Transport and magnetic properties of Bi(Pb)2212 superconducting ceramics doped by low rate of potassium

Samples of Bi_1.5Pb_0.5(Sr_1.8−xK_x)CaCu₂O_8+d and Bi_1.5Pb_0.5Sr_1.8CaCu₂O_8+dK_x have been prepared from powders of carbonates and primary oxides using the solid state reaction method and compared in this study. In the first case, potassium (K) is substituted in the strontium (Sr) site. In the second one, K is added. A part of the paper is devoted to discuss the results obtained by X-ray diffraction (XRD) analysis and scanning electron microscope (SEM) observations of (Bi,Pb)₂Sr_1.8CaCu₂O_8+d samples doped by potassium to provide additional microstructural information related to the doping method. These analyses are supplemented by resistivity and magnetic measurements. Results show how the rate of doping by potassium affects transport and magnetic properties of Bi(Pb)2212 phase. The critical current density (J_c) is improved using the two methods and it reaches a double value by the addition of K as compared to the undoped sample.