WO2010064686A1 - Composé diélectrique et son procédé de fabrication - Google Patents

Composé diélectrique et son procédé de fabrication Download PDF

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WO2010064686A1
WO2010064686A1 PCT/JP2009/070323 JP2009070323W WO2010064686A1 WO 2010064686 A1 WO2010064686 A1 WO 2010064686A1 JP 2009070323 W JP2009070323 W JP 2009070323W WO 2010064686 A1 WO2010064686 A1 WO 2010064686A1
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compound
dielectric compound
dielectric
powder
firing
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Japanese (ja)
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達生 藤井
潤 高田
直 池田
真 中西
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国立大学法人岡山大学
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B19/00—Apparatus or processes specially adapted for manufacturing insulators or insulating bodies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
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    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G49/00—Compounds of iron
    • C01G49/0018—Mixed oxides or hydroxides
    • C01G49/0054—Mixed oxides or hydroxides containing one rare earth metal, yttrium or scandium
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    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/26—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on ferrites
    • C04B35/2675—Other ferrites containing rare earth metals, e.g. rare earth ferrite garnets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
    • H01B3/10—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances metallic oxides
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    • 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
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    • 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
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    • 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
    • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3224—Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/327—Iron group oxides, their mixed metal oxides, or oxide-forming salts thereof
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/327—Iron group oxides, their mixed metal oxides, or oxide-forming salts thereof
    • C04B2235/3272—Iron oxides or oxide forming salts thereof, e.g. hematite, magnetite
    • C04B2235/3274—Ferrites
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/74—Physical characteristics
    • C04B2235/76—Crystal structural characteristics, e.g. symmetry
    • C04B2235/762—Cubic symmetry, e.g. beta-SiC
    • C04B2235/763—Spinel structure AB2O4
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/80—Phases present in the sintered or melt-cast ceramic products other than the main phase

Definitions

  • the present invention relates to a dielectric compound having a composition represented by (RMbO 3- ⁇ ) n (MaO) m and having a layered triangular lattice structure, and a method for producing the same.
  • a layered triangular lattice compound typified by RFe 2 O 4 has attracted attention as a substance that exhibits dielectric properties on a principle different from that of conventional dielectrics.
  • the crystal of the compound RFe 2 O 4 has a stacked structure in which triangular lattices each composed of R, Fe, and O are stacked in layers in the c-axis direction (for example, Patent Document 1, Non-Patent Document 1, 2).
  • the above-mentioned layered triangular lattice structure of RFe 2 O 4 includes a structure in which two triangular lattice layers composed of Fe—O are stacked, and such a crystal structure depends on the geometric characteristics of the triangle. It plays the main role in the expression mechanism of physical properties characteristic of RFe 2 O 4 .
  • the multilayer structure of the triangular lattice layer of Fe-O, and the charge number of Fe in the layer of the other hand is the charge number of Fe in the other layer, while the Fe 2+ is large, on the other hand As Fe 3+ increases, they do not match.
  • the synthesis is performed at a high temperature of 1100 ° C. or more, for example.
  • the synthesis is performed under such conditions, there is a problem that the raw material powder is sintered and grain-grown during firing to produce coarse grains. With such coarse particles, when RFe 2 O 4 is used as a material for an electronic component or the like, its formability, workability, and the like are inferior.
  • energy consumption during synthesis is increased, and there is a problem in cost. Such a problem generally occurs similarly for the dielectric compound (RMbO 3 ) n (MaO) m .
  • the present invention has been made to solve the above problems, and provides a method for producing a dielectric compound capable of efficiently synthesizing a dielectric compound such as RFe 2 O 4 having a layered triangular lattice structure.
  • the purpose is to provide.
  • the dielectric compound manufacturing method has a composition of (RMbO 3- ⁇ ) n (MaO) m (R is In, Sc, Y, Dy, Ho, Er). , Tm, Yb, Lu, Ti, Ca, Sr, Ce, Sn, Hf, at least one element, Ma, Mb is Ti, Mn, Fe, Co, Cu, Ga, Zn, Al, Mg, A dielectric having a layered triangular lattice structure represented by at least one element selected from Cd with duplication allowed, n is an integer of 1 or more, m is an integer of 0 or more, and ⁇ is a real number of 0 to 0.2.
