title: SAXS analysis of single- and multi-core iron oxide magnetic nanoparticles.
abstract: This article reports on the characterization of four superparamagnetic iron oxide nanoparticles stabilized with dimercaptosuccinic acid, which are suitable candidates for reference materials for magnetic properties. Particles p1and p2are single-core particles, while p3and p4are multi-core particles. Small-angle X-ray scattering analysis reveals a lognormal type of size distribution for the iron oxide cores of the particles. Their mean radii are 6.9 nm (p1), 10.6 nm (p2), 5.5 nm (p3) and 4.1 nm (p4), with narrow relative distribution widths of 0.08, 0.13, 0.08 and 0.12. The cores are arranged as a clustered network in the form of dense mass fractals with a fractal dimension of 2.9 in the multi-core particles p3and p4, but the cores are well separated from each other by a protecting organic shell. The radii of gyration of the mass fractals are 48 and 44 nm, and each network contains 117 and 186 primary particles, respectively. The radius distributions of the primary particle were confirmed with transmission electron microscopy. All particles contain purely maghemite, as shown by X-ray absorption fine structure spectroscopy.
authors.affiliation: Federal Institute for Materials Research and Testing (BAM), Unter den Eichen 87, 12205 Berlin, Germany; Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Aleja Mickiewicza 30, 30-059 Kraków, Poland.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Szczerba
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, ICMM/CSIC , Sor Juana Ines de la Cruz 3, 28049 Madrid, Spain.
authors.forename: Rocio
authors.initials: R
authors.lastname: Costo
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, ICMM/CSIC , Sor Juana Ines de la Cruz 3, 28049 Madrid, Spain.
authors.forename: Sabino
authors.identifier: https://orcid.org/0000-0002-3015-1470
authors.initials: S
authors.lastname: Veintemillas-Verdaguer
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, ICMM/CSIC , Sor Juana Ines de la Cruz 3, 28049 Madrid, Spain.
authors.forename: Maria Del Puerto
authors.initials: MD
authors.lastname: Morales
authors.affiliation: Federal Institute for Materials Research and Testing (BAM) , Unter den Eichen 87, 12205 Berlin, Germany.
authors.forename: Andreas F
authors.initials: AF
authors.lastname: Thünemann
keywords: SAXS; X-ray absorption fine structure; X-ray absorption near-edge structure; XANES; iron oxide; reference materials; small-angle X-ray scattering; superparamagnetic nanoparticles