Superconductivity and crystal structure peculiarities of the oxygen deficient YBa/sub 2/Cu/sub 3/O/sub 7-delta/ compounds
Crystal structure peculiarities, oxygen atom and vacancy ordering and superconducting properties of YBa/sub 2/Cu/sub 3/O/sub 7-delta/ compounds were investigated for oxygen deficiency range 0 < delta < 0,8. It was shown that orthorhombic to tetragonal phase transition and oxygen atom ordering process are quite different phenomena which appeared to be observed at different temperature ranges. Oxygen disordering in z = 0 plane is thermally activated and occurs mainly at low temperatures, when oxygen depletion is negligibly small. Strong oxygen depletion by heating above 400/sup 0/C leads to the significant local reduction of the negative charge at the z = 0 plane. To restore a charge balance in YBa/sub 2/Cu/sub 3/O/sub 7-delta/ lattice negative (01) and positive (Ba, Cu2, Y) ions have to be driven to shift along z-axis in the opposite directions. These structure changes causes an increase in the unit cell c parameter and in the distances between Cu1-04-05 and Cu2-02-03 layers. Superconducting transition temperature T/sub c/ of YBa/sub 2/CFu/sub 3/O/sub 7-delta/ appears to decrease along with delta increasing. T versus delta dependence has two-step-like shape. The first T/sub c/ drop at small delta values likely can be explained by disordering driven by Cu-O chain destruction. The second one probably is connected with free carrier concentration lowering and weakening of interaction between Cu-O layers.
- Research Organization:
- The Institute of Metal Physics, 36 Vernadsky St., Kiev (SU); The Institute of Geochemistry and Mineral Physics, Kiev (SU)
- OSTI ID:
- 6051946
- Report Number(s):
- CONF-880812-
- Journal Information:
- IEEE Trans. Magn.; (United States), Vol. 25:2; Conference: Applied superconductivity conference, San Francisco, CA, USA, 21 Aug 1988
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BARIUM OXIDES
SUPERCONDUCTIVITY
COPPER OXIDES
OXYGEN
VACANCIES
YTTRIUM OXIDES
ATOM TRANSPORT
CRYSTAL STRUCTURE
HIGH TEMPERATURE
PHASE TRANSFORMATIONS
STRUCTURAL CHEMICAL ANALYSIS
TEMPERATURE DEPENDENCE
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
CRYSTAL DEFECTS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
NEUTRAL-PARTICLE TRANSPORT
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POINT DEFECTS
RADIATION TRANSPORT
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties
360202 - Ceramics
Cermets
& Refractories- Structure & Phase Studies
656100 - Condensed Matter Physics- Superconductivity