Microstructure of epitaxial YBa2Cu3O7-δ thin films grown on Pb(Mg1/3Nb2/3)0.7Ti0.3O3 substrates

The microstructure of epitaxial c-axis oriented YBa2Cu3O7-delta (YBCO) thin films grown on piezoelectric/ ferroelectric (001) Pb(Mg1/3Nb2/3)(0.7)Ti0.3O3 (PMN-PT) substrates by pulsed laser deposition has been studied using transmission electron microscopy. It is shown that major defects in the films are interfacial misfit dislocations and planar defects. Moreover, a small amount of a-axis oriented domains with inclined domain walls are observed in the YBCO films and the formation mechanism of the inclined domain walls is discussed. In addition, tiny precipitates near the interface are observed in some cases. All these defects and the domain structure contribute to the strain relaxation of the epitaxial YBCO thin films. These findings may be helpful for future research on correlation of microstructure and physical properties in the high-T-c superconductor-ferroelectric heterostructures. (C) 2012 Elsevier B.V. All rights reserved.