Impurity doping of chemical-vapor-deposited Nb/sub 3/Ge and its effect on critical-current density

Journal Article · Wed Feb 01 04:00:00 EST 1978 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.324652· OSTI ID:5143025

Braginski, A I; Roland, G W; Daniel, M R; Santhanam, A T; Guardipee, K W

In an earlier work, we demonstrated that high self-field and low-field critical-current densitites J/sub c/ of the order of 10/sup 6/ A cm/sup -2/ can be attributed to flux pinning on a dispersed Nb/sub 5/Ge/sub 3/ tetragonal phase present in Nb/sub 3/Ge/sub 3/ layers grown by chemical-vapor deposition (CVD). In this study, we examined the effect of impurity gas additions on J/sub c/ and the critical temperature T/sub c/ of the A15 superconducting phase. The gas impurities were N/sub 2/, C/sub 2/H/sub 6/, and CO/sub 2/. The impurity concentration in the gas phase was varied over three to four orders of magnitude to establish tradeoffs between T/sub c/ deterioration and J/sub c/ enhancement. The x-ray phase analysis of samples containing the highest impurity concentrations indicated by the presence of niobium nitrides and carbides, respectively. The T/sub c/ was affected least by N/sub 2/ and most by CO/sub 2/ additions. Doping by N/sub 2/ or C/sub 2/H/sub 6/ resulted in A15 deposits free of the tetragonal phase and having J/sub c/'s of the order of 10/sup 6/ A cm/sup -2/, comparable to the best Nb/sub 5/Ge/sub 3/-containing samples. The grain size of deposits was estimated from thinned specimens using transmission electron microscopy. Correlation of J/sub c/ with the microstructure of the sample suggested that predominant flux pinning occurs on impurities incorporated in Nb-Ge layers and on the accompanying defects.

• Research Organization: Westinghouse Research and Development Center, Pittsburgh, Pennsylvania 15235
• OSTI ID: 5143025
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 49:2; ISSN JAPIA
• 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
ALKANES
ALLOYS
CARBIDES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
CRITICAL CURRENT
CRYOGENIC FLUIDS
CRYSTAL DOPING
CRYSTAL STRUCTURE
CURRENTS
DEPOSITION
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
ELEMENTS
ETHANE
FLUIDS
GERMANIUM ALLOYS
GRAIN SIZE
HYDROCARBONS
IMPURITIES
MAGNETIC FLUX
MICROSTRUCTURE
NIOBIUM ALLOYS
NIOBIUM BASE ALLOYS
NIOBIUM CARBIDES
NIOBIUM COMPOUNDS
NIOBIUM NITRIDES
NITRIDES
NITROGEN
NITROGEN COMPOUNDS
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PNICTIDES
SIZE
SUPERCONDUCTIVITY
SUPERCONDUCTORS
SURFACE COATING
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
TYPE-II SUPERCONDUCTORS