Ion-channeling study of anomalous atomic displacements at the superconducting transition in high-T sub c materials

Conference · Fri Jun 01 04:00:00 EDT 1990

OSTI ID:6473304

Rehn, L E; Sharma, R P; Baldo, P M

Ion channeling along the (001) direction in high-quality single crystals of (Y/Er)Ba{sub 2}Cu{sub 3}O{sub 7-x} revealed an abrupt change in displacements in the a-b plane of the Cu and O atoms at the superconducting transition, {Tc}; normal Debye-like'' vibrations were found for the Y/Er and Ba atoms. The anomalous change in Cu-O displacements was found to shift directly with stoichiometry-induced changes in {Tc}, implying a direct link between the observed phonon anomaly and the superconducting transition. Recent measurements of ion-channeling along the (001) axis in (Bi{sub 1.7}Pb{sub 0.3})Sr{sub 2}Ca{sub 1}Cu{sub 2}O{sub x} single-crystals revealed a similar change at {Tc}, suggesting that this phonon anomaly is a general feature of high-{Tc} superconductivity. In order to identify more specifically the crystallographic directions and displacement amplitudes associated with the anomalous phonon behavior, axial channeling scans using RBS, as well as characteristic x-ray production, were taken at several temperatures between 30 and 300K along the (301) and (331) directions of YBa{sub 2}Cu{sub 3}O{sub 7-x} single crystals. Twins present in the specimens, and the existing static atomic displacements present along these directions, caused the channeling to be poorer along these axes compared to the (001) direction. Also, a much stronger dependence of the minimum yield on depth was observed. However, since only one twin variant generally dominated over sufficiently wide areas of the specimens, reasonably good ({approximately}10%) minimum yields could be obtained along the appropriate (331) axis, and detwinned crystals produced good results along (301). 22 refs., 5 figs.

• Research Organization: Argonne National Lab., IL (USA)
• Sponsoring Organization: DOE/ER
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6473304
• Report Number(s): CONF-900632-2; ON: DE91004408
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
656100* -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BISMUTH COMPOUNDS
CALCIUM COMPOUNDS
CHALCOGENIDES
CHANNELING
COPPER COMPOUNDS
COPPER OXIDES
ELASTIC SCATTERING
ELECTRON-PHONON COUPLING
ERBIUM COMPOUNDS
HIGH-TC SUPERCONDUCTORS
ION CHANNELING
LEAD COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
RUTHERFORD SCATTERING
SCATTERING
STRONTIUM COMPOUNDS
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
YTTRIUM COMPOUNDS