Secondary phases in (001) RBa2Cu3O(7-x) epitaxial thin filmsстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:The composition and orientation of secondary phases in epitaxial (001)RBa2Cu3O7-x thinfilms grown by MOCVD were investigated by HREM, XRD, SEM, and other techniques.The observed secondary phases often did not correspond to those expected from equilibriumphase diagrams of bulk R-Ba-Cu-O systems. No evidence was found for the presence ofR2BaCuO5 or BaCuO2, which are the equilibrium phases with bulk RBa2Cu3O7-x. In contrast,inclusions of well-oriented R2CuO4 (R ) Gd), R2O3 (R ) Lu, Ho, Y), R2Cu2O5 (R ) Lu), Ba2-CuO3, and BaCu3O4 were observed, depending on the films’ stoichiometry. It is concludedthat the formation of coherent or semicoherent interfaces between embedded inclusions andthe surrounding matrix is critical for a stabilization of otherwise nonequilibrium oxide phasesin epitaxial films. The crystal structure of unstable-in-bulk cuprate BaCu3O4 was determinedusing electron nanodiffraction of the films’ cross sections.