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WO1998039269A1 - Procede de production d'une ceramique perovkite de structure definie - Google Patents

Procede de production d'une ceramique perovkite de structure definie Download PDF

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Publication number
WO1998039269A1
WO1998039269A1 PCT/EP1998/001308 EP9801308W WO9839269A1 WO 1998039269 A1 WO1998039269 A1 WO 1998039269A1 EP 9801308 W EP9801308 W EP 9801308W WO 9839269 A1 WO9839269 A1 WO 9839269A1
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Prior art keywords
ceramic
particles
density
temperature
ceramic powder
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PCT/EP1998/001308
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German (de)
English (en)
Inventor
Tobias Erny
Frank Hutter
Karl Lubitz
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Siemens Aktiengesellschaft
Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
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Publication of WO1998039269A1 publication Critical patent/WO1998039269A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
    • C01B13/14—Methods for preparing oxides or hydroxides in general
    • C01B13/32—Methods for preparing oxides or hydroxides in general by oxidation or hydrolysis of elements or compounds in the liquid or solid state or in non-aqueous solution, e.g. sol-gel process
    • C01B13/328—Methods for preparing oxides or hydroxides in general by oxidation or hydrolysis of elements or compounds in the liquid or solid state or in non-aqueous solution, e.g. sol-gel process by processes making use of emulsions, e.g. the kerosine process
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G33/00—Compounds of niobium
    • C01G33/006—Compounds containing niobium, with or without oxygen or hydrogen, and containing two or more other elements
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • 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
    • C04B35/48—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 zirconium or hafnium oxides, zirconates, zircon or hafnates
    • C04B35/49—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 zirconium or hafnium oxides, zirconates, zircon or hafnates containing also titanium oxides or titanates
    • C04B35/491—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 zirconium or hafnium oxides, zirconates, zircon or hafnates containing also titanium oxides or titanates based on lead zirconates and lead titanates, e.g. PZT
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/30—Three-dimensional structures
    • C01P2002/34—Three-dimensional structures perovskite-type (ABO3)
    • 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
    • C01P2004/60—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
    • C01P2006/14—Pore volume
    • 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
    • C01P2006/40—Electric properties

