Microwave surface resistance of bulk Tl-Ba-Ca-Cu-O superconductors

Abstract

The first measurements of the microwave surface resistance at 18 GHz of bulk Tl-Ba-Ca-Cu-O superconductors produced by the hot isostatic pressing (HIP) process are reported. The superconducting samples, prepared by solid-state reaction with subsequent sintering and consolidation to obtain ideal density, were measured by replacing the end wall of a TE011 circular mode gold-plated copper cavity with the sample and determining the cavity Q for the temperature range 4–300 K. Results indicated that HIP samples which underwent subsequent annealing exhibit, below the critical temperature, a surface resistance approaching an order of magnitude less than copper.