Effects of K doping on structural and superconducting properties of Bi[sub 1.5]Pb[sub 0.5]Sr[sub 1.8]CaCu[sub 2]O[sub 8+δ] compounds

Two kinds of potassium doped Bi(Pb)2212 samples are used to investigate the effect of doping the Bi(Pb)2212 ((Bi,Pb)(2)Sr2CaCu2O8) phase by potassium (K): In the first one K is substituted on the Sr site; In the second one K is added. Using the solid state method reaction samples of Bi1.5Pb0.5(Sr1.8-xKx)CaCu2O8+d and Bi1.5Pb0.5Sr1.8CaCu2O8+dKx (0 <= x <= 0.05) have been prepared from powders of carbonates and primary oxides having purity over 99%. The samples have been characterized by X ray diffraction (XRD). scanning electron microscopy (SEM) and resistivity versus temperature measurements. Results show how the kind and the rate of doping by potassium affects the structural and transport properties of Bi(Pb)2212 phase.