precursors originating either directly from the preceding step or from a storage, 3 or 6, a mixture, in variable proportion, of precursors derived partly from storage and partly from the previous step. It is thus possible to regulate the production, in each of steps b) and c), adjusting if necessary the amount of precursors used from the precursors 3 or 6 stored.

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• 2015
  • 2015-11-13 FR FR1560857A patent/FR3043687B1/fr active Active
• 2016
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  • 2016-11-10 JP JP2018544432A patent/JP2019500312A/ja active Pending
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