Secondary phases in (001)RBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} epitaxial thin films

Journal Article · Wed Sep 01 00:00:00 EDT 1999 · Chemistry of Materials

DOI:https://doi.org/10.1021/cm991016v· OSTI ID:20001168

Samoylenkov, S V; Gorbenko, O Y; Graboy, I E; Kaul, A R; Zandbergen, H W; Connolly, E

The composition and orientation of secondary phases in epitaxial (001)RBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} thin films [where R is a rare earth element] grown by MOCVD were investigated by HREM, XRD, SEM, and other techniques. The observed secondary phases often did not correspond to those expected from equilibrium phase diagrams of bulk R--Ba--Cu--O systems. No evidence was found for the presence of R{sub 2}BaCuO{sub 5} or BaCuO{sub 2}, which are the equilibrium phases with bulk RBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. In contrast, inclusions of well-oriented R{sub 2}CuO{sub 4}(R = Gd), R{sub 2}O{sub 3} (R = Lu, Ho, Y), R{sub 2}Cu{sub 2}O{sub 5}(R = Lu), Ba{sub 2}CuO{sub 3}, and BaCu{sub 3}O{sub 4} were observed, depending on the films' stoichiometry. It is concluded that the formation of coherent or semicoherent interfaces between embedded inclusions and the surrounding matrix is critical for a stabilization of otherwise nonequilibrium oxide phases in epitaxial films. The crystal structure of unstable-in-bulk cuprate BaCu{sub 3}O{sub 4} was determined using electron nanodiffraction of the films' cross sections.

• Research Organization: Moscow State Univ. (RU)
• OSTI ID: 20001168
• Journal Information: Chemistry of Materials, Vol. 11, Issue 9; Other Information: PBD: Sep 1999; ISSN 0897-4756
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
RARE EARTH COMPOUNDS
BARIUM OXIDES
COPPER OXIDES
THIN FILMS
PHASE DIAGRAMS
CRYSTAL STRUCTURE