  • a method of manufacturing a body compound (1) a dielectric compound (RMbO 3- ⁇ ) n ( MaO) compounds containing R which is a raw material of m, compounds containing Ma, and a mixture of compounds containing Mb, Prepare a raw material solution containing each element of R, Ma, and Mb. And (2) a liquid phase synthesis step for obtaining a precursor solid of a dielectric compound from a raw material solution by a liquid phase method, and (3) a precursor solid obtained in the liquid phase synthesis step at a predetermined firing temperature. And a firing step of obtaining a dielectric compound powder by heating.
  • a dielectric compound (RMbO 3- ⁇ ) n ( MaO) compounds containing R which is a raw material of m, compounds containing Ma, and a mixture of compounds containing Mb
  • a liquid phase synthesis step for obtaining a precursor solid of a dielectric compound from a raw material solution by a liquid phase method, and (3) a precursor solid obtained in the liquid phase synthesis step at a predetermined
  • the reaction rate is faster than in the case of using the solid phase method, and it is possible to synthesize the compound by heating in a short time.
  • the compound can be suitably synthesized, and the resulting dielectric compound powder can be sufficiently finely divided.
  • the dielectric compound (RMbO 3- ⁇ ) n (MaO) m having a layered triangular lattice structure can be synthesized efficiently and under suitable conditions.
  • the precursor solid in the firing step, is preferably heated in a furnace at 700 ° C. or higher with an oxygen partial pressure of 10 ⁇ 12 to 1 Pa for 1 minute or longer. From the state heated to 700 ° C. or higher in the firing step, it is preferable to cool to 200 ° C. or lower within 30 minutes.
  • Ma and Mb are Fe, and the ratio of Fe 2+ to Fe 3+ in the raw material solution is preferably 0.5 to 1.5.
  • the particle size of the powder obtained by firing the precursor solid is preferably 1 to 100 nm.
  • the composition is (RMbO3 - ⁇ ) n (MaO) m (R is In, Sc, Y, Dy, Ho, Er, Tm, Yb, Lu, Ti, Ca, Sr.
  • n is an integer of 1 or more
  • m is an integer of 0 or more
  • ⁇ is a real number of 0 or more and 0.2 or less, and has a layered triangular lattice structure, a dielectric compound (RMbO 3 - ⁇ ) n (MaO) compounds containing R as a raw material for m, using a compound containing Ma, and R generated by mixing a compound containing a Mb, Ma, a raw material solution containing each element Mb, liquid
  • a dielectric compound precursor solid is generated by a phase method, The precursor solids are a powder obtained by heating to a predetermined firing temperature.
  • the particle size of the powder is preferably 1 to 100 nm.
  • the precursor solid is preferably heated to a powder in an oven at 700 ° C. or higher with an oxygen partial pressure of 10 ⁇ 12 to 1 Pa for 1 minute or more, and the powder is heated from 700 ° C. to 200 ° C. within 30 minutes. It is preferable to cool to below °C.
  • Ma and Mb are Fe and the ratio of Fe 2+ to Fe 3+ in the raw material solution is 0.5 to 1.5.
  • the dielectric compound produced by the production method of the present invention and the dielectric compound produced by this production method are obtained by synthesizing R, Ma, and R in the synthesis of the dielectric compound whose composition is represented by (RMbO 3- ⁇ ) n (MaO) m .
  • a layered triangular lattice is prepared by preparing a raw material solution containing each element of Mb, generating a precursor solid of a dielectric compound by a liquid phase method, and heating it at a predetermined firing temperature to obtain a powder of the dielectric compound.
  • a dielectric compound such as RFe 2 O 4 having a structure can be efficiently synthesized.
  • FIG. 1 is a flowchart showing an embodiment of a method for producing a dielectric compound.
  • FIG. 2 is a graph showing an X-ray diffraction pattern of a dielectric compound powder obtained using a liquid phase method and a solid phase method.
  • FIG. 3 shows SEM images of dielectric compound powders obtained using the liquid phase method and the solid phase method.
  • FIG. 4 is a graph showing an X-ray diffraction pattern of a dielectric compound powder obtained using a method in which a raw material solution is dropped into a base solution by a coprecipitation method.
  • FIG. 1 is a flowchart showing an embodiment of a method for producing a dielectric compound.
  • FIG. 2 is a graph showing an X-ray diffraction pattern of a dielectric compound powder obtained using a liquid phase method and a solid phase method.
  • FIG. 3 shows SEM images of dielectric compound powders obtained using the liquid phase method and the solid phase method.
