MICROSTRUCTURE OF A-AXIS ORIENTED YBCO FILMS ON SRTIO3 SUBSTRATES USING A NEW TEMPLATE LAYER LA4BACU5O13

a-axis oriented YBa2Cu3O7-delta (YBCO) films on La4-xBaxCu5O13-delta ( LBCO) template layers and multilayer structures with La4-xBaxCu5O13-de lta as intermediate layer have been characterized by X-ray diffraction and high resolution electron microscopy. La4-xBaxCu5O13-delta as temp late layer induces a-axis growth of YBa2Cu3O7-delta films with T-c(R = 0)= 81 K although the presence of c-axis domains at the interface is not entirely suppressed. Depending on the deposition temperature, this material can take the form of a disordered perovskite or exhibits a l ocal ordering between the La and Ba cations of the type A(4)B. Moreove r La4-xBaxCu5O13-delta can be used as intermediate layer for SNS-type structures permitting the growth of a second YBCO layer in a-axis orie ntation. (C) 1997 Elsevier Science B.V.