Surface resistance of screen-printed Bi2223 thick films on Ag and dielectric ceramic substrates

Abstract

Surface resistance R/sub s/ of screen-printed (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ thick films on Ag, MgO, and Ba(Sn,Mg,Ta)O/sub 3/ substrates was measured at 10.7 GHz in the temperature range between 20 and 130 K using a dielectric resonator method. For thick films on Ag substrates, it becomes lower than that for a Cu plate as temperature decreases below 100 K, and reaches 1.7 m/spl Omega/ at 77 K and 0.3 m/spl Omega/ at 30 K. The use of MgO or Ba(Sn,Mg,Ta)O/sub 3/ dielectric substrate for film fabrication causes some degradation in the value of R/sub s/, while still being superior to that for a Cu plate below 80 K. From a practical point of view, the (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ thick films were screen-printed on both sides of Ba(Sn,Mg,Ta)O/sub 3/ disk to serve as superconducting electrodes for the dielectric resonator. The unloaded quality factor Q/sub n/ for the resonator at 2.1 GHz on a TM/sub 010/ mode is superior to the same dielectric resonator with Cu electrodes below 90 K. It is 3 times higher than the value for the resonator with Cu electrodes at 70 K and also 5 times higher at 30 K.