Microwave surface resistance of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films on polycrystalline alumina and Ni-based alloy substrates with ion-beam-assisted-deposited buffer layers

We measured the microwave surface resistance R/sub s/ of superconducting YBa/sub 2/Cu/sub 3/O/sub 7-x/(YBCO) films on buffered polycrystalline alumina and Ni-based alloy substrates using parallel-plate technique. We observed a strong between the low-power R/sub s/ and the in-plane mosaic spread of the YBCO films. A 0.4-/spl mu/m-thick YBCO film with an in-plane mosaic spread of 6.60 (7/spl deg/) on a buffered polycrystalline alloy (buffered polycrystalline alumina) showed an R/sub s/ of 0.51 m/spl Omega/ (1.89 m/spl Omega/) at 76 K and 0.17 m/spl Omega/ (0.21 m/spl Omega/) at 4 K.