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YBa2Cu3O7-δδδδ:Li SUPERCONDUCTOR SYSTEM INVESTIGATED BY DIRECT MICROWAVE ABSORPTION METHOD

M. Velter-Stefanescu1,* , O. G. Duliu2, V. Sandu1

Affiliation

  1. National Institute of Materials Physics, Magurele, P.O. Box MG-7, RO-077125 Bucharest, Romania
  2. University of Bucharest, Department of Atomic and Nuclear Physics, Magurele, P.O. Box MG-11, RO-077125 Bucharest, Romania

Abstract

The influence of thermal neutrons irradiation at different fluencies on the superconductivity properties of Li (2 at. %) doped YBa2Cu3O7−δ system has been investigated by direct microwave absorption method. We have noticed changes of the superconducting properties of the 123 phase that depend on the neutron fluency. By increasing fluency, initially, the phase structure supports a disordering, then a re-ordering accompanied by a significant increase of the average critical temperature Tc to 85.7 K and finally we observed a degradation of the 123 the phase accompanied by a diminishing of Tc. The intragranular dephasing magnetic field Bd, i.e. the direct microwave absorption (DMA) parameter associated with the magnetic field dependence of the critical current density exhibited an opposite tendency, initially decreasing and then increasing at a value close to those of unirradiated samples. We also noticed only on the irradiated samples the presence of a flatness of the DMA curves around 0.5 T, consistent with the expression of a peak effect..

Keywords

Y-Ba-Cu-O high temperature superconductor, Direct microwave absorption method.

Submitted at: Dec. 20, 2004
Accepted at: March 23, 2005

Citation

M. Velter-Stefanescu, O. G. Duliu, V. Sandu, YBa2Cu3O7-δδδδ:Li SUPERCONDUCTOR SYSTEM INVESTIGATED BY DIRECT MICROWAVE ABSORPTION METHOD, Journal of Optoelectronics and Advanced Materials Vol. 7, Iss. 2, pp. 973-977 (2005)