Superconductor precursor mixtures made by precipitation method

• US 4,839,339 A
• Filed: 02/25/1988
• Issued: 06/13/1989
• Est. Priority Date: 02/25/1988
• Status: Expired due to Term

• Current Assignee: Sandia Corporation (Martin Marietta Corporation)
• Original Assignee: United States Department of Energy
• Inventors: Bunker, Bruce C., Voigt, James A., Lamppa, Diana L.
• Primary Examiner(s): Albrecht, Dennis
• Assistant Examiner(s): Krasnow, Ron
• Application Number:
  US07/160,443
• Time in Patent Office: 474 Days
• Field of Search: 423/593, 423/263, 501/123, 501/152, 505/1, 505/809, 505/810, 505/815, 252/518, 252/521
• US Class Current: 505/510
• CPC Class Codes: C01B 13/363 Mixtures of oxides or hydroxides by precipitation
• CPC Class Codes: C01G 3/006 Compounds containing, besides copper, two or more other elements, with the exception of oxygen or hydrogen
• CPC Class Codes: C01P 2002/02 Amorphous compounds
• CPC Class Codes: C01P 2002/60 Compounds characterised by their crystallite size
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2004/50 Agglomerated particles
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: Y10S 505/809 Ceramic
• CPC Class Codes: Y10S 505/81 Compound
• CPC Class Codes: Y10S 505/815 Process of making per se

Abstract

Method and apparatus for preparing highly pure homogeneous precursor powder mixtures for metal oxide superconductive ceramics. The mixes are prepared by instantaneous precipitation from stoichiometric solutions of metal salts such as nitrates at controlled pH'"'"'s within the 9 to 12 range, by addition of solutions of non-complexing pyrolyzable cations, such as alkyammonium and carbonate ions.

Claims

1. A method for preparing a precursor powder which can be calcined to form a superconducting ceramic, said method comprising:

(a) forming an aqueous solution of metal salts composed of the metals that will constitute part of the ceramic and of pyrolyzable counter anions, said metal salts being present in the stoichiometric proportions necessary to form said ceramic;

(b) forming an aqueous solution comprising a lower alkylammonium hydroxide and carbonate anions;

(c) instantaneously and completely mixing said solutions together at pH'"'"'s within the range of 9 to 12 under controlled pH conditions and in quantities that will yield the precursor powder with the exact cation ratios required for the final superconducting ceramic; and

(d) collecting the resulting precipitated precursor powder which consists of the desired superconductor cations, hydroxide and carbonate anions, and minor quantities of pyrolyzable counter ions.

2. A method for preparing a precursor powder which can be calcined to form a superconductor ceramic, said method comprising:

(a) forming an aqueous solution of salts bf yttrium, barium, and copper in molar proportions substantially equal to 1;

2;

3 with a pyrolyzable counter anion;

(b) forming a precipitating anion solution consisting of a stoichiometric quantity of an about 0.5 aqueous tetramethylammonium hydroxide containing about 0.14 M carbonate ions and 0.2 molar aqueous oxalic acid;

(c) instantaneously and completely mixing said solutions together at a pH within the range of 9 to 12 under controlled pH conditions; and

(d) collecting the resulting precipitated precursor powder, which consists of the desired superconductor cations, the pyrolyzable precipitating anions, and minor quantities of pyrolyzable counter ions.