Thin-film high T c superconductors prepared by a simple flash evaporation technique

Thin films of Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O have been deposited on single-crystal MgO substrates by a simple flash evaporation technique. Small pellets of the superconducting compound were formed by standard techniques, then evaporated to completion on the MgO substrates using an electron beam. The best films show an onset of superconductivity at approximately 110 K and zero resistance by 78 K. X-ray diffraction measurements show the films to be tetragonal with nominal lattice parameters of a=3.85 Å and c=30.66 Å. The x-ray data also show the films to be highly textured with the metal-oxide planes parallel to the substrate surface.