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Show moreBackground of the invention: This invention pertains to the art of ceramic powder precursors, and more particularly to a method for producing coprecipitated multicomponent oxide powder precursors. The invention is particularly applicable to a method for coprecipitating metal oxalates as precursors for multicomponent oxide powders used in producing ceramics for a variety of applications, acid will be described with particular reference thereto. The invention may be advantageously employed in other environments and applications. The coprecipitation of mixed salts from liquid solutions is a well-established method of ceramic powder precursor synthesis. Coprecipitation refers to the simultaneous precipitation of more than one metal from the same solution. A multicomponent liquid solution of soluble inorganic salts (e.g., metal nitrates, halides, sulfates) is typically combined with a liquid solution of a precipitating agent compound. The precipitating agent is chosen such that, when dissolved and combined with the metals solution, one of its radicals combines with the metal ions to form insoluble salts which thermally decompose to form oxides. The insoluble salts will precipitate in a very finely divided and intimately mixed state. Heating the precipitate decomposes these salts, resulting in a chemically homogeneous, fine oxide powder with high surface area. This powder may then be fabricated into a number of ceramic products using various ceramic fabrication techniques. Examples of such ceramic products include, but are not limited to, electrical or electronic ceramics (integrated circuit substrates, capacitors, piezoelectric transducers, ferroelectric devices, or optical or optoelectronic devices, solid electrolytes, electronically conductive ceramic electrodes, and ceramic superconductors); Magnetic ceramics (magnetic storage media, video or audio tape heads, transformer cores, memory devices or arrays); ceramics used primarily for their strength, hardness and/or chemical stability (refractories; heat exchangers; abrasives; fibers for reinforcement; bulk materials and coatings for protection from heat, oxidation, corrosion, wear, stress, or other physical or chemical changes; catalyst substrates); pigments; and catalysts. The type of precipitate formed depends oil the precipitating agent used. The precipitating agent can be selected from among a variety of compounds including, as examples, hydroxides, carbonates, and oxalates. Although there are advantages and disadvantages to using each of the various types of precipitating agents, precipitated carbonates and hydroxides in many cases tend to be gelatinous thereby difficult to rinse, separate, and filter. As a class, oxalates are generally highly insoluble, and they form particles that are readily filtered from the liquid and easy to handle.
http://www.google.com/patents?vid=USPAT5298654
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Show moreBackground of the invention: This invention pertains to the art of ceramic powder precursors, and more particularly to a method for producing coprecipitated multicomponent oxide powder precursors. The invention is particularly applicable to a method for coprecipitating metal oxalates as precursors for multicomponent oxide powders used in producing ceramics for a variety of applications, and will be described with particular reference thereto. The invention may be advantageously employed in other environments and applications. The coprecipitation of mixed salts from liquid solutions is a well-established method of ceramic powder precursor synthesis. Coprecipitation refers to the simultaneous precipitation of more than one metal from the same solution. A multicomponent liquid solution of soluble inorganic salts (e.g., metal nitrates, halides, sulfates) is typically combined with a liquid solution of a precipitating agent compound. The precipitating agent is chosen such that, when dissolved and combined with the metals solution, one of its radicals combines with the metal ions to form insoluble salts which thermally decompose to form oxides. The insoluble salts will precipitate in a very finely divided and intimately mixed state. Heating the precipitate decomposes these salts, resulting in a chemically homogeneous, fine oxide powder with high surface area. This powder may then be fabricated into a number of ceramic products using various ceramic fabrication techniques. Examples of such ceramic products include, but are not limited to, electrical or electronic ceramics (integrated circuit substrates, capacitors, piezoelectric transducers, ferroelectric devices, or optical or optoelectronic devices, solid electrolytes, electronically conductive ceramic electrodes, and ceramic superconductors); magnetic ceramics (magnetic storage media, video or audio tape heads, transformer cores, memory devices or arrays); ceramics used primarily for their strength, hardness and/or chemical stability (refractories; heat exchangers; abrasives; fibers for reinforcement; bulk materials and coatings for protection from heat, oxidation, corrosion, wear, stress, or other physical or chemical changes; catalyst substrates); pigments; and catalysts. The type of precipitate formed depends on the precipitating agent used. The precipitating agent can be selected from among a variety of compounds including, as examples, hydroxides, carbonates, and oxalates. Although there are advantages and disadvantages to using each of the various types of precipitating agents, precipitated carbonates and hydroxides in many cases tend to be gelatinous thereby difficult to rinse, separate, and filter. As a class, oxalates are generally highly insoluble, and they form particles that are readily filtered from the liquid and easy to handle.
