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Small‐angle neutron and X‐ray scattering of dispersions of oleic‐acid‐coated magnetic iron particles
Author(s) -
Butter Karen,
Hoell Armin,
Wiedenmann Albrecht,
Petukhov Andrei V.,
Vroege GertJan
Publication year - 2004
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/s0021889804018564
Subject(s) - small angle x ray scattering , small angle neutron scattering , pulmonary surfactant , materials science , dispersion (optics) , scattering , particle (ecology) , oleic acid , particle size , neutron scattering , superparamagnetism , iron oxide , analytical chemistry (journal) , chemistry , crystallography , chemical engineering , magnetization , chromatography , optics , biochemistry , physics , oceanography , quantum mechanics , engineering , magnetic field , metallurgy , geology
This paper describes the characterization of dispersions of oleic‐acid‐coated magnetic iron particles by small‐angle neutron and X‐ray scattering (SANS and SAXS). Both oxidized and non‐oxidized dilute samples were studied by SANS at different contrasts. The non‐oxidized samples are found to consist of non‐interacting superparamagnetic single dipolar particles, with a lognormal distribution of iron cores, surrounded by a surfactant shell, which is partially penetrated by solvent. This model is supported by SAXS measurements on the same dispersion. Small iron particles are expected to oxidize upon exposure to air. SANS was used to study the effect of this oxidation, both on single particles, as well as on interparticle interactions. It is found that on exposure to air, a non‐magnetic oxide layer is formed around the iron cores, which causes an increase of particle size. In addition, particles are found to aggregate upon oxidation, presumably because the surfactant density on the particle surfaces is decreased.