  • FIG. 4 is a graph showing an X
  • FIG. 5 is a graph showing an X-ray diffraction pattern of a dielectric compound powder obtained using a method in which a base solution is dropped into a raw material solution by a coprecipitation method.
  • FIG. 6 is a graph showing an X-ray diffraction pattern of a dielectric compound powder obtained by cooling under different cooling conditions after firing.
  • FIG. 7 is a graph showing the magnetic characteristics of the dielectric compound powder.
  • FIG. 8 is a graph showing a Mossbauer spectrum of a dielectric compound powder.
  • FIG. 9 is a graph showing an X-ray diffraction pattern of a dielectric compound powder.
  • FIG. 10 is a graph showing an X-ray diffraction pattern of a dielectric compound powder.
  • FIG. 1 is a flowchart showing an embodiment of a method for producing a dielectric compound.
  • the compound to be synthesized is a dielectric compound RFe 2 O 4- ⁇ having a layered triangular lattice structure.
  • R represents at least one element selected from In, Sc, Y, Dy, Ho, Er, Tm, Yb, Lu, Ti, Ca, Sr, Ce, Sn, and Hf, and oxygen deficiency.
  • ⁇ is a real number between 0 and 0.2.
  • a compound containing R and a compound containing Fe are prepared as raw materials for the dielectric compound RFe 2 O 4 . And those compounds are mixed and the raw material solution containing each element of R and Fe is prepared (step S101, preparation process).
  • a raw material solution containing R and Fe and a separately prepared base solution are mixed, and a precursor (hydroxide) that is a precursor solid of RFe 2 O 4 is obtained by a kind of coprecipitation method of a liquid phase method.
  • a precipitate is generated (S102, coprecipitation step, liquid phase synthesis step).
  • the obtained precipitate of RFe 2 O 4 precursor is subjected to treatment such as washing and filtration (S103, washing step).
  • the precursor precipitate obtained by the coprecipitation method is subjected to heat treatment at a predetermined baking temperature for a predetermined baking time. Thereby, a powder of the dielectric compound RFe 2 O 4 is generated (S104, firing step).
  • the generated RFe 2 O 4 powder is subjected to an evaluation process such as characteristic measurement (S105, evaluation step).
  • S105 characteristic measurement
  • the reaction rate is faster than in the case of using the solid phase method, and it is possible to synthesize the compound by heating in a short time.
  • the compound can be suitably synthesized, and the resulting compound RFe 2 O 4 powder can be sufficiently finely divided.
  • RFe 2 O 4- ⁇ is targeted in the embodiment of FIG.
  • a manufacturing method has a crystal structure and characteristics similar to those of RFe 2 O 4 , a composition represented by (RMbO 3- ⁇ ) n (MaO) m , and a dielectric having a layered triangular lattice structure It can be suitably applied to a compound.
  • R is at least one element selected from In, Sc, Y, Dy, Ho, Er, Tm, Yb, Lu, Ti, Ca, Sr, Ce, Sn, and Hf, and Ma and Mb are Ti. , Mn, Fe, Co, Cu, Ga, Zn, Al, Mg, Cd, at least one element selected with duplication allowed, n is an integer of 1 or more, m is an integer of 0 or more, and ⁇ is 0 or more of 0 A real number of 2 or less.
  • the compound (RMbO 3- ⁇ ) n (MaO) m is to be synthesized, in the preparation step (step S101 in FIG. 1), the compound containing R, the compound containing Ma, and the Mb, which are raw materials for the compound, A compound solution, preferably a solution of these compounds is mixed to prepare a raw material solution containing each element of R, Ma, and Mb.
  • the subsequent coprecipitation step (liquid phase synthesis step), washing step, and firing step (S102 to S104) are the same as in the case of RFe 2 O 4- ⁇ .
  • the raw material solution and the base solution are mixed, and the precipitate of the precursor that is the precursor solid of the dielectric compound is obtained by the coprecipitation method.
  • the coprecipitation method which is a kind of liquid phase method, enables the dielectric compound to be synthesized in a suitable and reliable manner.
  • liquid phase method specifically, other methods besides the coprecipitation method may be used.
  • a method of obtaining a precursor solid of a dielectric compound from a raw material solution by a liquid phase method can be used.
  • uniform mixing of the raw materials at the atomic level is realized, and the synthesis at a low firing temperature is facilitated.
  • the resulting compound powder can be expected to have effects such as fine particle formation and improved characteristics.
