Microstructural study of growth of a YBa₂Cu₃O_7−x/LaAlO₃/YBa₂Cu₃O_7−x trilayered film by pulsed laser deposition

Abstract

The growth process of a YBCO͞LaAlO 3 ͞YBCO trilayered film made by pulsed laser deposition has been studied by high resolution transmission electron microscopy (HRTEM). The high resolution images of the cross-section samples have shown that a 7 nm layer of LaAlO 3 has been grown epitaxially between c-axis oriented YBCO layers having the nominal thickness of 250 nm. A stacking fault in the LaAlO 3 layer may introduce a stacking fault into the YBCO layer, which may form nucleation sites for a-axis oriented grains. A second phase had been formed at the interface between the LaAlO 3 layer and the lower YBCO layer, which has been identified by image simulation and energy dispersive x-ray (EDX) analysis as a new tetragonal La-Al-Cu-O phase based on LaAlO 3 in which some of Al atoms have been replaced by Cu. The approximate lattice parameters of the new phase are a 0.38 nm and c 0.76 nm. However, no second phase was found at the interface between the lower YBCO layer and the LaAlO 3 substrate.

UTSI/CFFF MHD program completion and related activities

“…The vacuum techniques utilized to produce high quality buffer layer films include sputtering, [11][12][13] thermal and electron beam evaporation, 14-17 molecular beam deposition, 18,19 and pulsed laser deposition. 3,8,20,21 On the other hand, the non-vacuum techniques are sol gel processing, 22,23 metal-organic decomposition, 24-27 electrodeposition, 28,29 aerosol (spray) pyrolysis, 30, 31 electrophoresis, 32,33 and screen printing. 34 The vacuum-based methods have two shortcomings for long wire or tape production.…”