Resistance fluctuations in the Y-Ba-Cu-O-F system

Journal Article · Wed Jun 01 04:00:00 EDT 1988 · Appl. Phys. Commun.; (United States)

OSTI ID:6225465

Sheng, Z Z; Kiehl, W; Marsh, D; Mooney, D; Arammash, F; Ali, A E; Hermann, A M; Austin, M W; Ledbetter, H

Two batches of samples with nominal composition of YBa/sub 2/Cu/sub 3/O/sub 6.5-X/F/sub 2X/ (x=0-2) were prepared. All fluorine-containing samples were multiphase. Resistance-temperature relationships of these samples depended strongly on their fluorine content and their preparation conditions. Resistance-temperature anomalies were observed for some samples with large values of x. Combining transport measurements with x-ray power diffraction data, the authors attribute these anomalies either to existence of high temperature superconductive phase(s) in the Y-Ba-Cu-O-F system, or to resistance fluctuations resulting from the presence of multiple phases. After the discovery of 90 K superconductors in Y-Ba-Cu-O system (1), superconductors with even higher transition temperatures have been actively sought. Trace superconductivity at 240 K was reported in Y-Ba-Cu-O system by means of the reverse Josephson effect (2), and irreproducible zero resistance at 230 K was claimed in the same system (3). Ovshinsky et al. (4) reported zero resistance at 155 K in one sample with a nominal composition of YBa/sub 2/Cu/sub 3/O/sub 5.5+y/F/sub 2/. The authors have prepared a series of samples of Yba/sub 2/Cu/sub 3/O/sub 6.5/minus/x/F/sub 2x/ (x=0-2). They report here the resistance-temperature data and x-ray powder diffraction data for these samples. They observed resistance anomalies for some samples with high value of x. However, they can not conclude, with certainty that the anomalies result from superconductivity.

• Research Organization: Univ. of Arkansas, Fayetteville (USA)
• OSTI ID: 6225465
• Journal Information: Appl. Phys. Commun.; (United States), Journal Name: Appl. Phys. Commun.; (United States) Vol. 8:2; ISSN APCOD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COHERENT SCATTERING
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL STRUCTURE
DATA
DIFFRACTION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
EXPERIMENTAL DATA
FLUORINE COMPOUNDS
HALOGEN COMPOUNDS
INFORMATION
NUMERICAL DATA
OXIDES
OXYFLUORIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SCATTERING
SUPERCONDUCTIVITY
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION
YTTRIUM COMPOUNDS
YTTRIUM OXIDES