Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F7/00—Compounds of aluminium
  • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
  • C01F7/16—Preparation of alkaline-earth metal aluminates or magnesium aluminates; Aluminium oxide or hydroxide therefrom
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F7/00—Compounds of aluminium
  • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2002/00—Crystal-structural characteristics
  • C01P2002/50—Solid solutions
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2002/00—Crystal-structural characteristics
  • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
  • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/01—Particle morphology depicted by an image
  • C01P2004/03—Particle morphology depicted by an image obtained by SEM
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/20—Particle morphology extending in two dimensions, e.g. plate-like
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/30—Particle morphology extending in three dimensions
  • C01P2004/32—Spheres
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/51—Particles with a specific particle size distribution
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/12—Surface area
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/16—Pore diameter
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/60—Optical properties, e.g. expressed in CIELAB-values

Definitions

• the present invention relates to a precursor compound of an alkaline earth aluminate, a crystalline compound of the alkaline earth aluminate type, processes for their preparation and the use as phosphor of the crystallized compound.
• Many manufactured products incorporate in their manufacture phosphors. These phosphors can emit light whose color and intensity are a function of the excitation they undergo. They are thus widely used for example in plasma-type display screens or in trichromatic lamps.
• this type of luminophores mention may be made of divalent europium doped barium and magnesium aluminate of formula BaMgAl 2 OO 7 : Eu 2+ (BAM). It is a luminophore that has particularly interesting properties because, in particular, it has an excitation spectrum covering the entire UV and VUV domain with a very high quantum yield and gives a emission color that is perfectly blue and saturated.
• the compound of the invention is an alkaline earth metal aluminate compound crystallized at least in part as a beta-type alumina and is characterized by having a composition corresponding to the formula: a (M 1 0) .b (Mg0) .c (Al 2 O 3 ) (1) in which M 1 denotes at least one alkaline earth and a, b and c are integers or non-verifying relationships: 0.25 ⁇ a ⁇ 4; 0 ⁇ b ⁇ 2 and 0.5 ⁇ c ⁇ 9; in that M 1 is partially substituted with europium and at least one other element belonging to the group of rare earths whose ionic radius is smaller than that of Eu 3+ and in that it is in the form of particles substantially whole and of average size not more than 6 ⁇ m.
• the invention also relates to a precursor of an alkaline earth aluminate, characterized in that it has a composition corresponding to the formula: a (M 1 0) .b (Mg0) .c (Al 2 O 3 ) (1) wherein M 1 denotes at least one alkaline earth and a, b and c are integers or non-verifying relationships:
• M 1 is partially substituted with europium and at least one other element belonging to the group of rare earths whose ionic radius is smaller than that of Eu 3+ and in that it is in the form of particles of average size of not more than 15 ⁇ m.
• the process for preparing the crystalline compound of the alkaline earth aluminate type mentioned above is, according to the invention, characterized in that it comprises the same steps as those described above and, in addition, a step in which the product from the first calcination is calcined again at a temperature sufficient to reveal the tridimite, beta, magnetoplombite or garnet type alumina structure and / or luminescence properties for said compound.
• the crystallized compounds of the invention have improved resistance to heat treatments and / or in operation. Under certain conditions one can even observe no degradation of their luminescence property after the heat treatment (baking) or in operation. Finally, at least under certain excitation conditions, in particular under UV or VUV, their luminescence, in itself and independently of its better resistance to degradation, may also be greater than those of the products of the prior art.
• FIG. 1 is an X-ray diagram of a precursor compound according to the invention
• FIG. 2 is an RX diagram of an aluminate obtained by calcination of a precursor compound according to the invention
• FIG. 3 is a scanning electron microscopy (SEM) photograph of a precursor compound of the invention
• FIG. 4 is a scanning electron microscopy (SEM) photo of an aluminate compound according to the invention.
• the invention relates to two types of products, one of which may in particular have luminescence properties, a compound which will be called in the following description "aluminate compound", the other which may be considered as a precursor of crystallized compounds of the invention.
