Mangetic Shielding properties of superconducting Y-Ba-Cu-O films on Ni foils

The Y-Ba-Cu-O(YBCO) films were consisted of the highly c-axis oriented Y 1 Ba 2 Cu 3 O x . The T c (R=0) of the films is 70-75 K. A field attenuation ratio of 10 4 (or 80 dB) at 4.2 K and low magnetic field can be obtained. The magnetic shielding effectiveness of the films is significantly affected by the film morphologies, porosites and microcracks in the films