Publication Type:Journal Article
Source:Physica C: Superconductivity and its applications, Volume 170, Number 3-4, p.325-332 (1990)
Keywords:AC Susceptibility, Ceramic materials, heterostructures, High temperature superconductors, Microscopic Examination–Transmission Electron Microscopy, Oxide superconductors, Praseodymium Barium Copper Oxides, Praseodymium Compounds, Yttrium barium copper oxides, yttrium compounds
We have studied the microstructure of epitaxial a,b-axis oriented YBCO-PrBCO heterostructures using transmission electron microscopy. These films, grown on single crystal  SrTiO3 or LaAlO3 by pulsed laser deposition, have a Tc,0 of 84 K as determined by DC resistivity and AC susceptibility measurements. The PrBCO layer acts as a good buffer and template layer for the subsequent growth of a-axis oriented YBCO layer. Planar sections reveal the existence of two 90° rotated variants, with a small (<5%) fraction of c-axis oriented regions. These films are relatively free of polytypoidic defects, compared to c-axis oriented films. Selected area electron diffraction patterns obtained from cross sections and planar sections reveal the orientation relationship in which the a-axis of the YBCO layer and the b-axis of the PrBCO layer are normal to the substrate surface. © 1990.
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