• aluminate compound alkaline earth aluminate type, and especially as precursor of the aluminate compound of the invention, and which will be called in the following description "precursor compound” or "precursor”.
• the alkaline earth may be more particularly barium, calcium or strontium, the invention being more particularly applicable to the case where M 1 is barium and in the case where M 1 is the barium in combination with strontium in any proportion but which may be for example at most 30% strontium, this proportion being expressed by the atomic ratio in% Sr / (Ba + Sr).
• the element M 1 is partially substituted by at least two substituent elements. It is important to note here that the present description is made in the assumption that corresponds to the current knowledge of the Applicant, that is to say that the aforementioned substituent elements are indeed in substitution for M 1 but the description must not be interpreted in a limiting manner on the basis of that assumption. This implies that it would not depart from the present invention if the substituents described for the element M 1 were found to be in fact substituted for another constituent element than that assumed in the present description.
• the essential characteristic is the presence of the aforementioned elements and presented as substituents in the compound. As far as the nature of these substituents is concerned, one of these is europium.
• the other one or more substituents are selected from the group of rare earths whose ionic radius is lower than that of Eu 3+ .
• This group contains in fact rare earths of atomic number higher than that of europium and therefore the following elements: gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium. Yttrium and scandium belong to this group.
• the second substituent element is chosen from gadolinium, terbium, ytterbium or yttrium and, in particular, it may be ytterbium or ytterium and the combination of these. last two elements.
• the amounts of the substituents may vary, in known manner, in wide ranges.
• the minimum amount of substituents is that below which the substituents no longer produce an effect.
• the europium should preferably be present in an amount sufficient for this element to provide the compound with suitable luminescent properties.
• the amount of the second substituent is also fixed by the resistance threshold for heat treatments that it is desired to obtain. For the maximum values, it may be preferable to remain below the amount from which it is no longer possible to obtain compounds which are phasically pure, for example which are in the form of a pure beta-alumina.
• the quantity of europium and of the other element mentioned above may be at most 30%, this quantity being expressed by the atomic ratio (Eu + other element) / (M 1 + Eu + other element) in% . It can also be more particularly at least 1%. It may for example be between 5% and 20%, more particularly between 5% and 15%.
• the amount of the other substituent element is at most 50%, more particularly at most 30%, this quantity being expressed by the atomic ratio other element / Eu in %.
• This amount can be at least 1%, more particularly at least 2% and even more particularly at least 5%.
• the magnesium may also be partially substituted by at least one element chosen from zinc, manganese or cobalt.
• the aluminum may be partially substituted by at least one element selected from gallium, scandium, boron, germanium or silicon.
• the combustion chamber comprises a coaxial inner cylinder, thus defining inside thereof a central zone and an annular peripheral zone, presenting perforations situated for the most part towards the upper part of the apparatus.
• the chamber comprises at least six perforations distributed over at least one circle, but preferably on several circles spaced axially.
• the total area of the perforations located in the lower part of the chamber may be very small, of the order of 1/10 to 1/100 of the total surface area of the perforations of said coaxial inner cylinder.
• a fuel phase which may in particular be methane, is injected axially through the above-mentioned opening in the central zone at a speed of approximately 100 to 150 m / s.
• the last step of the process consists of calcining the product obtained after drying.
• the calcination temperature can be at least
• the duration of the calcination is chosen, again, sufficiently long to obtain the product in the desired crystallized form and according to the level of luminescence property required. For example, this time may be between 30 minutes and 10 hours, it may be more particularly between 1 and 3 hours, for example about 2 hours.
• An aluminate of the same morphology as the precursor compound of the invention can be obtained by calcining without flux or a product in the form of of platelets by calcining with a flux in the case of products with structure of alumina beta.
• a LECO CS 444 analyzer was used to simultaneously determine the total carbon and total sulfur content by a technique burns in an oxygen induction furnace and detection by an infrared system.
• the sample (standard or unknown) is introduced into a ceramic crucible in which a LECOCEL type accelerator and an IRON type flux are added (during the analysis of the unknown samples).
