INDUCTION OF BIDIMENSIONALITY IN MIXED CU-TI PEROVSKITES

Control of structure and order in oxides is essential for the design o f new superconducting cuprates. The intergrowth of perovskite and rock salt layers, as found in bismuth, thallium and, very recently, the re cordbreaking mercury cuprates. is just one way to induce bidimensional ity. Defect ''all perovskite'' oxides, such as Ln(2)Ba(2)Cu(2)Ti(2)O(1 1) (Ln = La, Nd, Eu) are discussed as examples of a crystal-chemical a pproach to the induction of bidimensionality and order in mixed perovs kite oxides of copper.