The authors report neutron irradiation experiments on sputtered NbN films, up to a fluence of 1023 m-2 (E> 0.1 MeV), which prove that NbN films are also extremely radiation-hard high-field superconductors. Both the transition temperatures, Tc, and the normal state resistivities show only small changes with neutron fluence. Concerning the critical current densities, jc, degradations by as much as 30% are observed at low fields, whereas in an intermediate field range (11-15 T), virtually no change of jc is seen, and at high fields (near 20 T), even an increase of jc is found. The latter observation is ascribed to a radiation-induced increase of the upper critical field, Bc2, and to the occurrence of peak effects near Bc2

Films of Tl-Ba-Ca-Cu-O have been made by multi-target magnetron sputtering. The best films show an onset of superconductivity at ≈ 110 K and zero resistance at 96 K. Preliminary X-ray diffraction analysis suggests the films to be predominantly oriented with the c-axis perpendicular to the film surface with the lowest multiple of lattice spacing along the c-axis being ∼ 2.94 nm, consistent with the Tl2Ba2CaCu2Ox (2212) phase.

A variety of sputtered NbN films have been irradiated with reactor neutrons at ambient temperature up to a total fluence of 10/sup 23/ m/sup -2/ (E > 0.1 MeV). Only small decreases of T/sub c/ (4--7%) and moderate increases of /rho//sub n/ (/approximately/25%) are observed. Both of these quantities are difficult to interpret because of the granular nature of the films. The critical current densities have been determined in most cases for magnetic fields up to 20 T. While some degradation (/approximately/30%) of j/sub c/ occurs in the intermediate field range (6--15 T), the high field data show no change of j/sub c/ or even small increases due to the radiation-induced increase of H/sub c2/ and the occurrence of peak effects near H/sub c2/. The present experiments demonstrate unambiguously that NbN is an extremely radiation-hard high-field superconductor. 17 refs., 9 figs., 2 tabs.