Tsutomu Tatekawa

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

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.

Fabrication and Microwave Operation of Dual-mode Ba(Sn,Mg,Ta)O3 Resonator with Bi2223 Thick Film as Superconductor Electrodes

The TM110 dual-mode microwave resonator was designed and fabricated with screen-printed (Bi,Pb)2Sr2Ca2Cu3Ox thick films and a 25mm-cubic Ba(Sn,Mg,Ta)O3 dielectric ceramic block of relative dielectric constant ɛr=24. The thick films were printed on every six surface of the dielectric block and served repetitive combination processes of cold isostatic pressing and sintering. The typical value of the unloaded quality factor was 40,000 at 1.8GHz, 70K, and the surface resistance of Bi2223 was estimated at 1mΩ.