  • the compound RFe 2 O 4 to be synthesized is LuFe 2 O 4 .
  • a first solution composed of a solution of a compound containing Lu is prepared.
  • Lu 2 O 3 weighed to 0.5 g (1.25 mmol) is dissolved in 4 ml of hot concentrated nitric acid (HNO 3 , 60 wt%) to form a Lu 3+ solution.
  • 4 ml of concentrated nitric acid is added again at room temperature to completely dissolve it.
  • the 2nd solution consisting of the solution of the compound containing Fe is produced.
  • the Fe 2+ solution is most simply prepared by adding 10 ml of distilled water to FeC 2 O 4 .2H 2 O weighed to 0.9 g (5 mmol). At this stage, iron oxalate is not completely dissolved.
  • a solution containing Fe 2+ and Fe 3+ can be obtained in a solution of a compound containing Fe.
  • the ratio of Fe 2+ to Fe 3+ in the solution can be adjusted to 0.5 to 1.5 by adjusting the blending ratio of iron oxalate and iron sulfate.
  • a mixed solution of the first solution and the second solution to be a raw material solution is prepared.
  • This mixed solution is prepared by adding the second solution to the first solution obtained in the above step.
  • the contents of the beaker are washed out with a small amount of distilled water so that iron oxalate or iron sulfate remaining at the bottom of the beaker is completely moved to the first solution side.
  • This mixed solution becomes a raw material solution for the LuFe 2 O 4 synthesis.
  • LuFe 2 O 4 precursor (hydroxide) powder is synthesized by coprecipitation reaction (S102, S103).
  • the mixed raw material solution obtained in the above step is dropped dropwise with a dropper into 10 ml of NH 3 water (28 wt%) as a base solution with stirring. And a base solution are mixed.
  • aqueous NaOH in place of NH 3 water.
  • a precursor solid of the dielectric compound LuFe 2 O 4 is generated as a precipitate at the bottom of the beaker.
  • the generated precipitate is filtered through a membrane filter (0.2 ⁇ m), and the precipitate is rinsed once with distilled water.
  • the obtained precipitate is dried in a dryer at 100 ° C. for 24 hours.
  • the dried precursor solid is in the form of a powder having a particle size of 1 to 100 nm, and if this precursor solid is baked as it is, a dielectric compound having a particle size of 1 to 100 nm can be obtained. it can.
  • the LuFe 2 O 4 phase is synthesized by firing (S104).
  • firing as a pellet for measuring physical property values
  • dry powder of the precursor precipitate produced in the above process is put into a ⁇ 12 mm mold and press-molded into a pellet.
  • the obtained pellet-shaped sample is vacuum fired. Specifically, a sample is put into a quartz tube sealed on one side, and a vacuum is drawn from the other side with a rotary pump. This quartz tube is put into an electric furnace and heated from a room temperature to a predetermined firing temperature (for example, 900 ° C.) at a predetermined temperature increase rate (for example, 10 ° C./min). At this time, the inside of the quartz tube is continuously evacuated by a rotary pump.
  • a predetermined firing temperature for example, 900 ° C.
  • a predetermined temperature increase rate for example, 10 ° C./min
  • the electric furnace When the electric furnace reaches a predetermined temperature, the electric furnace is held at that temperature for a predetermined baking time (for example, 1 hour). Similarly, during this time, the inside of the quartz tube is continuously evacuated by the rotary pump.
  • a predetermined baking time for example, 1 hour.
  • the quartz tube When the firing time has elapsed, the quartz tube is quickly taken out of the electric furnace, immediately put into water and rapidly cooled. At this time, the inside of the quartz tube is continuously evacuated by the rotary pump. Thus, a powder of the dielectric compound LuFe 2 O 4 is obtained.
  • a method of strictly controlling the O 2 partial pressure of the reaction field by flowing a CO / CO 2 mixed gas into the quartz tube may be used for a portion that is evacuated by a rotary pump.
  • the powder of a compound LuFe 2 O 4 obtained by the above method may be carried out Characterization if necessary (S105).
  • Characterization if necessary S105
  • SEM scanning electron microscope
  • the RFe 2 O 4 powder synthesis method using the liquid phase method such as the coprecipitation method can suitably synthesize the compound at a low temperature in a shorter time than the solid phase method.
  • the compound powder can be sufficiently finely divided.