• the sample is melted at high temperature in the furnace, the flue gases are filtered on a metal grid and then pass through a series of reagents.
• the SO 2 is detected using a first infrared cell.
• the gases pass through a catalyst (platinized silica gel) that converts CO to CO 2 and SO 2 to SO 3 .
• a catalyst platinumized silica gel
• the latter is trapped by cellulose and using two infrared cells, the CO 2 is detected.
• a LECO TC-436 analyzer was used to determine the nitrogen content by a technique involving a Joule effect furnace melting. The nitrogen content is measured by thermal conductivity.
• the nitrogen is then detected by a cell with thermal conductivity.
• This example relates to the preparation of a luminophore of barium aluminate and magnesium of formula Ba 0 , 9 Euo , iMgAlioOi 7 .
• the raw materials used are a boehmite sol (specific surface of 265 rpm) at 0.157 mol of Al per 100 g of gel, a 99.5% barium nitrate, a 99% magnesium nitrate and a nitrate solution.
• 200 ml of boehmite sol ie 0.3 mol of Al) are prepared.
• the salt solution (150 mL) contains 7.0565 g of Ba (NO 3 ) 2 ; 7.9260 g of Mg (NO 3 ) 2 ; 2.2294 g of the solution of Eu (NO 3 ) 3 .
• the final volume is completed with water at 405 mL (ie 2% in
• the final pH after mixing the soil and the salt solution is 3.5.
• the suspension obtained is atomized in an atomizer of the type described in the European patent application 0007846 with a temperature of 240 0 C output.
• the dried powder is calcined at 900 ° C for 2 hours in air.
• the powder is calcined at 1500 ° C. for 2 hours under 3% hydrogenated argon.
• This example relates to the preparation of a phosphor of barium aluminate and magnesium of formula Bao, 89 Eu 0, iYo, oiMgAI 10 O 17 .
• the procedure is as in Example 1 but also using as additional raw material yttrium nitrate Y (NO 3 ) 3 introduced in stoichiometric amount.
• This example relates to the preparation of a luminophore of barium aluminate and magnesium of formula and Ba 0.89 Euo, iYbo , oiMgAlioOi 7 .
• the procedure is as in Example 1 but also using as additional raw material ytterbium nitrate Yb (NO 3 ) 3 introduced in stoichiometric amount.
• Luminescence was also measured for the product of Example 1 and that of Example 3 for excitation under VUV (173 nm). This luminescence is measured by the area under the emission spectrum curve between 380 nm and 650 nm. The value obtained for the product of Example 1 is 100 and it is 104 for that of Example 3. The product according to the invention thus has an improved luminescence under VUV excitation.
• the luminescence yields are measured from the emission spectrum of the products. This spectrum gives the emission intensity under excitation at 254 nm as a function of the wavelength values between 350 nm and 700 nm. A relative yield is measured that corresponds to the area of the spectrum curve and is set at a base 100 for the comparative product prior to the heat treatment.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Inorganic Chemistry (AREA)
• Luminescent Compositions (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
• Gas-Filled Discharge Tubes (AREA)
• Vessels And Coating Films For Discharge Lamps (AREA)

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• 2004
  • 2004-11-10 FR FR0411980A patent/FR2877663B1/fr not_active Expired - Fee Related
• 2005
  • 2005-11-04 CA CA002582688A patent/CA2582688A1/fr not_active Abandoned
  • 2005-11-04 KR KR1020077010503A patent/KR100844733B1/ko not_active IP Right Cessation
  • 2005-11-04 JP JP2007540671A patent/JP2008520523A/ja not_active Abandoned
  • 2005-11-04 MX MX2007005585A patent/MX2007005585A/es unknown
  • 2005-11-04 EP EP05814923A patent/EP1807483A1/fr not_active Withdrawn
  • 2005-11-04 US US11/666,517 patent/US20090140204A1/en not_active Abandoned
  • 2005-11-04 WO PCT/FR2005/002752 patent/WO2006051193A1/fr active Application Filing
  • 2005-11-04 CN CNA200580036042XA patent/CN101044224A/zh active Pending

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