Microwave surface resistance measurements of air-atomised spray deposited Tl-Ba-Ca-Cu-O thick films

The surface resistance (R/sub s/) of spray pyrolysed Tl/sub 2/Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ thick films on 1 inch diameter finely polished yttria-stabilised zirconia disks has been measured using a TE/sub 011/ mode end-wall-replacement cavity at 20 GHz and 77 K. R/sub s/ values of 5.3 m/spl Omega/ and 1.3 m/spl Omega/ at 20 GHz and 10 GHz (scaled assuming an f/sup 2/ dependence) respectively were obtained. These results are the best recorded R/sub s/ values to date for thick films of any superconductor at the same frequencies and at 77 K. Transport critical current density (J/sub c/) measurements on the films exhibited values of >3/spl times/10/sup 4/ A/cm/sup 2/ at 77 K.<
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