Definitions

  • Perovskite ceramics have been used for many years and to a considerable extent for electro-ceramic components. Representing a variety of material systems and applications, only barium titanate (for cold conductors and condensers), lead magnesium niobate (for capacitors) and lead titanate zirconate (for piezoelectric transducers) are mentioned here.
  • electro-ceramic components are essentially determined by the stoichiometry, the density, the grain size and the micro-homogeneity of the sintered ceramic. Because of the high degree of dependence on these parameters, it is necessary to select processes and material compositions that can be used to precisely and reproducibly set known parameters.
  • Known manufacturing processes generally have the major disadvantage that final density (after sintering), grain size, material composition and micro-homogeneity cannot be set freely and independently of one another. Rather, several of these parameters are usually mutually dependent in these methods.
  • a low final density can be coupled, for example, with a small / large grain size or with a strong microinhogenicity in the ceramic.
  • the grain size and final density after sintering are in turn heavily dependent on the composition of the ceramic. For example, it is often necessary to add high dopants to the ceramic, which are actually undesirable for their electrical properties in order to achieve a compromise of a high final density in conjunction with a necessary grain size.
  • a known standard process for the production of perovskite ceramics is the mixed-oxide process. Individual Loxides of the components are crushed and mixed in a first grinding. During the subsequent calcination, the perovskite powder is formed, which is crushed again in a second grinding. These primary powder particles, which are then used in molding processes to produce ceramics of the desired external shape, are small compared to the later grain size in the ceramic.
  • the shaping takes place, for example, by dry pressing, slip casting or film drawing.
  • material composition, compaction and grain growth are inextricably linked.
  • a non-optimal micro-homogeneity is achieved in the sintered ceramic.
  • typical final densities of 94 to 96 percent of the theoretical density are obtained, with optimized foil technology 98 percent.
  • discrete mixed ceramics are not at all, only extremely difficult to produce gradient materials, since the processes show strong interdiffusion and different shrinkage behavior, which is linked to the chemical composition and can therefore differ in the gradient material.
  • An undoped lead zirconate titanate piezoceramic for example, cannot be produced in sufficient density in the mixed-oxide method, since in the course of sintering, early onset strong grain growth prevents a later high compression.
  • the micro-homogeneity in a uniform ceramic component has hitherto only been able to be increased by using special chemically prepared starting powders for the mixed-oxide process or by using chemically prepared perovskite powders for shaping.
  • high final densities close to 100 percent of the theoretical density in perovskite ceramics have so far only been achieved by sintering in pure oxygen.
  • a decoupling of compaction and grain growth has so far been possible only with a very complex process.
  • the gases contained in the pores of the ceramic only oxygen can escape through the perovskite ceramic structure and thus diffuse completely out of the ceramic.Therefore, the perovskite ceramic has so far been hot-pressed in pure oxygen at low temperature in order to obtain a completely dense ceramic with a fine grain size.
  • the grain size can be increased within certain limits by re-sintering at a higher temperature and extended holding time.
  • the object of the present invention is to specify a method for producing a perovskite ceramic with a defined structure, which is independent of a selected ceramic composition and in which any desired structure can be reproducibly produced in a simple manner.
  • the invention is based on an emulsion process known in principle. This enables the simultaneous precipitation of more than two and up to eight cations from one emulsion.
  • the particles have a high micro-homogeneity and have a spherical to almost ideal spherical shape.
  • the precipitated raw particles which are isolated by drying are calcined, the outer shape of which is retained, no agglomeration occurs and a free-flowing perovskite ceramic powder is obtained.
  • This calcination step while maintaining the spherical outer shape of the particles is used according to the invention to regulate the ceramic structure.
  • This calcination step while maintaining the spherical outer shape of the particles is used according to the invention to regulate the ceramic structure.
  • the temperature used for calcining takes place within the ceramic particles are precompressed, which changes the microstructure of the particles and their extent changes later
  • the ceramic powder is then mixed with binder and optionally solvent, subjected to a shaping process as a paste or slip into a green body and finally sintered to form a solid ceramic.
  • a low calcination temperature in the lower range of a temperature interval ranging from 600 to 900 ° C. a nanocrystalline structure in the particles remains largely as it is obtained from the emulsion as a result of the precipitation process. Only a slight shrinking process of the particles is observed. The latter therefore still have a high porosity after calcination. If one sinters such porous ceramic powder, the sintering process starts at relatively low temperatures and initially leads to a first one from which
  • the microstructure that is to say the grain size of the crystallites within the particles, can be adjusted via the duration and temperature of the calcination, a longer grain size resulting in a larger grain size and a smaller grain size with a shorter calcination time.
  • microstructure parameters results from the regulation of the emulsification conditions.
  • the higher the shear forces selected when producing the emulsion the smaller the droplet size of the disperse phase, which in turn is proportional to the size of the precipitated ceramic raw particles.
  • Average particle sizes between 1 and 30 ⁇ m can thus be produced in a targeted manner using the emulsification conditions. Since the particle size in turn represents the upper limit for the grain size of the crystallites, the crystallite size in the ceramic can also be adjusted in this way.
