Ss. Dubey et al., FLUX-PINNING AND SUPERCONDUCTIVITY IN IN-SITU PREPARED AL-DOPED AND ZN-DOPED CU-NB COMPOSITE WIRES, Journal of physics. D, Applied physics, 27(11), 1994, pp. 2418-2422
The effects of Al and Zn on the critical current density, upper critic
al field and pinning force of in situ prepared Cu-Nb wires have been s
tudied. Doping this system by 1 wt% of these impurities results in a c
hange in critical current density and pinning force. The critical curr
ent density increases at lower fields for both additives but decreases
at high fields. The upper critical field H-C2 shows a decrease for bo
th additives. We have modified the Kramer flux pinning law for these t
wo additives. It is found that the value of n, which is a constant in
the scaling law of Fietz and Webb with a value of 2.5, varies in the c
ase of these additives and does not remain constant.