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Synthesis of Superconducting Oxide Powders From Metal Carboxylate Precursors

IP.com Disclosure Number: IPCOM000036873D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

David, LD: AUTHOR

Abstract

This article describes the preparation of fine powders of superconducting oxides which are produced from organometallic or metal-organic precursors by synthesis. A far more homogeneous powder, one having smaller particle size and a lower carbon content, is obtained by application of the disclosed procedures than is otherwise available by use of existing methods.

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Synthesis of Superconducting Oxide Powders From Metal Carboxylate Precursors

This article describes the preparation of fine powders of superconducting oxides which are produced from organometallic or metal-organic precursors by synthesis. A far more homogeneous powder, one having smaller particle size and a lower carbon content, is obtained by application of the disclosed procedures than is otherwise available by use of existing methods.

Superconducting oxides are presently obtained by applying either of two methods, solid-state reaction or co-precipitation. The former method is quicker but often results in phase separation or in the formation of wrong phases, i.e., other compounds, the most common being BaCuO and CuO. The latter method, co-precipitation, typically starts with the nitrate forms of the individual constituents and precipitates them out of solution in their corresponding carbonate forms. The precipitated sludge is then heated to remove water, followed by repeated cycles of reheating, mixing, and grinding (also necessary in the solid-state reaction method) to attain a desired level of powder fines. Neither of the existing methods appear capable of consistently meeting superconducting oxide powder requirements [1]. The disclosed procedures, on the other hand, offer significant improvements in powder homogeneity, stoichiometry, particle size and carbon content level over literature values.

Superconducting oxides of superior purity, particle size and homogeneity have been obtained by mixing stoichiometric ratios of carboxylates of constituent metals together in aqueous solution, boiling the solution dry, then calcining the resultant gel in air, and then again in oxygen. Mixtures of acetates and/or citrates are used to successfully initiate precipitation. A tested recipe for synthesizing a high Tc superconductive oxide powder, YBa2Cu3O7-w, is provided as the basis of the disclosed procedure: A 1:2:3 mole ratio of yttrium (Y), barium (Ba) or

copper (Cu) acetates/citrates is mixed in aqueous

solution, which is subsequently boiled down in air to a

gel. The gel is next calcined in air for...