Structural aspects of superconducting cuprates

Salient structural features of the important families of cuprate superconductors are briefly reviewed. Correlations between the superconducting transition temperature and some of the crucial structure parameters are discussed. Correlations include those with the in-plane Cu-O distances, apical Cu-O distance, Madelung potentials and bond valence sums. The transformation of $YBa_2Cu_3O_{6.7}$ (123 cuprate) to a $YBa_2Cu_4O_8$ (124)-type phase is examined. Structural features of the newly discovered oxyanion derivatives of cuprates are pointed out