  • FIG. 2 is a graph showing an X-ray diffraction pattern of a dielectric compound powder obtained by using a liquid phase method and a solid phase method.
  • FIG. 2 (a) shows a case where baking is performed at 900 ° C. for 1 hour.
  • FIG. 2B shows the X-ray diffraction result of the compound powder obtained by firing for 1 hour at a firing temperature of 1200 ° C.
  • Rigaku RINT2000 is used as an X-ray diffractometer, and measurement is performed by a powder X-ray diffraction method using Cu—K ⁇ rays (output: 40 kV, 200 mA).
  • graphs A1 and A3 show the results of compound synthesis by the liquid phase method
  • graphs A2 and A4 show the results of synthesis by the conventional solid phase method.
  • the liquid phase method obtained the LuFe 2 O 4 phase in a substantially single phase in a short time firing as compared with the solid phase method.
  • the crystallite size of the LuFe 2 O 4 powder was determined from these X-ray diffraction results. Under the firing conditions of 900 ° C. for 1 hour, the liquid phase method was 49.7 nm, the solid phase method was 63.3 nm, and 1200 Under baking conditions of 1 ° C. for 1 hour, the liquid phase method was 73.5 nm and the solid phase method was 72.9 nm.
  • FIG. 3 is a view showing an SEM image of a dielectric compound powder obtained by using the liquid phase method and the solid phase method
  • FIG. FIG. 3 (b) shows an SEM photograph of the compound powder obtained by firing the synthesized powder by the solid phase method at a firing temperature of 900 ° C. for 1 hour. Is shown.
  • FIG. 4 is a graph showing an example of an X-ray diffraction pattern of a dielectric compound powder obtained using a coprecipitation method.
  • a method for generating a precipitate of the precursor of the compound LuFe 2 O 4 by a coprecipitation method a method of generating a precipitate by dropping a mixed solution that is a raw material solution into NH 3 water that is a base solution, The X-ray-diffraction result of the compound powder synthesize
  • graphs B1, B2, and B3 show the synthesis results when the firing temperatures are 900 ° C., 800 ° C., and 700 ° C., respectively.
  • a LuFe 2 O 4 phase is generated to some extent even at a firing temperature of 700 ° C., and further, at a firing temperature of 800 ° C. and 900 ° C., LuFe 2 it can be seen that the O 4 phase are mass produced.
  • FIG. 5 is a graph showing another example of an X-ray diffraction pattern of a dielectric compound powder obtained by using a coprecipitation method.
  • a method of generating a precipitate of the precursor of the compound LuFe 2 O 4 by the coprecipitation method unlike the above method, a method of generating a precipitate by dropping NH 3 water into the mixed solution is used.
  • combined by heating the obtained deposit at the predetermined baking temperature for 1 hour in a vacuum is shown.
  • graphs C1, C2, and C3 show the synthesis results when the firing temperatures are 900 ° C., 800 ° C., and 700 ° C., respectively.
  • the firing temperatures are 900 ° C., 800 ° C., and 700 ° C., respectively.
  • the LuFe 2 O 4 phase is generated, but the method of dropping the raw material solution into the base solution is used.
  • the firing temperature is 900 ° C.
  • a large amount of different phases such as Lu 2 O 3 and FeO are mixed, and it is difficult to make LuFe 2 O 4 into a single phase under the firing conditions for 1 hour. .
  • the specific synthesis conditions and synthesis method are dropped while stirring the raw material solution in the base solution in the coprecipitation step. It is preferable to mix the raw material solution and the base solution.
  • a base solution is dropped onto the raw material solution side, and the pH is raised to a predetermined value to obtain a precursor (hydroxide) precipitate (see FIG. 5).
  • a precursor hydrooxide precipitate
  • the solubility of ions generally varies depending on the ion species, for example, in the synthesis of RFe 2 O 4 , the composition of R 3+ , Fe 2+ , and Fe 3+ changes between the initial and final stages of precipitation by coprecipitation reaction There is a possibility that.
  • NH 3 solution an ammonia solution
  • various base solutions such as a NaOH solution can be used.
  • NaOH solution Na may enter impurities in the resulting dielectric compound powder, which may affect the physical properties thereof. Therefore, the NH 3 solution is more preferable in this respect.
  • Lu 2 O 3 As for the specific starting material compounds used in the raw material solution, in the above example, for compounds LuFe 2 O 4 to be combined, Lu 2 O 3, nitric acid, are used FeC 2 O 4 ⁇ 2H 2 O
  • various raw materials may be used.
