Superconducting and Transport Properties of (Bi-Pb)-Sr-Ca-Cu-O with Nano-Cr2O3 Additions

The effect of nano Cr2O3 additions in (Bi, Pb)-Sr-Ca-Cu-O superconductors using the coprecipitation method is reported. Nano Cr2O3 with 0.1, 0.3, 0.5, 0.7, and 1.0 wt.% were added to the (Bi, Pb)-Sr-Ca-Cu-O system. The critical temperature (T c) and transport critical current density (J c) were determined by the four-point probe technique. The phases in the samples were determined using the powder X-ray diffraction method. The microstructure was observed by a scanning electron microscope and the distribution of nano Cr2O3 was determined by energy-dispersive X-ray analysis (EDX). The maximum T c and J c were observed for the sample with 0.1 wt.% nano Cr2O3. The variation in the J c of all the samples was explained by the effective flux pinning by nano Cr2O3 in the samples. Using the self-field approximation together with the dependence of J c on temperature, the characteristic length (L c) associated with the pinning force was estimated to be approximately the same as the average grain size in all the samples.