http://www.google.com/patents?vid=USPAT5252314
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Show moreField of the invention: The present invention relates to the synthesis of metal oxide films and, more particularly, to a process for synthesizing metal oxide films from liquid solutions onto ordered organic monolayers. The resulting metal oxide film has a highly uniform packing density and particle size. Background of the invention: The field of thin film ceramics has seen rapid growth in recent years. This activity stems in large part from the attractive and often unique properties that ceramic materials bring to a wide variety of applications, including: thin film ferroelectrics; magnetic recording; multilayer coatings for lenses, windows, and laser optics; hard, corrosion-resistant coatings for optical fibers; filters for electromagnetic radiation; acousto-optic devices; and electrochemical sensors for detection of combustible or hazardous species in gases. Another essential ingredient in these developments has been the growing progress in thin film deposition technology, involving gas phase techniques such as chemical vapor deposition, sputtering, laser ablation, and evaporation. Despite their successes, these deposition techniques have some significant shortcomings. Capital equipment costs can be prohibitively high, especially for large-volume applications. There is considerable art associated with the design of the deposition systems and with the control of the operating parameters (e.g., to correct for differential deposition rates between components in a multicomponent film). The most common techniques still primarily involve line-of-sight deposition, with limited applicability to particulates and to complex surfaces and shapes. Most importantly, achievement of the desired properties often requires that the substrate be heated to significant temperatures (several hundreds of .degree.C.), either during deposition or subsequently, to convert the usually amorphous as-deposited material into a well-ordered crystalline film. This significantly limits the capabilities of thin film deposition technology for many metal and polymeric substrates. When a specific crystallographic orientation of the thin film is desired, the choice of substrate is usually further restricted to a single-crystal material whose surface interatomic spacing closely matches that of the desired crystalline film, enabling epitaxial growth. Liquid phase thin film preparation techniques are also known in the art and involve homogeneous precipitation of colloidal particles or gel solutions which are cast as films onto substrates. These methods include sol-gel, colloidal particle systems, spray pyrolysis, and electroless and electrodeposition. Obstacles are associated with these techniques with respect to thin film formation. Colloidal systems, for example, can have low densities and uncontrolled microstructures as a result of the use of binder phases or the aggregation of colloidal particles.
http://www.google.com/patents?vid=USPAT5545432
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Show moreField of the invention: The present invention relates to the synthesis of metal oxide films and, more particularly, to a process for synthesizing metal oxide films from liquid solutions on to ordered organic monolayers. The resulting metal oxide film has a highly uniform packing density and particle size. Background of the invention: The field of thin film ceramics has seen rapid growth in recent years. This activity stems in large part from the attractive and often unique properties that ceramic materials bring to a wide variety of applications, including: thin film ferroelectrics; magnetic recording; multilayer coatings for lenses, windows, and laser optics; hard, corrosion-resistant coatings for optical fibers; filters for electromagnetic radiation; acousto-optic devices; and electrochemical sensors for detection of combustible or hazardous species in gases. Another essential ingredient in these developments has been the growing progress in thin film deposition technology, involving gas phase techniques such as chemical vapor depositions sputtering, laser ablation, and evaporation. Despite their successes, these deposition techniques have some significant shortcomings. Capital equipment costs can be prohibitively high, especially for large-volume applications. There is considerable art associated with the design of the deposition systems and with the control of the operating parameters (e.g., to correct for differential deposition rates between components in a multicomponent film). The most common techniques still primarily involve line-of-sight deposition, with limited applicability to complex surfaces and shapes. Most importantly, achievement of the desired properties often requires that the substrate be heated to significant temperatures (several hundreds of .degree.C.), either during deposition or subsequently, to convert the usually amorphous as-deposited material into a well-ordered crystalline film. This significantly limits the capabilities of thin film deposition technology for many metal and polymeric substrates. When a specific crystallographic orientation of the thin film is desired, the choice of substrate is usually further restricted to a single-crystal material whose surface interatomic spacing closely matches that of the desired crystalline film, enabling epitaxial growth. Liquid phase thin film preparation techniques are also known in the art and involve homogeneous precipitation of colloidal particles or gel solutions which are cast as films onto substrates. These methods include sol-gel, colloidal particle systems, spray pyrolysis, and electroless and electrodeposition. Obstacles are associated with these techniques with respect to thin film formation. Colloidal systems, for example, have low densities and uncontrolled microstructures as a result of the use of binder phases or the aggregation of colloidal particles. Polymeric sol-gel solutions generate amorphous and porous structures which manifest in low density films.
http://www.google.com/patents?vid=USPAT5352485
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