MELT-TEXTURED YBA2CU3O7 FOR LOW-FIELD APPLICATIONS IN MICROWAVE DEVICES

We report the results of an investigation of microwave power loss at 1 0 GHz in YBCO at 77 K. The samples are melt-textured YBa2Cu3O7 (123) w ith 28 mole % Y2BaCuO5 (211) inclusions and x% of Ag added to bridge t he gaps at the grain boundaries. The sample with 10% Ag shows critical currents > 10(8) amp/m(2) at 77 K. Measurements down to 77 K show tha t microwave power loss drops more sharply (through T-c of 89 K) with h igher Ag content. Dc magnetic-field-induced microwave absorption (MWMA ) recorded at 77 K shows that in these samples the low (similar to 10 mT) field loss is drastically reduced with respect to that in typical YBCO ceramics.