  • the above-described Lu 2 O 3 is available at a low price, but other compounds may be used as raw materials.
  • iron-containing compounds other iron compounds such as iron chloride and iron sulfate may be used.
  • iron oxalate is used in consideration of the influence of the residual elements after synthesis.
  • the firing conditions of the precursor obtained by a liquid phase method such as a coprecipitation method it is preferable to heat the precursor solid at a firing temperature of 900 ° C. or less in the firing step. In this case, the synthesis of the dielectric compound can be performed at a sufficiently low temperature.
  • the precursor solid is heated for a firing time of 2 hours or less in the firing step.
  • the synthesis of the dielectric compound can be performed in a sufficiently short time.
  • the precursor solid when firing in an atmosphere in which the oxygen partial pressure is adjusted to 10 ⁇ 12 to 1 Pa, the precursor solid can be sintered only by maintaining the state of 700 ° C. or higher for 1 minute or longer.
  • the processing time can be greatly reduced and the manufacturing cost can be greatly reduced.
  • the precursor solid can be effectively fired by using a rotary kiln furnace.
  • a rotary kiln furnace when used, a dielectric compound can be obtained directly from a precursor solid in a powder state, and the manufacturing cost can be easily reduced.
  • the sintered dielectric compound it is preferable to suppress the appearance of grain growth and different crystalline states by rapidly cooling the sintered dielectric compound. From the state heated to 700 ° C. or higher to 200 ° C. or lower within 30 minutes. It is preferable to cool.
  • the dielectric compound heated to 700 ° C. or higher and sintered can be simply taken out of the heating furnace, and the dielectric compound can be discharged out of the heating furnace with an appropriate discharging means to be naturally cooled. You can just let it.
  • FIG. 6 is a graph showing an X-ray diffraction pattern of a powder of the dielectric compound LuFe 2 O 4 when the dielectric compound heated to 800 ° C. and sintered is cooled under different cooling conditions.
  • F1 in FIG. 6 is a graph when the precursor solid is heated at 800 ° C. for 1 hour and calcined and then rapidly cooled by taking it out of the heating furnace.
  • F2 in FIG. After heating for 1 hour and baking, the heating condition of the heating furnace is controlled and the temperature is cooled to 200 ° C. or less over about 3 hours.
  • the LuFe 2 O 4 phase can be effectively generated by rapid cooling.
  • FIG. 7 is a graph showing the magnetic properties (magnetization-temperature curve) of the LuFe 2 O 4 powder synthesized by the above method using the coprecipitation method.
  • FIG. 8 is a graph showing the room temperature Mossbauer spectrum of the LuFe 2 O 4 powder. Here is shown the measurement results of the NH 3 compound powder mixed solution precipitate obtained was added dropwise to have been fired to synthesize at 900 ° C. in water is a base solution.
  • the LuFe 2 O 4 crystal powder obtained by the above method has the same characteristics as the LuFe 2 O 4 crystal synthesized using the solid phase method (Non-patent Document). 6). That is, it is considered that the RFe 2 O 4 crystal synthesized using the coprecipitation method exhibits the same interesting physical properties as those of the RFe 2 O 4 crystal synthesized using the solid phase method so far. .
  • FIG. 9 is a graph showing an X-ray diffraction pattern of a powder of dielectric compound LuFe 2 O 4 obtained by the above synthesis method. Here is shown the measurement results of the NH 3 compound powder mixed solution precipitate obtained was added dropwise to have been fired to synthesize at 900 ° C. in water is a base solution.
  • graphs D1, D2, D3, and D4 show the synthesis results when the firing time is 2 hours, 1 hour, 0.5 hours, and 0 hours, respectively.
  • the firing time of 0 hour means that the quartz tube containing the sample is heated from room temperature to a firing temperature of 900 ° C. at a predetermined rate of temperature rise, and when the temperature reaches 900 ° C., the sample is not held at the firing temperature. The case where the heat treatment is immediately finished is shown.
  • the LuFe 2 O 4 phase is considerably generated. From this, it can be seen that according to the synthesis method described above, the compound powder can be synthesized even in a very short time. However, in the synthesis example shown in FIG. 9, the Lu 2 O 3 phase exists to some extent when firing is performed for a short time. On the other hand, when firing for a relatively long time at 1 hour or longer, the Lu 2 Fe 3 O 7 phase appears.
