Polarized SANS as advanced characterization technique within the NanoMag project
Jeudi 7 avril 2016 14:00
- Duree : 1 heure 30 minutes
Lieu : ILL 4, Seminar Room (no 163), 71 avenue des Martyrs - Grenoble
Orateur : Philipp BENDER (Departmento CITIMAC, Faculty of Science, University of Cantabria, Santander, Spain)
In recent years, utilization of iron oxide nanoparticles for a wide range of biomedical applications was extensively researched [1], prompting the need to standardize the characterization of their physical properties. The aim of the EU FP7 project NanoMag (grant no. 604448) is to improve, redefine and ultimately standardize existing analysis methods [2]. For that purpose it is necessary to correlate the macroscopically measured quantities of the ensembles with the physical properties of the individual particles on the nanoscale. An open issue is yet to experimentally resolve the influence of local particle interactions within such ensembles on their magnetization behavior. A suitable technique to detect the intra- as well as inter-particle spin correlations due to dipolar interactions is Small Angle Neutron Scattering (SANS). To separately determine the magnetic cross correlation functions a longitudinal neutron spin analysis (POLARIS) can be utilized [3].
In this presentation, first results obtained within the NanoMag project are presented. Here the magnetization behavior of a dense powder of superparamagnetic iron oxide nanoparticles was characterized by POLARIS (instrument D33, ILL) as well as conventional magnetometry. Data analysis is performed by a model-independent Fourier transform of the POLARIS cross sections to extract the field dependent correlation functions [3]. A similar approach is used for the analysis of the magnetometry data (DC and AC) where the moment (DC) or relaxation time (AC) distribution is extracted by numeric inversion methods. The ultimate goal is to correlate the influence of dipolar interactions observed on the macro- and the nanoscale, as well as to evaluate if it’s feasible to establish numeric inversion techniques as the standard approach within the NanoMag project to analysis conventional magnetometry data of iron oxide nanoparticles (in analogy to Neutron/X-ray-Scattering).
Additionally, some selected results of other projects are presented where Neutron scattering or diffraction is/was used for the characterization of magnetic nanoparticles : BMBF project TISANE [3] (project number : 05K10TS1), NoCoBiNa project (project number : MAT2014-SS049-C2-R) [4].
1. www.nanomag-project.eu.
2. D. Honecker et al., Eur. Phys. J. B 76, 209-213 (2010).
3. P. Bender et al., Nanoscale 7, 17122-17130 (2015).
4. C. Echevarria-Bonet et al., Phys. Rev. B 87, 180407 (2013).
Contact : dubouloz@ill.fr
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