Progress toward a practical Nb--Ge conductor

Conference · Thu Jan 01 04:00:00 EST 1976

OSTI ID:7324898

Braginski, A. I.; Gavaler, J. R.; Roland, G. W.; Daniel, M. R.; Janocko, M. A.; Santhanam, A. T.

Properties of high-T/sub c/ Nb--Ge films deposited by sputtering and by chemical vapor deposition (CVD) have been investigated. Results of sputtering in the presence of controlled levels of O/sub 2/, N/sub 2/, Si, and of reactive sputtering in Ar--GeH/sub 4/, suggest that the high-T/sub c/ A15 phase is impurity- or defect-stabilized. In CVD deposits two tetragonal modifications were found: sigma and T2, the latter probably stabilized by Cl/sub 2/. High critical current densities, J/sub c/ (H, T) of fine-grained sputtered films are attributed to flux pinning on A15 grain boundaries. In coarse-grained CVD films high self-field J/sub c/'s, 10/sup 6/ to 10/sup 7/ A cm/sup -2/ at T = 4.2/sup 0/K, are attributed to pinning on dispersed sigma-phase. Comparably high J/sub c/'s were also obtained in CVD A15 films doped with impurities. Low field ac losses p (H, T) were correlated with J/sub c/ and coating geometries. The feasibility of fabricating multifilamentary composite conductors by CVD was demonstrated experimentally and a fabrication process for long Nb/sub 3/Ge CVD tapes is being developed.

• Research Organization: Westinghouse Research Labs., Pittsburgh, PA (USA)
• OSTI ID: 7324898
• Report Number(s): COO-2522-6; CONF-760829-45
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104 -- Metals & Alloys-- Physical Properties
360301* -- Composite Materials-- Preparation & Fabrication-- (-1987)
420201 -- Engineering-- Cryogenic Equipment & Devices
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AC LOSSES
ALLOYS
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
COMPOSITE MATERIALS
CRITICAL CURRENT
CRITICAL FIELD
CRYSTAL STRUCTURE
CURRENTS
DEPOSITION
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
FABRICATION
FILMS
GERMANIUM ALLOYS
MAGNETIC FIELDS
NIOBIUM ALLOYS
NIOBIUM BASE ALLOYS
PHYSICAL PROPERTIES
SPUTTERING
SUPERCONDUCTING COMPOSITES
SUPERCONDUCTING FILMS
SUPERCONDUCTIVITY
SURFACE COATING
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE