Variation of the pinning force with microstructure and with the Ginzburg-Landau parameter in Type II superconductors

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6164020

Javier, P J

The variation of the pinning force with microstructure and with the Ginzburg-Landau parameter is studied for 53 vanadium and vanadium alloy specimens. Vanadium-carbide precipitates are used as pinning centers. The Ginzburg-Landau parameter is varied by alloying the vanadium with small quantities of gallium or niobium. Alloy compositions of V-0.20a/oGa, V-1.05a/oGa, V-2.96a/oGa, and V-4.01a/oNb are used. These yield a range of the Ginzburg-Landau parameter from less than 2 for the pure vanadium specimens, to more than 20 for the V-2.96a/oGa specimens. The pinning force is not described by a universal scaling law for all specimens. The pinning force for a specific reduced magnetic field is determined by the depinning mechanism active at that field. There are at least three depinning mechanisms. Two of these can be identified with the plastic-deformation mechanism and the line-pinning mechanism, which are predicted by Kramer. A previously unidentified depinning mechanism is the prevailing factor in specimens with large pinning centers. The empirical line-pinning force of the specimens varies with the individual precipitate volume cubed times the density of precipitates. The pinning force in the plastic-deformation region varies as the cube-root of the density of precipitates. A dependence on the Ginzburg-Landau parameter squared can be observed for the magnitude of the pinning force for most of the reduced field regions.

• Research Organization: Pennsylvania Univ., Philadelphia (USA)
• OSTI ID: 6164020
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
CRYSTAL STRUCTURE
DEFORMATION
ELEMENTS
GALLIUM ALLOYS
GINZBURG-LANDAU THEORY
MAGNETIC FLUX
METALS
MICROSTRUCTURE
NIOBIUM ALLOYS
SUPERCONDUCTORS
TRANSITION ELEMENTS
TYPE-II SUPERCONDUCTORS
VANADIUM
VANADIUM ALLOYS
VANADIUM BASE ALLOYS