Defects in YBCO relevant for RF superconductivity: T-, f- and H-dependencies

The present understanding of intrinsic and extrinsic MTS-properties gained in the last years is applied to sintered and epitaxially grown YBCO. As res ults, the mean free path 1 increases rapidly below T-c, whereas the weak li nks with critical Josephson current j(CJ)(T) and leakage current resistance R-bl describe R(T < 0.8 T-c, f, H) congruent to R-res(T, f, H) over seven orders of magnitude in j(cJ) with j(CJ)R(bl)(2) congruent to 10(-12) A Ohm( 2) cm(2).