MICROSTRUCTURAL INVESTIGATION OF THE GROWTH OF YBA2CU3O7-X ND2CUO4/YBA2CU3O7-X TRILAYERED FILMS ON LASRGAO4 SUBSTRATES/

A HRTEM study of an YBCO/Nd2CuO4/YBCO trilayered films on LaSrGaO4 sub strate with PBCO as a template layer has shown that in-plane aligned a -axis oriented YBCO films may be grown on (100) LaSrGaO4 substrates by pulsed laser deposition, which contain some domains with the c-axis m isaligned by 90 degrees in plane of the films. A Nd2CuO4 insulating la yer, with a thickness of approximately 10 nm, may be grown epitaxially between a-axis oriented YBCO layers with its c-axis parallel to the c -axis of the YBCO layers. A 90 degrees-misoriented a-axis YBCO grain i n the lower YBCO layer can nucleate a 90 degrees-misoriented Nd2CuO4 g rain in the a-axis oriented Nd2CuO4 layer and this can further nucleat e a 90 degrees-misoriented YBCO grain in the top YBCO layer. Narrow ve rtical Nd2O3 plates were observed in 90 degrees-misoriented Nd2CuO4 gr ains formed epitaxially with the Nd2CuO4 grains. The interface between the PBCO templated layer and the LaSrGaO4 substrate is quite rough wi th some amorphous islands in the template layer.