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Unusual Strain Accommodation and Conductivity Enhancement by Structure Modulation Variations in Sr 4 Fe 6 O 12+ δ Epitaxial Films
Author(s) -
Solís Cecilia,
Rossell Marta D.,
Garcia Gemma,
Van Tendeloo Gustaaf,
Santiso José
Publication year - 2008
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200701011
Subject(s) - materials science , pulsed laser deposition , epitaxy , perovskite (structure) , oxide , oxygen , thin film , substrate (aquarium) , conductivity , oxygen permeability , electrical resistivity and conductivity , microstructure , ionic bonding , chemical engineering , analytical chemistry (journal) , nanotechnology , ion , composite material , layer (electronics) , metallurgy , chemistry , oceanography , engineering , quantum mechanics , physics , organic chemistry , electrical engineering , geology , chromatography
Mixed ionic and electronic conducting (MIEC) films can be applied in solid state electrochemical devices such as oxygen separation membranes for producing pure oxygen, gas sensors or as cathode in solid oxide fuel cells. The current interest in layered perovskite‐related phases, like Sr 4 Fe 6 O 13 (SFO), arises from their significant oxygen permeability as predicted from theoretical studies. Nevertheless, before any practical application further fundamental study on this fairly unknown oxide is required mainly to assess the mechanisms affecting the transport properties. Epitaxial Sr 4 Fe 6 O 12+ δ (SFO) films of b ‐axis orientation with different thicknesses have been prepared by the pulsed laser deposition technique onto different perovskite substrates: SrTiO 3 , NdGaO 3 and LaAlO 3 . The strain accommodation has been found to vary as a function of film thickness as well as the substrate material causing different type of defects in the film microstructure, as well as variations in the oxygen anion content and ordering. Correspondingly, the total electrical conductivity of the films has been also found to vary significantly as a function of thickness and substrate type showing an unexpected enhancement for strained thin films. The variations in the transport properties are discussed in terms of the different strain accommodation mechanisms and the variation of the modulated structure observed for this compound.