[en] Copper rich compounds with YBaCu12O15 stoichiometry were synthesized at 900 deg. C under oxygen rich atmosphere and annealed at 350 deg. C in oxygen flow during 1, 3 and 60 days. Results of AC magnetic susceptibility, thermomagnetic analysis and electron paramagnetic resonance spectroscopy indicate multiphase materials containing the phases YBaCu-123 and YBaCu-247. Critical temperatures were determined by AC magnetic susceptibility and confirmed by EPR measurements
Journal
Journal of Magnetism and Magnetic Materials; ISSN 0304-8853; 
; CODEN JMMMDC; v. 226-230(1-3); p. 309-310
; CODEN JMMMDC; v. 226-230(1-3); p. 309-310
[en] Structural alterations in spent oil shales submitted to thermal treatment, in the temperature range from 1000 C to 10000 C, followed by acid leaching (HCl) were investigated. EPR and Moessbauer spectrometry indicate the synthesis of glass-like structures beginning at 9000 C. Existing coordination sites containing Fe3+ are shown to be efficient probes to this process. (author)
Journal