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Colloidal Interactions of Magnetic Nanoparticles
Published in Jeffrey N. Anker, O. Thompson Mefford, Biomedical Applications of Magnetic Particles, 2020
O. Thompson Mefford, Steven L. Saville
SANS is a rather new technique used to measure nanoparticle size and colloidal stability. As discussed above, with the correct scattering contrast, information can be gained regarding the structure or the organic stabilizing layer on the inorganic particle. For example Amstad et al. (2011) demonstrated the fitting of SANS data to determine the thickness of the stabilizing polymer on particles as well as interacting liposomes. Dennis et al. (2009) demonstrated the thickness of a dextran shell on magnetite nanoparticles via SANS. Changes in the solubility of the polymer brush due to thermal changes were observed for cobalt ferrite particles coated in poly(N-isopropylacrylamide) (pNIPAM) (Herrera et al. 2010).
Synthesis and Surface Functionalization of Ferrite Nanoparticles
Published in Jon Dobson, Carlos Rinaldi, Nanomagnetic Actuation in Biomedicine, 2018
Jennifer S. Andrew, Carlos Rinaldi, O. Thompson Mefford
Small angle neutron scattering (SANS) is a powerful technique for probing the organic stabilizing layer on the inorganic particle. Often, this is accomplished by contrast matching with the appropriate deuterated solvent to allow for better scattering of the material of interest. Several researchers have utilized this technique to determine the thickness of the stabilized polymer brush as a function of solvent or thermal environment.158–160 More recently, the spin structure of the magnetic particles have been investigated.154 This has included the use of a polarized source of neutrons that demonstrated spin canting on the surface of 9-nm magnetite nanoparticles in a 1.2 T field, where the thickness of this canted shell was dependent on temperature and applied field.161 Nonetheless, the major drawbacks to SANS is the need for experiments to be conducted near a steady source of neutrons. Typically, these are research reactors. In addition, the number of counts needed for each experiment can limit the observation of kinetic activities.
High-Performance Nanostructured Thermoelectric Materials Prepared by Melt Spinning and Spark Plasma Sintering
Published in D. M. Rowe, Materials, Preparation, and Characterization in Thermoelectrics, 2017
Xinfeng Tang, Wenjie Xie, Han Li, Baoli Du, Qingjie Zhang, Terry M. Tritt, Ctirad Uher
To supplement the microscopy study of the nanostructures, we have subsequently performed small angle neutron scattering (SANS) measurements. SANS is a well-established technique for characterizing nanostructures on length-scales from a few nm to a few hundreds nm, which greatly complements the electron microscopy study. In Figure 16.5 we present the SANS intensity (I) as a function of momentum transfer (Q) for the SE–MS–SPS and zone melted (ZM) samples. The plot is in a double-logarithmic scale. Due to the complexity of nanostructures, we shall restrict the data analysis to a comparison of the Q-dependence of scattered intensity in the two respective samples. First of all, the scattered intensity for the SE–MS–SPS sample exhibits a salient power-law behavior with an exponent, a = 3.7 between Qmin = 0.001 Å−1 and Qmax = 0.1 Å−1 that is, I ~ Q−a with a = 3.70 ± 0.01. This observation is consistent with the existence of a broad distribution of nanostructures over a decade or more in length-scale, which is consistent with the results concerning multiscale nanostructures in the electron microscopy study (Figures 16.3 and 16.4). In addition, the observed power-law exponent is close to a ≈ 4, which indicates that the interfaces among the nanostructures and the bulk matrix in the SE–MS sample are mostly homogeneous, or coherent, in accord with the HRTEM results.