  • the ceramic powder used also facilitates sintering into shaped bodies, so that the invention enables improved production of large-volume ceramic components.
  • a simple sintering in air results in defect-free components with a final density close to 100 percent.
  • the ceramic powders obtained as an intermediate in the process according to the invention consist of particles with an almost ideal spherical shape and a recrystallized, mechanically undamaged surface.
  • the ceramic powder according to the invention is very coarse. Nevertheless, it makes shaping easier thanks to its strongly reduced tendency to agglomerate.
  • the spherical shape also makes it possible to achieve a high bulk density and thus a high degree of filling of up to 74 volume percent even with a powder with a uniform spherical diameter, which is obtained, for example, by sieving. If the particle size distribution is further optimized to a high bulk density by mixing several different fractions, each with a uniform spherical diameter, then bulk densities of up to 90 volume percent can be generated with bi- or trimodal spherical diameter distributions.
  • the relatively coarse ceramic powders are well suited for all shaping processes and in particular for pasteuse processes such as extrusion, injection molding and above all for slip processes such as slip casting, sedimentation and film drawing.
  • the uniform and almost ideal surface of the ceramic particles enables a reduction in the proportion of binder, easier liquefaction in the slip process and much easier debinding through the defined diffusion and degassing paths between the ceramic particles that are retained for a long time even during sintering. These advantageous properties are particularly important in the production of large-volume ceramic components and improve and facilitate their production.
  • FIG. 1 shows the SEM image of powder particles of the ceramic powder used according to the invention.
  • Figure 2 shows a schematic cross section of a porous ceramic.
  • Figure 3 shows a schematic cross section of a high-density ceramic.
  • a powder made of neodymium-doped lead zirconate titanate (PZT) is to be produced for a pyro- or piezoelectric ceramic based on PZT.
  • Organometallic compounds of the metals zirconium and titanium serve as starting materials for the PZT synthesis.
  • the liquid alcoholates have proven themselves for zirconium and titanium, for example that
  • a stable solution of the cations required for PZT is achieved by complexing with a suitable complexing agent, for example a 1,3-diketone and in particular with acetylacetone.
  • alcoholic solutions of zirconium and titanium alcoholates are mixed with acetylacetone, and then solid lead acetate is dissolved in them.
  • the complexed bonds isolated as solids which can then be dissolved in water again.
  • aqueous solution of the complexed compounds is produced, it being possible to add to this phase the dopants to be added in only a small proportion, for example neodymium, as an acetate and also to dissolve them.
  • the lead, zirconium, titanium and neodymium contents are determined analytically and, if necessary, corrected by adding correction solutions containing the missing cations until they match the desired target stoichiometry within the analytical accuracy.
  • the aqueous solution with the stoichiometric content of the PZT components is now weighed.
  • an emulsifying device an equal proportion of petroleum ether (PE60 / 95) is mixed with an emulsifier, which favors a water-in-oil emulsion.
  • the aqueous solution is slowly added to the petroleum ether and emulsified. During the addition, the temperature is allowed to rise to approximately 40 ° C., which promotes the formation of a water-in-oil emulsion.
  • the solution can remain in the emulsifying apparatus under emulsifying conditions and be further mixed.
  • gaseous ammonia is introduced into the emulsion for precipitation until the pH value changes to the basic range. A suspension of solid particles in the solvent is obtained.
  • the organic and aqueous phase or water and organic solvent are then removed and the solid ceramic powder is isolated in this way.
  • a spray dryer operating in a circuit can be used for this purpose.
  • Advantageous inlet temperatures are between 230 and 250 ° C, while the outlet temperature is preferably set to 100 to 130 ° C.
  • the temperature of the spray cylinder and thus the maximum temperature to which the powder is heated in the spray dryer is closer to the outlet temperature and, for example, 140 to 170 ° C.
  • the material throughput can be regulated by the atomizing pressure in the atomizing nozzle of the spray dryer and / or by means of the pump with which the suspension is fed into the atomizing nozzle.
  • ceramic raw particles are obtained which still contain a relatively high proportion of organic constituents of approx. 35 percent.
  • the raw particles are calcined in an oven and in an atmosphere which at least contains oxygen or consists entirely of oxygen.
  • the raw particles can be placed in a muffle furnace at a low bed height of, for example, 2 cm in flat dishes.
  • the calcination is carried out by slowly heating the furnace to the desired calcination temperature, which is selected in the range from 600 to 900 ° C and set depending on the desired ceramic structure. Then it is slowly cooled again.
  • FIG. 1 shows an SEM photograph of the ceramic powder obtained.
  • the almost ideal spherical shape of the ceramic particles and their mechanically undamaged surface are clearly visible.
  • the particles remain isolated during the calcination and do not form agglomerates by sticking together.
  • the ceramic powder is therefore free-flowing and can be separated into different fractions in a simple manner, for example by sieving according to the particle size.
  • the size of the ceramic particles is regulated by setting the emulsification conditions. Act higher on the emulsion kerker shear forces, for example a higher mixing speed, finer inlet nozzles or a higher inlet pressure result in a smaller droplet size and thus a smaller particle size of the dried ceramic particles.
  • the average particle diameter of the ceramic powder can thus be set to sizes between 1 and 30 ⁇ m.
  • the grain sizes or the microstructure of the ceramic particles can be influenced by suitable choice of temperature and duration of the calcination.
  • the originally nanocrystalline microstructure within the raw ceramic particles can be coarsened at a sufficiently high calcination temperature, the grains being able to assume at most the size of the particles given by the emulsion conditions. Even with a low calcination temperature, the grain size can be increased to the maximum value corresponding to the particle size by correspondingly longer calcination.
