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 (Tc) and transport critical current density (Jc) 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 Tc and Jc were observed for the sample with 0.1 wt.% nano Cr2O3. The variation in the Jc 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 Jc on temperature, the characteristic length (Lc) associated with the pinning force was estimated to be approximately the same as the average grain size in all the samples.