Irreversible fields Birr of melt-processed (Sm, Eu, Gd)Ba 2Cu3O7-δ bulk superconductors with varying (Sm, Eu, Gd)2BaCuO5 concentrations have been measured with pulsed magnetic fields up to 28 T in a temperature range from 55 to 85 K. The temperature dependence of Birr was studied by taking account of the effect of heat generation. In comparison with that including 5 mol% (Sm, Eu, Gd)2BaCuO5 phase the samples with 40 mol% (Sm, Eu, Gd)2BaCuO5 inclusion displayed a lower B irr value for temperatures above 75 K, while Birr was enhanced below 75 K. TEM observation unveiled a sharp contrast between a uniform nano-scaled compositional modulation in compositions with 40% (Sm, Eu, Gd)2BaCuO5 inclusion and an inhomogeneous distribution with very low (Sm, Eu, Gd)2BaCuO5 concentration. The present result could thus be understood in the context of different defect states induced by locally compositional fluctuation.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)
- Condensed Matter Physics
- Electronic, Optical and Magnetic Materials