Field induced microwave absorption in melt textured and sintered high T-c superconductors

Low and high field dependent microwave absorption is studied in various sin tered and melt textured HTSs. The low field loss is found to originate from weak links and the high field loss is due to thermally assisted flux flow. Melt textured superconductors are found to be best suited for low field de vice applications due to the drastic reduction in low field induced loss wh en compared to sintered samples. Melt textured superconductors with 211 inc lusions are found to show reduced high field losses due to pinning of field at the secondary defects created by 211 particulates. Various parameters o f the critical state such as J(c) and the pinning force constant, K-x, are determined from the microwave absorption study.