OXY-ANION SUBSTITUTIONS IN THE SYSTEM [Y CE]2SR2-XBAXCU3O9-Y/

The partial substitution of oxy-anions for the Cu in the 'chain' sites in the system [Y/Ce]2Sr2-xBaxCu3O9-y has been examined, and the succe ssful substitution of borate, phosphate and sulphate groups at these s ites has been achieved. The highest substitution level (80% replacemen t of the 'chain' Cu sites) occurred for borate ions and was associated with a significant reduction in the unit-cell c-axis length. For phos phate and sulfate groups, however, the maximum substitution level corr esponded to only 25% of the 'chain' Cu sites. None of the samples prep ared showed any evidence for superconductivity.