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Formation of structural defects and strain in electrodegraded Fe‐doped SrTiO 3 crystals due to oxygen vacancy migration
Author(s) -
Ascienzo David,
Kurt Onur,
Greenbaum Steve,
Bayer Thorsten J. M.,
Maier Russell A.,
Randall Clive A.,
Ren Yuhang
Publication year - 2018
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15407
Subject(s) - raman spectroscopy , materials science , vacancy defect , oxygen , doping , cathode , perovskite (structure) , analytical chemistry (journal) , chemical physics , crystallography , chemistry , optics , optoelectronics , physics , organic chemistry , chromatography
Abstract We report on our investigation of structural defect and strain formation in electrodegraded reduced and oxidized, Fe ‐doped SrTiO 3 (Fe: STO ) single crystals using optical second harmonic generation ( SHG ) and confocal Raman spectroscopy. SHG and Raman spectra reveal structural and electrochemical inhomogeneity resulting from the formation of Fe 4+ /oxygen ion and Fe 3+ /oxygen vacancy aggregation sites along the degraded anode and cathode interfaces, respectively. We show that mixed Fe 3+ /Fe 4+ states and structural strain gradients are generated across the color fronts. These results, as well as oxygen sublattice differences between the anodic and cathodic bulk, present the color front as an interface between two dominant oxygen bonding distortions. The strain near the color front shows a strong dependence on oxygen vacancy concentration and diffusion within the crystals. Our characterization of structural and electrochemical changes due to electric field‐induced strain and oxygen vacancy migration advances knowledge of electrodegradation in perovskite‐based titanate single crystals.