Superconductivity and Range of Existence of the A15 Phase in the Niobium - Germanium System.
Abstract
Niobium-germanium films which remain superconducting up to 22.5 degrees Kelvin were prepared using high rate (33-132 Angstroms per second) electron-beam codeposition. The effect of gas impurities on the stability and structure of the A15 phase was investigated. The presence of oxygen in the deposition chamber during the film condensation was found to be necessary for stabilizing the A15 phase with a high superconducting transition temperature. Analysis of niobium-germanium films showed that oxygen can extend, to a certain limit, the germanium-rich range of the A15 phase with an accompanying decrease in the lattice constant. The effect of different oxygen partial pressure on the A15 phase boundary, the lattice constant, the superconducting transition temperature, width of the transition, and the electrical resistance ratio was also examined.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- July 1976
- Bibcode:
- 1976PhDT........39H
- Keywords:
-
- Physics: Condensed Matter;
- Germanium;
- Niobium;
- Superconductivity;
- Electron Beams;
- Films;
- Impurities;
- Oxygen;
- Transition Temperature;
- Solid-State Physics