Copper rich Y-Ba-Cu-O superconductors

Copper rich compounds with YBaCu12O15 stoichiometry were synthesized at 900 degreesC under oxygen rich atmosphere and annealed at 350 degreesC in oxyg en flow during 1, 3 and 60 days. Results of AC magnetic susceptibility, the rmomagnetic analysis and electron paramagnetic resonance spectroscopy indic ate multiphase materials containing the phases YBaCu-123 and YBaCu-247. Cri tical temperatures were determined by AC magnetic susceptibility and confir med by EPR measurements. (C) 2001 Elsevier Science B.V. All rights reserved .