Superconductivity and crystal structure peculiarities of the oxygen deficient YBa/sub 2/Cu/sub 3/O/sub 7-delta/ compounds

Conference · Wed Mar 01 04:00:00 EST 1989 · IEEE Trans. Magn.; (United States)

OSTI ID:6051946

Baryaktar, V G; Mikhailov, I G; Morozovsky, A E; Nemoshkalenko, V V; Pan, V M; Tolpygo, S K; Vasilenko-Sheremetiev, M G; Melnikov, V S; Pshentsova, N P

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-
• Conference Information: Journal Name: IEEE Trans. Magn.; (United States) Journal Volume: 25:2
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
&amp; Refractories-- Structure &amp; Phase Studies
360204* -- Ceramics
Cermets
&amp; Refractories-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
ATOM TRANSPORT
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
HIGH TEMPERATURE
NEUTRAL-PARTICLE TRANSPORT
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
POINT DEFECTS
RADIATION TRANSPORT
STRUCTURAL CHEMICAL ANALYSIS
SUPERCONDUCTIVITY
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
VACANCIES
YTTRIUM COMPOUNDS
YTTRIUM OXIDES