Preparation and properties of complex oxides in the Ca–Cu–In–Pb–Sr–Y–O system

Abstract

During the course of a search for new superconducting oxides two compositional ranges within the Ca–Cu–In–Pb–Sr–Y–O system have been explored. The compositions were (Ca_{1 –x}Y_x)Cu₂(In_{1 –x}Pb_y)Sr₂O_z and Cu(In_{1 –y}Pb_y)Sr₂O_z with the value of x varying from 0 to 0.9, the value of y varying from 0.5 to 0.7 and the oxygen stoichiometry dictated via the firing conditions.

Within these two compositional ranges only two crystalline phases, one tetragonal and one hexagonal, were found to be present in significant proportion. The tetragonal phase exhibited similar lattice symmetry and unit-cell dimensions to those of TlBa₂CaCu₂O₇ and the hexagonal phase exhibited lattice symmetry and unit-cell dimensions similar to those of Cu_0.66Pb_3.21Sr_4.79O_11.12. Both structures were obtained as single phases and each was shown able to accommodate a range of cation stoichiometry. None of the materials prepared in this work exhibited superconductivity.