PHENOMENON OF SUPERCONDUCTIVITY.
Final rept. 16 Mar 66-15 Mar 67 on Phase 2,
RCA LABS PRINCETON NJ
Pagination or Media Count:
For the first time chemical thinning techniques applied to Nb3Sn single crystals have permitted electron micrographic identification of netutron damage in Nb3Sn as an array of spots. Irreversible magnetization measurements on neutron-irradiated single crystals have been analyzed to obtain critical current densities. These measurements indicate an increase in the critical current and in alpha, the pinning force constant, with increased spot density. X-ray examination of neutron-irradiated Nb3Sn has revealed a lattice expansion which increases with neutron dosage. Such an expansion is probably due to the introduction of clusters of vacancies in the disordered lattice. Thus, the kinetics of vacancy annealing can easily be studied. Susceptibility measurements have been made on Nb3Sn crystals as a function of temperature. The susceptibility has an anomaly in the neighborhood of 40 K which must be associated with the lattice transformation in Nb3Sn. These results complement specific heat measurements and should provide information concerning the high T of Nb3Sn. Analysis of specific heat data has been made to extract information concerning the phonon spectrum in Nb3Sn. This analysis indicates that the lattice softening observed in ultrasonic measurements must be confined to the lower phonon frequencies. Reversible magnetization curves have been obtained on single-crystal Nb3Sn near T. These measurements have permitted the first unambiguous determination of the Ginzburg-Landau parameter. Magnetization measurements on the Nb-Ta alloy system have also been made.
- Electricity and Magnetism