Superconductivity in NbGe/sub 2/ and isostructural C-40 compounds
The superconductivity of NbGe/sub 2/ and isostructural C-40 compounds has been studied in a quantitative manner. We have ruled out various mechanisms, such as excitonic superconductivity and filamentary superconductivity, which were originally believed to be responsible for the superconductivity in NbGe/sub 2/. The high transition temperature (T/sub c/ = 16 K) exhibited by sputtered films of NbGe/sub 2/ are shown to be an intrinsic property of the compound and are attributed to the degree of order produced during the formation process. It has also been shown that different sample preparation techniques lead to different values of the superconducting transition temperature, illustrating that the higher transition temperatures could be associated with a higher degree of order produced in the system. The role of excess germanium and thermal effects are also discussed for NbGe/sub 2/. A study of the binary compounds of the hexagonal C-40 system consisting of the members CrSi/sub 2/, VSi/sub 2/, NbGe/sub 2/, NbSi/sub 2/, TaGe/sub 2/, TaSi/sub 2/, and HfSn/sub 2/ shows that four members exhibit superconductivity. Those that showed superconductivity were NbGe/sub 2/ (T/sub c/ = 16K), NbSi/sub 2/ (T/sub c/ = 2.9K), TaSi/sub 2/ (T/sub c/ = 4.4K), and TaGe/sub 2/ (T/sub c/ = 2.7K). One of the major conclusions established through this study is that a new crystal structure type, namely the hexagonal C-40 system is superconducting. It also appears that the explanation for the appearance of superconductivity in some of these compounds is related to the degree of order present in the system which is brought about by the fabrication technique.
- Research Organization:
- Rochester Univ., NY (USA)
- OSTI ID:
- 6231613
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CHROMIUM SILICIDES
SUPERCONDUCTIVITY
GERMANIUM COMPOUNDS
HAFNIUM COMPOUNDS
NIOBIUM COMPOUNDS
NIOBIUM SILICIDES
TANTALUM COMPOUNDS
TANTALUM SILICIDES
TIN COMPOUNDS
VANADIUM SILICIDES
CRYSTAL STRUCTURE
EXPERIMENTAL DATA
TRANSITION TEMPERATURE
CHROMIUM COMPOUNDS
DATA
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
INFORMATION
NUMERICAL DATA
PHYSICAL PROPERTIES
SILICIDES
SILICON COMPOUNDS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS
360104* - Metals & Alloys- Physical Properties
656102 - Solid State Physics- Superconductivity- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena- (-1987)