Ceramic composition
AssigneeW. R. Grace & Co.-Conn.
InventorsNicholas D. Spencer, Leonard E. Dolhert
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Abstract
Improved process for making Tl-Ca-Ba-Cu oxide superconductors. A solution of the nitrated of Ca, Ba, and Cu is reacted with a quaternary ammonium carbonate in a slurry (heel) of Tl.sub.2 O.sub.3. Carbonates of Ca, Ba, and Cu precipitate homogeneously on the Tl.sub.2 O.sub.3 particles. Solids are recovered, dried, and heated to make a superconductor. The method minimizes introdution of contaminants. Novel compositions result.
Claims23
Aqueous slurry, the solids of which comprise particles of water-insoluble nuclei of alumina, T1.sub.2 O.sub.3, or T1 metal coated with co-precipitated carbonates of X.sub.b -Z.sub.c -Cu.sub.d where X and Z are different alkaline earth metals, b is 0-10 and c and d independently have a value within the range of 0.1-10.
Composition consisting essentially of carbonates of Ca, Ba, and Cu co-precipitated on particles of alumina, T1.sub.2 O.sub.3 or T1 metal.
Process comprising reacting an aqueous solution of the soluble salts of Cu and of at least one alkaline earth metal, the salts being present to provide an atomic ratio of X.sub.b -Z.sub.c -Cu.sub.d where X and Z are different alkaline earth metals, b is 0-10 and c and d independently have a value within the range 0.1-10 with a solution of quaternary ammonium carbonate in a heel of an aqueous dispersion of particles of water-insoluble nuclei of alumina, T1.sub.2 O.sub.3, or T1 metal so as to form a co-precipitate of carbonate on the nuclei, and recovering and drying the resulting solids.
Process comprising;
- (A) preparing a pre-mix comprising dissolving nitrates of Ca, Ba, and Cu in water in amounts to provide atomic ratios of Ca.sub.b -Ba.sub.c -Cu.sub.d, where b and c are about 0.5-3, and d is about 1-4
- (B) preparing a heel comprising particles of T1.sub.2 O.sub.3 dispersed in water, about1-5 weight % T1.sub.2 O.sub.3 ;
- (C) adding an aqueous solution of quaternary ammonium carbonate to (B) and simultaneously adding (A) to (B), both at controlled addition rate so as to co-precipitate the carbonates of Ca, Ba, and Cu onto the T1.sub.2 O.sub.3 particles without introducing any substantial stoichiometric excess of (A) or quaternary ammonium carbonate;
- into (B);
- while maintaining a pH of about 9-10 in the reaction solution;
- (D) recovering and drying the resulting solids;
- and
- (E) calcining the solids of (D) to form a superconductor.
Dependencies are inferred from the claim text.