  • the concentration of the raw material solution in the coprecipitation method specifically, the concentration of the mixed solution dropped into the NH 3 water that is the base solution will be described.
  • FIG. 10 is a graph showing an X-ray diffraction pattern of a powder of dielectric compound LuFe 2 O 4 obtained by the above synthesis method.
  • Lu 3+ to NH 3 in water the precipitate obtained was added dropwise to Fe 2+ solution 900 ° C., shows the measurement results for compound powder fired to synthesized in 1 hour.
  • graphs E1, E2, and E3 show the synthesis results when the concentration of the LuFe 2 aqueous solution is 0.05 mol / l, 0.1 mol / l, and 0.2 mol / l, respectively.
  • the LuFe 2 O 4 phase is generated in the entire concentration range.
  • the LuFe 2 aqueous solution concentration is 0.1 mol / l, which is closest to the single phase of the LuFe 2 O 4 phase, and in other cases, the LuFeO 3 phase, which is a different phase, is present. It is mixed.
  • the method for producing a dielectric compound according to the present invention is not limited to the above-described embodiment and configuration examples, and various modifications are possible.
  • the conditions for generating the precursor solid of the dielectric compound by the coprecipitation method and the firing conditions of the precursor solid are not limited to the above-described conditions, and various conditions may be changed as necessary.
  • various methods other than the coprecipitation method may be used as the liquid phase method used for producing the precursor solid of the dielectric compound.
  • a liquid phase method include a sol-gel method using a metal alkoxide as a raw material and a complex polymerization method using an organometallic complex as a raw material.
  • the present invention can be used as a method for producing a dielectric compound capable of suitably synthesizing a dielectric compound such as RFe 2 O 4 .

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Abstract

L'invention porte sur un composé diélectrique et sur un procédé de fabrication dudit composé avec lequel des composés diélectriques tels que RFe2O4 peuvent être efficacement synthétisés. Dans la fabrication d'un composé diélectrique qui est représenté par (RMbO3-δ)n(MaO)m et qui a une structure maillée, triangulaire et stratifiée, un composé contenant R comme matière de départ du composé diélectrique, un composé contenant Ma et un composé contenant Mb sont mélangés pour préparer une solution de matière de départ contenant chacun des éléments, à savoir R, Ma et Mb (S101, étape de préparation), et un précurseur solide du composé diélectrique est créé à partir de la solution de matière de départ à l'aide d'un procédé en phase liquide, telle qu'une co-précipitation (S102, une étape de synthèse en phase liquide). Ensuite, le précurseur solide obtenu est chauffé à une température de calcination prescrite de façon à obtenir une poudre de composé diélectrique (S104, étape de calcination).
PCT/JP2009/070323 2008-12-03 2009-12-03 Composé diélectrique et son procédé de fabrication WO2010064686A1 (fr)

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Publication number Priority date Publication date Assignee Title
JPS52101499A (en) * 1976-02-21 1977-08-25 Kagaku Gijutsucho Mukizai Singleecrystal magnetic semiconductor of yttrium diferrous tetraoxigen compoun *yfe204* and method of manufacture thereof
JP2002352626A (ja) * 2001-05-25 2002-12-06 Central Res Inst Of Electric Power Ind 誘電体材料とその製造方法及び当該誘電体材料を利用したコンデンサー並びに電力貯蔵システム
JP2007223886A (ja) * 2005-11-22 2007-09-06 Japan Synchrotron Radiation Research Inst 物質中の電子密度を双極子状に分布させることで誘電体特性を実現する方法および材料

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52101499A (en) * 1976-02-21 1977-08-25 Kagaku Gijutsucho Mukizai Singleecrystal magnetic semiconductor of yttrium diferrous tetraoxigen compoun *yfe204* and method of manufacture thereof
JP2002352626A (ja) * 2001-05-25 2002-12-06 Central Res Inst Of Electric Power Ind 誘電体材料とその製造方法及び当該誘電体材料を利用したコンデンサー並びに電力貯蔵システム
JP2007223886A (ja) * 2005-11-22 2007-09-06 Japan Synchrotron Radiation Research Inst 物質中の電子密度を双極子状に分布させることで誘電体特性を実現する方法および材料

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
KATANO S. ET AL.: "Crystal and magnetic structure of stoichiometric YFe204", PHYSICA B, vol. 213-214, 1995, pages 218 - 220 *

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