Metastable metallic superconductors with high transition temperatures and composite superconductors. Final report 1 Jan 74--31 Dec 77

Technical Report · Sat Dec 31 04:00:00 EST 1977

OSTI ID:6697539

Gavaler, J R; Daniel, M R

Chemical vapor deposition (CVD) was found to be a practical method for preparing large quantities of Nb-Ge. The fabrication of Nb-Ge multifilamentary and tape conductors by this method was shown to be feasible. CVD Nb-Ge had critical temperatures and upper critical fields comparable to the sputtered material. Critical-current densities were lower. Second-phase doping was shown effective toward improving current-carrying capacity. A new Nb-Ge growth method (reactive sputtering of niobium in Argon/Germane) was demonstrated and its applicability for use in a magnetron sputtering system evaluated. A study of the effect of impurities (oxygen, nitrogen and silicon) on sputtered Nb-Ge films indicated that each of these impurities can stabilize the high-critical temperature metastable A15 phase. An investigation of the bronze diffusion process illustrated why A15 Nb-Ge cannot readily be made by this method. The formation of A15 Nb-Ga by bronze diffusion was achieved. The preparation of superconducting niobium and A15 structure Nb-Sn was accomplished by liquid sodium reduction of the halides. The anomalously high upper critical field of sputtered NbN film was shown to be due to a surface critical field.

• Research Organization: Westinghouse Electric Corp., Pittsburgh, PA (USA). Research and Development Center
• OSTI ID: 6697539
• Report Number(s): AD-A-050055
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
360104 -- Metals & Alloys-- Physical Properties
360201 -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOY SYSTEMS
ALLOYS
BINARY ALLOY SYSTEMS
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
CRITICAL CURRENT
CRITICAL FIELD
CRYSTAL DOPING
CURRENTS
DEPOSITION
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
ELEMENTS
FABRICATION
GALLIUM ALLOYS
GERMANIUM ALLOYS
IMPURITIES
MAGNETIC FIELDS
METALS
NIOBIUM
NIOBIUM ALLOYS
NIOBIUM COMPOUNDS
NIOBIUM NITRIDES
NITRIDES
NITROGEN COMPOUNDS
PHYSICAL PROPERTIES
PNICTIDES
REFRACTORY METALS
SUPERCONDUCTIVITY
SURFACE COATING
THERMODYNAMIC PROPERTIES
TIN ALLOYS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TRANSITION TEMPERATURE