Influence of Ag2O addition on thermal conductivity of (Nd–Eu–Gd)Ba2Cu3Oy

Abstract

Abstract The influence of the Ag 2 O addition on the thermal conductivity κ of (Nd–Eu–Gd)Ba 2 Cu 3 O y melt-textured superconductors with several amounts of NEG-211 phase has been studied. The concentration of added Ag 2 O is up to 20 wt.%. The distribution of Ag was observed by back electron image. The critical current density evaluated from a magnetization measurement increases with Ag 2 O at higher magnetic field, which suggests the precipitation of light rare earth (LRE)-rich fine clusters. It was found that the thermal conductivity below T c might be determined by the phonon scattering by the LRE-rich fine clusters, which suppress the enhancement of κ , and by the improvement of the crystallographic quality with Ag-doping, by which the enhancement is recovered. In almost all of the samples we measured the latter was dominant. The suppression of κ by the magnetic field H was observed below 110 K. The ratio of κ ( H )/ κ ( H =0) is almost independent of the amount of Ag 2 O content.