  • the calcination is carried out in a rotary kiln in which the tendency to form agglomerates is further suppressed and is even less dependent on compliance with exact calcining conditions.
  • a measurement of the piezoelectric characteristic data of a PZT ceramic can be used to easily determine the exact stoichiometry and / or the desired micro-homogeneity .
  • dense test specimens are produced from the ceramic powder, provided with electrodes and measured. This is achieved by pressing a ceramic powder and subsequent sintering. Sintering takes place in air at temperatures between 100 and 1250 ° C.
  • the Curie temperature of the Piezokera ik depends sensitively on the stoichiometry and in particular on the zirconium / titanium ratio and the neodymium content.
  • the measurement of the Curie temperature on different test specimens shows only slight deviations between different batches of ceramic powder produced. This proves the good reproducibility of the process in relation to the desired stoichiometry.
  • a relative permeability ⁇ r of up to 1730 is achieved.
  • the measured coupling factors kp are greater than 0.65, while the piezoelectric charge constant d3 has a very high value of over 700 pC / N.
  • a PZT ceramic powder is produced as described, the maximum calcination temperature being set in the lower range of the specified interval from 600 to 900 °.
  • the primary crystallites within the ceramic particles are then still small, and the ceramic particles still contain considerable porosity in their interior.
  • the ceramic powders mixed with binder are subsequently converted into green shaped bodies (green bodies) and then sintered to form solid ceramics.
  • the sintering can be carried out in air or in a pure oxygen atmosphere, with final densities of almost 100 percent being achieved in both cases.
  • the formation of a high-density ceramic is supported if the ceramic powders have a particle size distribution that is optimized with regard to high bulk density.
  • High fill levels of up to 90 percent in the green body are achieved with bi- or trimodal particle size distributions, for example with a trimodal mixture which has corresponding amounts with average particle diameters of 3 ⁇ m, 8 ⁇ m and 25 ⁇ m.
  • Compression phase When sintering, an early one starts Compression phase at a relatively low temperature. In this phase, the particles become denser, which leads to grain growth. In a further compression phase at a higher temperature, the interspaces between the particles close, with pore channels remaining until the end, which allow the gas obtained, in particular also the nitrogen (when sintered in air) to escape completely, and complete compression in the ceramic during the Allow sintering in the very last phase.
  • Such a high-density ceramic is shown in detail in a schematic cross section in FIG. It has no pores and a homogeneous microstructure with grain sizes that are approximately the same across the entire solid ceramic body.
  • a PZT powder is produced as specified, the maximum calcination temperature in the upper range of the specified interval being chosen from 600 to 900 ° C. This results in an already sufficient compression inside the ceramic particles, whereby a grain size sufficient for the piezo or pyroelectric properties of the later porous ceramic is obtained by recrystallization within the particles.
  • a ceramic powder fraction with the largest possible particle diameter of, for example, 25 ⁇ m is selected for producing the green shaped bodies. Together with a relatively high binding proportion, this enables the production of green bodies with an initial density of less than 50 percent by volume of ceramic material before sintering. Due to a greatly reduced sintering temperature, the sintering process is only carried out to such an extent that the ceramic particles are just firmly bonded to one another. This means that the layering of the spherical ceramic powder particles given porosity largely preserved. The result is a solid ceramic with high porosity, which nevertheless has a sufficient grain size and, due to the homogeneous powder particles, an excellent micro-homogeneity. Despite the reduced sintering temperature, such a body shows the ideal values of a porous material in terms of its structure and its piezoelectric properties, in which both the pore spaces and the ceramic are interconnected in all three dimensions.
  • FIG. 2 shows a section of a porous ceramic produced in this way in a schematic cross section.
  • the gap 2 remaining between the solid ceramic particles 1 is responsible for the high to 50 percent porosity of the ceramic body produced.
  • Such porous components made of lead titanate zirconate can be used, for example, as air-ultrasonic transducers.
  • ceramic gradient materials and components with specific mixing inhomogeneities can also be produced in a simple manner.
  • a green body is produced from differently composed ceramic powders, for example by means of a layer structure with a continuously varying raw ceramic mass.
  • a ceramic with targeted micro-ingenuity can be produced with a ceramic powder, which is obtained by mixing several ceramic powders with different compositions.
  • the ceramic powders are preferably calcined as pure fractions at high temperature in order to achieve high grain growth or a sufficient grain size of the powder already in the powder phase. Powders of different compositions are then mixed and, if necessary, the mixing ratio is changed continuously in the shaped body in accordance with a desired gradient.
  • the different material compositions in the individual ceramic particles can be retained for a long time. Interdiffusion only takes place in the final phase of sintering when the gaps between the ceramic particles are compacted, and only to a small extent. In this way, the desired micro-inhomogeneities with regard to the ceramic composition are largely retained and, for example, a ceramic with a flatter temperature response is obtained.
  • shrinkage behavior during sintering is decisively influenced by the size and size distribution of the ceramic particles in the green body
  • shrinkage behavior independent of the composition can be achieved in particular with gradient materials by appropriate selection of sizes and size distribution of the ceramic particles.
  • a ceramic solid with a homogeneous microstructure and sufficient strength can still be produced.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Composite Materials (AREA)
  • Compositions Of Oxide Ceramics (AREA)

