Reaction pathways for the formation of the YBa/sub 2/Cu/sub 3/O/sub 7-//sub x/ compound
The kinetics of the reactions that lead to the formation of YBa/sub 2/Cu/sub 3/O/sub 7-//sub x/ cas investigated starting from various powder mixtures containing different reactants as sources of Ba, Cu, and Y (BaCO/sub 3/, BaO, CuO, Y/sub 2/O/sub 3/, Y/sub 2/Cu/sub 2/O/sub 5/, and BaCuO/sub 2/). These powders were calcined at 940 /sup 0/C for various time intervals. Quantitative x-ray analysis was used to determine the relative amounts of compounds present in the calcined powders. When BaCO/sub 3/ was used as the source of barium, long calcination times were required to obtain the single phased YBa/sub 2/Cu/sub 3/O/sub 7-//sub x/, because of the slow decomposition of BaCO/sub 3/. This leads to large particles and broad particle size distributions and hence to a lower density of the sintered superconducting pellets. Procedures to attain high density superconducting material are identified on the basis of the kinetic studies. Each of them isolates the slow reaction in a first step and prepares the superconducting material via a rapid reaction in a second step. The kinetic studies reveal the reaction mechanisms that were followed in different cases.
- Research Organization:
- Department of Chemical Engineering, State University of New York--Buffalo, Buffalo, New York 14260
- OSTI ID:
- 6183368
- Journal Information:
- J. Mat. Res.; (United States), Journal Name: J. Mat. Res.; (United States) Vol. 4:2; ISSN JMREE
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
COPPER COMPOUNDS
COPPER OXIDES
DISPERSIONS
FABRICATION
KINETICS
MIXTURES
OXIDES
OXYGEN COMPOUNDS
PARTICLE SIZE
PELLETS
POWDERS
REACTION KINETICS
SINTERING
SIZE
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS