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Title: Rapid formation of phase-clean 110 K (Bi-2223) powders derived via freeze-drying process

A process for the preparation of amorphous precursor powders for Pb-doped Bi.sub.2 Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.x (2223) includes a freeze-drying process incorporating a splat-freezing step. The process generally includes splat freezing a nitrate solution of Bi, Pb, Sr, Ca, and Cu to form flakes of the solution without any phase separation; grinding the frozen flakes to form a powder; freeze-drying the frozen powder; heating the dried powder to form a dry green precursor powders; denitrating the green-powders; heating the denitrated powders to form phase-clean Bi-2223 powders. The grain boundaries of the 2223 grains appear to be clean, leading to good intergrain contact between 2223 grains.
Inventors:
 [1]
  1. (Hinsdale, IL)
Issue Date:
OSTI Identifier:
870443
Assignee:
United States of America as represented by United States (Washington, DC) ANL
Patent Number(s):
US 5523285
Contract Number:
W-31109-ENG-38
Research Org:
Argonne National Laboratory (ANL), Argonne, IL
Country of Publication:
United States
Language:
English
Subject:
rapid; formation; phase-clean; 110; bi-2223; powders; derived; via; freeze-drying; process; preparation; amorphous; precursor; pb-doped; sr; cu; 2223; incorporating; splat-freezing; step; splat; freezing; nitrate; solution; pb; form; flakes; phase; separation; grinding; frozen; powder; heating; dried; dry; green; denitrating; green-powders; denitrated; grain; boundaries; grains; appear; clean; leading; intergrain; contact; nitrate solution; phase separation; grain boundaries; precursor powder; precursor powders; drying process; dried powder; freeze-drying process; /505/252/