Microstructures and critical current density of filamentary Eu–Ba–Cu–O with Zr and Zn additions

Abstract

The effect of Zr and Zn doping on superconducting properties and microstructures of filamentary Eu–Ba–Cu–O superconductors prepared by a solution spinning method has been investigated. Samples doped with small amounts of Zr and Zn showed relatively high Jc values of around 2×104Acm−2 at 77K and 0T, which was two times larger than that of the pure Eu123 filament. The temperature range for the partial melting in reduced oxygen partial pressure obtained the Jc value higher than 104Acm−2 at 77K became wider when Zr and Zn were added. From the SEM observation, a small amount of Zr and Zn doping was found to be useful to reduce the size of Eu211 particles, whereas it showed adverse effects on the dispersion of Eu211 particles and compositional homogeneity in a Eu123 matrix. In the case of Zn doping, although sample showed high Jc value larger than 104Acm−2 at magnetic field lower than 2T, a Jc value monotonically decreased at above 3T and superconductivity was disappeared at 11T. On the contrary, in spite of the fact that a Jc value of sample with 0.5at.% Zr decreased by applying only a magnetic field of 0.2T, superconductivity could be maintained up to 17T at 77K.