Reaction pathways in the formation of the Tl--Ca--Ba--Cu superconducting phases
- Department of Chemical Engineering, State University of New York, Buffalo, New York 14260 (US)
The 2223, 1223, 1324, and 1122 phases in the Tl--Ca--Ba--Cu system were prepared from sample mixtures having the same stoichiometry as the final phase. Powder x-ray diffraction analysis was used to follow the formation of these phases at 867 {degree}C for up to 2 h. The formation of the 2223 phase is shown to occur via the sequential transformations 2021{r arrow}2122{r arrow}2223. For the 1-2-2-3 and 1-3-2-4 samples, the sequential transformations 1021{r arrow}2021{r arrow}2122{r arrow}2223 occur before the final 1223 and 1324 phases are obtained. For the 1122 phase the formation is preceded by the 1021{r arrow}2021{r arrow}2122 transformations. Using scanning electron microscopy, a phase with a glassy appearance was detected in many of the reacted samples. This glassy'' phase appears to be a precursor in the formation of the Tl--Ca--Ba--Cu phases.
- OSTI ID:
- 5376222
- Journal Information:
- Journal of Materials Research; (USA), Journal Name: Journal of Materials Research; (USA) Vol. 4:5; ISSN JMREE; ISSN 0884-2914
- Country of Publication:
- United States
- Language:
- English
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ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CALCIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
COHERENT SCATTERING
COPPER COMPOUNDS
COPPER OXIDES
DIFFRACTION
DISPERSIONS
ELECTRON MICROSCOPY
GLASS
MICROSCOPY
MIXTURES
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
POWDERS
SCANNING ELECTRON MICROSCOPY
SCATTERING
STOICHIOMETRY
SUPERCONDUCTORS
SYNTHESIS
THALLIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
VERY HIGH TEMPERATURE
X-RAY DIFFRACTION