Effects of Ba doping on Tc and vibration features of (Pb, Cd)-1212 cuprates

Abstract Samples of nominal composition (Pb 0.5 Cd 0.5 ) (Sr 2− x Ba x ) (Ca 0.5 Y 0.5 )Cu 2 O y (0⩽ x ⩽0.5) synthesised at 920°C in air are investigated. XRD shows the samples to exhibit the tetragonal 1212-phase. The lattice parameters, the width of the Raman peak for the apical-0(2) vibration mode and the infrared absorption peak for the 0(3) vibration mode, all increase with increasing Ba doping level. In the doping range (0.0⩽ x ⩽0.5), there is a transition from insulator to superconductor. The Raman shift and the wavenumber of the infrared absorption for the phonon peaks appear to change regularly.