Abstract

L'invention concerne un procédé permettant d'obtenir des poudres de céramique pérovkite à plusieurs composants, présentant des particules homogènes de forme et approximativement sphérique, par précipitation commune à partir d'une émulsion. On obtient à partir de ces poudres céramiques des corps moulés solides en céramique par régulation ciblée des conditions de calcination. La porosité de ces corps peut être ajustée librement dans une plage de 0 à 50 pourcents quelle que soit la composition.
PCT/EP1998/001308 1997-03-06 1998-03-06 Procede de production d'une ceramique perovkite de structure definie WO1998039269A1 (fr)

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DE19709216 1997-03-06
DE19709216.0 1997-03-06

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WO1998039269A1 true WO1998039269A1 (fr) 1998-09-11

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2164623A4 (fr) * 2007-06-11 2012-10-24 Univ City New York Res Found Préparation de nanocristaux perovskite à partir de micelles inverses

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0206575A2 (fr) * 1985-06-17 1986-12-30 Mra Laboratories, Inc. Procédé de préparation de poudres fines
WO1992021611A1 (fr) * 1991-06-03 1992-12-10 Institut für Neue Materialien Gemeinnützige GmbH Procede pour la production de particules d'oxyde a l'echelle nanometrique
JPH05306121A (ja) * 1992-04-30 1993-11-19 Murata Mfg Co Ltd チタン酸バリウム系磁器原料粉末の製造方法
US5484766A (en) * 1994-02-14 1996-01-16 Electric Power Research Institute, Inc. Preparation of Bi-Pb-Sr-Ca-Cu-O (2223) superconductors

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0206575A2 (fr) * 1985-06-17 1986-12-30 Mra Laboratories, Inc. Procédé de préparation de poudres fines
WO1992021611A1 (fr) * 1991-06-03 1992-12-10 Institut für Neue Materialien Gemeinnützige GmbH Procede pour la production de particules d'oxyde a l'echelle nanometrique
JPH05306121A (ja) * 1992-04-30 1993-11-19 Murata Mfg Co Ltd チタン酸バリウム系磁器原料粉末の製造方法
US5484766A (en) * 1994-02-14 1996-01-16 Electric Power Research Institute, Inc. Preparation of Bi-Pb-Sr-Ca-Cu-O (2223) superconductors

Non-Patent Citations (3)

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Title
DATABASE WPI Section Ch Week 9351, Derwent World Patents Index; Class L03, AN 93-408753, XP002070196 *
NARITA T: "JOURNAL OF THE CERAMIC SOCIETY OF JAPAN, INTERNATIONAL EDITION", JOURNAL OF THE CERAMIC SOCIETY OF JAPAN, INTERNATIONAL EDITION, vol. 104, no. 7, July 1996 (1996-07-01), pages 622 - 626, XP000638393 *
PUSHAN AYYUB ET AL: "SECONDARY RECRYSTALLIZATION DURING SINTERING OF YBA2CU3O7 DERIVED FROM WATER-IN-OIL MICROEMULSION", MATERIALS LETTERS, vol. 10, no. 9 / 10, 1 February 1991 (1991-02-01), pages 431 - 436, XP000177367 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2164623A4 (fr) * 2007-06-11 2012-10-24 Univ City New York Res Found Préparation de nanocristaux perovskite à partir de micelles inverses

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