Abstract: The effect of nano Co3O4 addition on the
superconducting properties of (Bi, Pb)-2223 system was studied. The
samples were prepared by the acetate coprecipitation method. The
Co3O4 with different sizes (10-30 nm and 30-50 nm) from x=0.00 to
0.05 was added to Bi1.6Pb0.4Sr2Ca2Cu3Oy(Co3O4)x. Phase analysis by
XRD method, microstructural examination by SEM and dc electrical
resistivity by four point probe method were done to characterize the
samples. The X-ray diffraction patterns of all the samples indicated
the majority Bi-2223 phase along with minor Bi-2212 and Bi-2201
phases. The volume fraction was estimated from the intensities of Bi-
2223, Bi-2212 and Bi-2201 phase. The sample with x=0.01 wt% of
the added Co3O4 (10-30 nm size) showed the highest volume fraction
of Bi-2223 phase (72%) and the highest superconducting transition
temperature, Tc (~102 K). The non-added sample showed the highest
Tc(~103 K) compared to added samples with nano Co3O4 (30-50 nm
size) added samples. Both the onset critical temperature Tc(onset)
and zero electrical resistivity temperature Tc(R=0) were in the range
of 103-115 ±1K and 91-103 ±1K respectively for samples with added
Co3O4 (10-30 nm and 30-50 nm).