Structural and Superconducting Properties of Sr for Ba Substituted La1.5Nd0.5Ca1( Ba2-xSrx) Cu5Oz System

An attempt is made to investigate the effect of isovalent substitution (i. e. Sr+2 for Ba+2) and chemical pressure effect (i. e. smaller cation substitution) on the structure and superconductivity of La1.5Nd0.5Ca1(Ba2-xSrx) Cu5Oz, x = 0.0 -1.0, (LNCBSCO) system. A series of LNCBSCO system has been synthesized by a solid-state reaction route. All the compounds crystallize with the tetragonal LaBa2Cu3Oz type structure with the space group P4/mmm. The structural parameters of the prepared samples are obtained using X-ray diffraction (XRD) with Rietveld analysis. The electrical properties are also carefully investigated using the four-probe temperature dependent resistivity (R-T) technique. The oxygen content is estimated through Iodometric titration. All the samples show the well superconducting behavior with decreasing T-c values ranging from 79 K to 60 K for x = 0.0 to x = 0.8. Tc exhibits a strong correlation with doping concentration. We discuss possible reasons and inherent of the T-c(x) suppression.