The HighNESS Project at the European Spallation Source: Current Status and Future Perspectives
Published in Nuclear Science and Engineering, 2023
V. Santoro, K. H. Andersen, P. Bentley, M. Bernasconi, M. Bertelsen, Y. Beßler, A. Bianchi, T. Brys, D. Campi, A. Chambon, V. Czamler, D. D. Di Julio, E. Dian, K. Dunne, M. J. Ferreira, P. Fierlinger, U. Friman-Gayer, B. T. Folsom, A. Gaye, G. Gorini, C. Happe, M. Holl, Y. Kamyshkov, T. Kittelmann, E. B. Klinkby, R. Kolevatov, S. I. Laporte, B. Lauritzen, J. I. Marquez Damian, B. Meirose, F. Mezei, D. Milstead, G. Muhrer, V. Neshvizhevsky, B. Rataj, N. Rizzi, L. Rosta, S. Samothrakitis, H. Schober, J. R. Selknaes, S. Silverstein, M. Strobl, M. Strothmann, A. Takibayev, R. Wagner, P. Willendrup, S. Xu, S. C. Yiu, L. Zanini, O. Zimmer
The accuracy of Monte Carlo simulations, used for the design of moderator reflector systems, depends critically on the thermal neutron scattering libraries used as input to the simulations. Most of the thermal scattering libraries (TSL) in modern evaluations are created using the NJOY[6] code framework. A major limitation of this approach is that such libraries are limited both in the physics and the materials that are currently supported by NJOY, which is primarily aimed at reactor applications. Within the HighNESS project, several of the materials of interest facilitate neutron transport through specific processes, such as SANS and magnetic scattering, and require new developments to make it possible to perform design studies. Thus, the main aim of WP2 is the development of new software tools for the simulation of low-energy neutrons in the novel materials of interest for HighNESS. This includes magnesium hydride (MgH2), nanodiamond (ND) particles [in collaboration with WP6 (see Sec. VI)], clathrate hydrates, and intercalated graphite. The software is to be used by WP4 and WP6 for simulations of the advanced moderator reflector concepts. Experimental data collected in collaboration with WP3 are also used for benchmarking of the software. In addition, the main inputs to these software tools are being developed through detailed molecular modeling techniques.
Influence of intramolecular charge coupling on intermolecular interactions of polycarboxybetaines in aqueous solution and in polyelectrolyte multilayers
Published in Molecular Physics, 2021
Thomas Schimmel, Jörg Bohrisch, Dan F. Anghel, Julian Oberdisse, Regine von Klitzing
Aqueous solutions of polycarboxybetaines were prepared at concentrations from 0.1 down to 3.125 × 10 monomol/L obtained by successively dividing the concentration by two. They have been studied by small-angle neutron scattering (SANS). Figure 2 shows the reduced SANS intensities I(q)/Φ of the four samples at different concentrations, in DO at pH 2 adjusted by addition of HCl. All SANS samples have been prepared without added salt for reasons of colloidal stability. Due to the presence of HCl, and counterions introduced by each repeat unit, the Debye screening length is already rather low, typically 10 Å for 0.1 mol/L solutions, i.e. it corresponds to a high-ionic strength with considerable electrostatic screening.
Phase composition and magnetism of sol–gel synthesized Ga–Fe–O nanograins
Published in Phase Transitions, 2018
K. Rećko, J. Waliszewski, U. Klekotka, D. Soloviov, G. Ostapczuk, D. Satuła, M. Biernacka, M. Balasoiu, A. Basa, B. Kalska-Szostko, K. Szymański
This technique is often the only way to obtain information about the structure of the systems with chaotic or disordered distributions of scattering density inhomogeneities in the range of 8–1500 Å. The investigations of phase separation, size and extent of particle polydispersity are the SANS peculiarities. Making use of scattering techniques as neutron and X-rays is not common but if used, is based on the scattering vector dependence or exploits the full advantage relating the intensity to the volume of the scattering particle. SANS enables one to measure structural features by analyzing the scattering pattern at very low angles from the direct neutron beam. By examining the primary neutron beam, which are scattered at small angles, we can measure information that is directly proportional to the size and shape of nanometer-sized systems. A typical SANS graphics represents the scattering intensity as a function of the momentum transfer Q, where Q is defined asand depends on θ, the scattering angle, and λ, the neutron's wavelength of incident beam.