Abstract:
Three superconducting samples with the composition Bi16Pb0J5r2Ca2Cu3O were prepared using solid state technique. The Bi2O3, PbO, SrCO3 and CuO powders of 99.99% purity were used as starting raw materials. The powders sample were mixed with the nominal cation ratio Bi:Pb:Sr:Ca:Cu = 0.8:0.2:1:1:1.5. After mixing appropriate quantities, the sample were well prepared by dry grinding. Then the powder was divided into three sets and with the labels Sample 1, Sample 2 and Sample 3. Then the samples were calcinated at constant temperature of 820°C and the pallets of diameter 14 mm and of thickness 1-2 mm were prepared under the pressure of 200 kg/cm2, 300 kg/cm2 and 250 kg/cm2. After that the pallets were subjected to preliminary sintering at constant
temperature in the furnace and allowed to furnace cooling to room temperature in air.
The resistance measurements at low temperatures were performed on these samples
using a resistivity probe. The sample 1 shows the onset superconducting transition
temperature Tgmet at 101 K and the sample 2 shows the onset superconducting transition
temperature Tonsel at 112 K. The sample 3 shows the onset superconducting transition
temperature Tonset at 110 K. The XRD measurements also showed the presence of Bi2223 phase in sample 1, the presence of Bi2212 and the Bi2223 phases in the sample 2 and the Bi2223 phase in the sample 3.
