Critical current measurements in YBa/sub 2/(Cu/sub 1-//sub x/Fe/sub x/)/sub 3/O/sub 7-//sub delta/

Journal Article · Wed Feb 15 04:00:00 EST 1989 · J. Appl. Phys.; (United States)

OSTI ID:6565632

Woerdenweber, R; Sastry, G V.S.; Heinemann, K; Freyhardt, H C

The influence of Fe substituted for Cu in YBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/ on the microstructure and the critical properties has been studied. In the concentration regime 0less than or equal toxless than or equal to0.05, the microstructure changes drastically from a twin structure for xless than or equal to0.01 to a microdomain structure for xgreater than or equal to0.02. The average spacing of the twin or domain boundaries varies from approx.90 nm for x = 0 to approx.5 nm for xgreater than or equal to0.02, thus providing an ideal system to test the role of boundary pinning. Large intragranular pinning forces are observed for xless than or equal to0.01 followed by a sudden drop to values approx.20 times smaller for xgreater than or equal to0.02. However, although d/a/sub 0/ (twin-spacing/flux-line lattice parameter) changes drastically from d/a/sub 0/>1 for x = 0 to d/a/sub 0/<1 for xgreater than or equal to0.02, the same field dependence of F/sub p/ is observed for all Fe concentrations, i.e., F/sub p/approx.B/sup 2//sub c//sub 2/b(1-b)/sup 2/. It is, therefore, concluded that the twin boundaries are not significantly contributing to the flux pinning and that the decrease in F/sub p/ for 0.01less than or equal toxless than or equal to0.02 is related to the decrease of the upper critical field B/sub c//sub 2/, which is caused by a strong reduction of the electron density of states at the Fermi surface.

• Research Organization: Institut fuer Metallphysik, Hospitalstr. 3/5, D-3400 Goettingen, Federal Republic of Germany
• OSTI ID: 6565632
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 65:4; ISSN JAPIA
• 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
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER
COPPER COMPOUNDS
COPPER OXIDES
CRITICAL CURRENT
CRYSTAL STRUCTURE
CURRENTS
DATA
ELECTRIC CURRENTS
ELEMENTS
EXPERIMENTAL DATA
GRAIN BOUNDARIES
INFORMATION
IRON
IRON COMPOUNDS
IRON OXIDES
MAGNETIC FLUX
METALS
MICROSTRUCTURE
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES