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Insights on Growth and Nanoscopic Investigation of Uncommon Iron Oxide Polymorphs
Author(s) -
Carraro Giorgio,
Maccato Chiara,
Bontempi Elza,
Gasparotto Alberto,
Lebedev Oleg I.,
Turner Stuart,
Depero Laura E.,
Van Tendeloo Gustaaf,
Barreca Davide
Publication year - 2013
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201300873
Subject(s) - x ray photoelectron spectroscopy , nanorod , high resolution transmission electron microscopy , scanning transmission electron microscopy , nanomaterials , transmission electron microscopy , chemistry , nanotechnology , energy dispersive x ray spectroscopy , spectroscopy , scanning electron microscope , electron energy loss spectroscopy , dark field microscopy , analytical chemistry (journal) , oxide , crystallography , chemical engineering , materials science , microscopy , optics , physics , engineering , composite material , organic chemistry , chromatography , quantum mechanics
Si(100)‐supported Fe 2 O 3 nanomaterials were developed by a chemical vapor deposition (CVD) approach. The syntheses, which were performed at temperatures between 400 and 550 °C, selectively yielded the scarcely studied β‐ and ϵ‐Fe 2 O 3 polymorphs under O 2 or O 2 + H 2 O reaction environments, respectively. Correspondingly, the observed morphology underwent a progressive evolution from interconnected nanopyramids to vertically aligned nanorods. The present study aims to provide novel insights into Fe 2 O 3 nano‐organization by a systematic investigation of the system structure/morphology and of their interrelations with growth conditions. In particular, for the first time, the β‐ and ϵ‐Fe 2 O 3 preparation process has been accompanied by a thorough multitechnique investigation, which, beyond X‐ray photoelectron spectroscopy (XPS) and field‐emission scanning electron microscopy (FESEM), is carried out by X‐ray diffraction (XRD), energy‐dispersive X‐ray spectroscopy (EDXS), atomic force microscopy (AFM), high‐resolution transmission electron microscopy (HRTEM), electron diffraction (ED), scanning TEM electron energy‐loss spectroscopy (STEM‐EELS), and high‐angle annular dark‐field STEM (HAADF‐STEM). Remarkably, the target materials showed a high structural and compositional homogeneity throughout the whole thickness of the nanodeposit. In particular, spatially resolved EELS chemical maps through the spectrum imaging (SI) technique enabled us to gain important information on the local Fe coordination, which is of crucial importance in determining the system reactivity. The described preparation method is in fact a powerful tool to simultaneously tailor phase composition and morphology of iron(III) oxide nanomaterials, the potential applications of which include photocatalysis, magnetic devices, gas sensors, and anodes for Li‐ion batteries.