TY - JOUR A1 - Nassif, N. A1 - Pinna, N. A1 - Gehrke, N. A1 - Antonietti, M. A1 - Jäger, Christian A1 - Cölfen, H. T1 - Amorphous layer around aragonite platelets in nacre KW - Nacre KW - NMR KW - Aragonite KW - Amorphous Surface KW - Protein binding PY - 2005 SN - 0027-8424 SN - 1091-6490 VL - 102 IS - 36 SP - 12653 EP - 12655 PB - National Academy of Sciences CY - Washington, DC AN - OPUS4-11009 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bender, P. A1 - Fock, J. A1 - Hansen, M. F. A1 - Bogart, L. K. A1 - Southern, P. A1 - Ludwig, F. A1 - Wiekhorst, F. A1 - Szczerba, Wojciech A1 - Zeng, L. J. A1 - Heinke, D. A1 - Gehrke, N. A1 - Fernández Díaz, M. T. A1 - González-Alonso, D. A1 - Espeso, J. I. A1 - Rodríguez Fernández, J. A1 - Johansson, C. T1 - Influence of clustering on the magnetic N2 - Clustering of magnetic nanoparticles can drastically change their collective magnetic properties, which in turn may influence their performance in technological or biomedical applications. Here, we investigate a commercial colloidal dispersion (FeraSpinTMR), which contains dense clusters of iron oxide cores (mean size around 9 nm according to neutron diffraction) with varying cluster size (about 18–56 nm according to small angle x-ray diffraction), and its individual size fractions (FeraSpinTMXS, S, M, L, XL, XXL). The magnetic properties of the colloids were characterized by isothermal magnetization, as well as frequency-dependent optomagnetic and AC susceptibility measurements. From these measurements we derive the underlying moment and Relaxation frequency distributions, respectively. Analysis of the distributions shows that the clustering of the initially superparamagnetic cores leads to remanent magnetic moments within the large clusters. At frequencies below 105 rad s−1, the relaxation of the clusters is dominated by Brownian (rotation) relaxation. At higher frequencies, where Brownian relaxation is inhibited due to viscous friction, the clusters still show an appreciable magnetic relaxation due to internal moment relaxation within the clusters. As a result of the internal moment relaxation, the colloids with the large clusters (FSL, XL, XXL) excel in magnetic hyperthermia experiments. KW - Magnetic hyperthermia KW - Magnetic nanoparticles KW - Multi-core particles KW - Core-clusters PY - 2018 DO - https://doi.org/10.1088/1361-6528/aad67d VL - 29 IS - 42 SP - Articel 425705 PB - IOP Publishing CY - UK AN - OPUS4-47203 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heinke, D. A1 - Gehrke, N. A1 - Ludwig, F. A1 - Steinhoff, U. A1 - Pankhurst, Q. A. A1 - Lüdtke-Buzug, K. A1 - Thünemann, Andreas A1 - Johansson, Ch. T1 - NanoMag - Standardization of Analysis Methods for Magnetic Nanoparticles N2 - The NanoMag project brings together various leading experts in magnetic nanoparticle synthesis as well as nanoparticle analysis and characterization from research institutes, companies, universities and metrology institutes that will perform cutting-edge research and develop applications in the field of magnetic particles. This work is supported by the European Commission Framework Programme7 under the NanoMag project [grant agreement no 604448]. T2 - 2015 5th International Workshop on Magnetic Particle Imaging (IWMPI) CY - Istanbul, Turkey DA - 26.03.2015 KW - nanoparticles PY - 2015 UR - http://www.nanomag-project.eu/ SN - 978-1-4799-7269-2 SN - 978-1-4799-7271-5 DO - https://doi.org/10.1109/IWMPI.2015.7107065 VL - 2015 SP - P39 PB - IEEE AN - OPUS4-37324 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -