Properties of Ag-Doped Bi_{(1.6)}Pb_{(0.4)}Sr_2Ca_3Cu_{(4-x)}Ag_xO_y (2234) Oxides Prepared by S.S.R. Method

Authors: SÜLEYMAN BOLAT, E. YANMAZ, H. CÖMERT

Abstract: The effect of Ag-doping Bi$_{1.6}$Pb$_{0.4}$Sr$_{2}$Ca$_{3}$Cu$_{4-x}$Ag$_{x}$O$_{y}$ compounds (x=0.0-1.0), prepared by conventional Solid-State-Reaction (SSR) technique, was studied using x-ray diffraction (XRD) and electrical resistivity. The high-T$_{c}$ fraction of the 2223 phase, formed from the nominal composition of 2234, decreases with increasing Ag content. From lattice parameter calculations it follows that Ag-doping the unit cell phase of (Bi,Pb)$_{2}$Sr$_{2}$Ca$_{2}$Cu$_{3}$O$_{y}$ is limited to the value of x$\leq$0.1. The zero resistance critical temperature (T$_{c,zero}$) was determined from the resistivity curves for all samples. The value of T$_{c,zero}$ decreases slightly to 106 K for x$\leq$0.4 and when the nominal silver content increases up to x=0.7 or more T$_{c,zero}$ strongly decreases to 72 K. The critical current density J$_c$ at 77 K decreases dramatically as silver content increases. This result is discussed on the basis of precipitation of low-T$_{c}$ 2212 and other impurity phases in Bi$_{1.6}$Pb$_{0.4}$Sr$_{2}$Ca$_{3}$Cu$_{4-x}$Ag$_{x}$O$_{y}$ compounds.

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