Grain boundary flux pinning in superconducting niobium
Thesis/Dissertation
·
OSTI ID:5932575
Grain boundary flux pinning in superconducting niobium has been investigated in bicrystals produced by two different techniques, recrystallization and electron beam welding, as well as in polycrystalline foils doped with oxygen. The bicrystals allowed the evaluation of the pinning force from a single grain boundary, eliminating the problem of summing the pinning forces of many grain boundaries which is present in polycrystalline samples. A specific pinning force at a reduced field h= 0.3 of Q/sub GB/ = 470 N/m/sup 2/ was found for a bicrystal with an impurity parameter ..cap alpha.. = 1.5 produced by recrystallization and a Q/sub GB/ = 80 N/m/sup 2/ was found for a bicrystal with an impurity parameter ..cap alpha.. = 0.12 produced by electron beam welding. Grain boundary flux pinning was investigated as a function of purity and temperature in the niobium foils. Impurity parameters ..cap alpha.. from 0.03 to 10 were achieved by annealing the foils at different temperatures from 1300 to 1650/sup 0/ C in low oxygen partial pressures. Grain boundary flux pinning force Q/sub GB/ was 60 N/m/sup 2/ at reduced field h = 0.3. The pinning was measured over the temperature range 1.5 to 4.2 K. From the observed temperature dependence and purity dependence of the specific pinning force, it is concluded that the electron scattering interaction mechanism is the dominant grain boundary flux pinning mechanism in niobium for impurity levels above ..cap alpha.. = 0.03.
- Research Organization:
- Cornell Univ., Geneva, NY (USA)
- OSTI ID:
- 5932575
- Country of Publication:
- United States
- Language:
- English
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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
BICRYSTALS
CRYSTAL DOPING
CRYSTALS
DATA
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON BEAM WELDING
ELEMENTS
ENERGY
EXPERIMENTAL DATA
FABRICATION
FOILS
INFORMATION
JOINING
MAGNETIC FLUX
METALS
NIOBIUM
NONMETALS
NUMERICAL DATA
OXYGEN
PHYSICAL PROPERTIES
POLYCRYSTALS
Q-VALUE
RECRYSTALLIZATION
SUPERCONDUCTIVITY
TEMPERATURE DEPENDENCE
TRANSITION ELEMENTS
WELDING
360104* -- Metals & Alloys-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BICRYSTALS
CRYSTAL DOPING
CRYSTALS
DATA
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON BEAM WELDING
ELEMENTS
ENERGY
EXPERIMENTAL DATA
FABRICATION
FOILS
INFORMATION
JOINING
MAGNETIC FLUX
METALS
NIOBIUM
NONMETALS
NUMERICAL DATA
OXYGEN
PHYSICAL PROPERTIES
POLYCRYSTALS
Q-VALUE
RECRYSTALLIZATION
SUPERCONDUCTIVITY
TEMPERATURE DEPENDENCE
TRANSITION ELEMENTS
WELDING