Chemistry of inorganic compounds – Rare earth compound
Patent
1995-05-15
1997-11-18
Langel, Wayne
Chemistry of inorganic compounds
Rare earth compound
423593, 423594, 423595, 423596, 423598, 423599, 423600, C01F 1700, C01G 2304, C01G 5104, C01G 5304
Patent
active
056884800
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a complex metal oxide powder comprising at least two metal elements which is used as a raw material powder of an oxide ceramic that is used as a functional material or a structural material, which is used in a dispersed state as a filler or a pigment, or which is used as a raw material powder for the production of a single crystal or for flame spray coating, and a method for the production thereof.
PRIOR ART
In general, an oxide ceramic which is used as a functional material or a structural material is produced through a molding step and a calcination step from a metal oxide powder as a raw material. Properties of the metal oxide powder to be used as the raw material have a large influence on the production steps, and functions and physical properties of the ceramic product. Then, it is highly desired to provide a complex metal oxide powder having powder properties which are precisely controlled so that they are suitable for an intended application.
When a metal oxide powder is used in a dispersed state such as a magnetic fine powder, a filler or a pigment, since properties of each particle are reflected directly on the dispersed state, the control of the properties of the powder is more important.
The required properties of the complex metal oxide powder vary with a kind and application form of the metal oxide. Commonly required properties are a uniform particle size of the metal oxide powder, that is, a narrow particle size distribution, and a weak bond among primary particles, that is, less agglomeration and good dispersibility.
For example, yttrium-aluminum garnet is, in a narrow sense, a complex metal oxide represented by the general formula: Y.sub.3 Al.sub.5 O.sub.12, and in a broad sense, it includes a complex metal oxide in which a part of yttrium elements are replaced by cerium, neodymium, terbium, and the like. The yttrium-aluminum garnet is useful as a mother material in optoelectronics. For instance, single crystal yttrium-aluminum garnet in which a part of yttrium elements are replaced by neodymium is used as a laser oscillator material, and crystalline particles of the yttrium-aluminum garnet in which a part of yttrium elements are replaced by cerium or terbium are used as a fluorescent substance, and so on.
A rare earth element-iron garnet ((R.sub.3 Fe.sub.5 O.sub.12 wherein R is a rare earth element) which is represented by yttrium-iron garnet (Y.sub.3 Fe.sub.5 O).sub.12), or a garnet in which a part of the rare earth element and/or iron are replaced by other metal is useful as a magnetic material of microwave, or a material of a part which uses a magnet-optical effect.
A solid solution of metal compounds, for example, a solid solution of zirconium oxide and an oxide of at least one metal selected from yttrium, magnesium, calcium, cerium and rare earth elements such as scandium and ytterbium is useful as a material to be used in a high temperature resistant material, an ion conductive material, a piezoelectric material, etc. Further, it is used as a raw material of a sintered material or flame spray coating.
Hitherto, these complex metal oxides are produced by a liquid phase method, a solid phase method, a gas phase method, a hydrothermal synthesis method, a flux method, and the like. The produced metal oxide powders have some problems such as formation of agglomerates, a wide particle size distribution of the intended product, removal of impurities, control of a particle size, and so on, and they are not necessarily satisfactory. Further, the above production methods themselves have problems including reaction conditions such as complicated procedures and difficult control, problems of apparatuses, costs of raw materials, and so on. Then, it has been desired to develop a complex metal oxide powder which contains less agglomerated particles and have a narrow particle size distribution, and to develop a method for producing such complex metal oxide powder generally and advantageously in an industrial production.
SUMMARY OF THE INV
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Koike Hironobu
Mohri Masahide
Umeda Tetsu
Langel Wayne
Sumitomo Chemical Company Limited
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