Structural and electrical properties of cerium doped Bi(Pb)-2212 phases
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In this work, a comparative study on the effect of doping by low content cerium at Ca site of Bi(Pb)-2212 phases is presented. Superconducting ceramics of nominal compositions Bi2Sr2Ca1-xCexCu2O8+delta (called CC series) and Bi1.6Pb0.4Sr2Ca1-xCexCu2O8 + delta (called PCC series) with x=0, 0.025, 0.05, 0.075 and 0.1 are successfully synthesized in air by conventional solid state reaction. They are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and resistivity measurements. In both series, the doping reduces the cell volume of samples. SEM photographs show that the samples are composed of grains with a flat shape that characterizes Bi-based cuprates. Quantitative EDS analysis confirms the reduction of Ca content and the increase of Ce one. The variation of resistivity with temperature shows that all samples exhibit a metallic-like character in the normal state. For all doping levels, the PCC series present highest onset critical transition temperatures. The highest value of 90.84 K is obtained for x=0.075 of Ce content, a result which is in line with that obtained in Y doped series. Also, samples of PCC series are more homogeneous. The residual resistivity increases with cerium content in both series, suggesting that doping introduces structural defects and disorder into the samples. (c) 2014 Elsevier By. All rights reserved.