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Small‐angle X‐ray scattering and X‐ray absorption near‐edge structure study of iron‐doped siloxane‐polyoxyethylene nanocomposites
Author(s) -
Chiavacci L.A,
Dahmouche K,
Santilli C.V,
De Zea Bermudez V,
Carlos L.D,
Briois V,
Craievich A.F
Publication year - 2003
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889803000517
Subject(s) - small angle x ray scattering , extended x ray absorption fine structure , xanes , absorption (acoustics) , siloxane , materials science , doping , x ray absorption fine structure , nanocomposite , scattering , absorption edge , crystallography , ion , analytical chemistry (journal) , chemistry , polymer , absorption spectroscopy , nanotechnology , spectral line , organic chemistry , spectroscopy , optics , composite material , physics , optoelectronics , quantum mechanics , astronomy , band gap
The local and medium‐range structures of siloxane‐POE hybrids doped with Fe(III) ions and prepared by the sol‐gel process were investigated by X‐ray absorption near‐edge structure (XANES)/extended X‐ray absorption fine structure (EXAFS) and small‐angle X‐ray scattering (SAXS), respectively. The experimental results show that the structure of these composites depends on the doping level. EXAFS data reveal that, for low doping levels ([O]/[Fe] > 40, oxygens being of the ether‐type of the POE chains), Fe(III) ions are surrounded essentially by a shell of chlorine atoms, suggesting the formation of FeCl 4 ‐ anions. At high doping levels ([O]/[Fe] < 20), Fe(III) ions interacts mainly with oxygen atoms and form FeO x species. The relative proportion of FeO x species increases with iron concentration, this result being consistent with the results of SAXS measurements showing that increasing iron doping induces the formation of iron‐rich nanodomains embedded in the polymer matrix.