Synthesis of monodisperse iron-platinum (FePt) nanoparticles by reduction of platinum acetylacetonate and decomposition of iron pentacarbonyl in the presence of oleic acid and oleyl amine stabilizers is reported. The FePt particle composition is readily controlled, and the size is tunable from 3- to 10-nanometer diameter with a standard deviation of less than 5%. These nanoparticles self-assemble into three-dimensional superlattices. Thermal annealing converts the internal particle structure from a chemically disordered face-centered cubic phase to the chemically ordered face-centered tetragonal phase and transforms the nanoparticle superlattices into ferromagnetic nanocrystal assemblies. These assemblies are chemically and mechanically robust and can support high-density magnetization reversal transitions.
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http://dx.doi.org/10.1126/science.287.5460.1989 | DOI Listing |
Struct Dyn
November 2024
Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden.
Light-matter interaction at the nanoscale in magnetic alloys and heterostructures is a topic of intense research in view of potential applications in high-density magnetic recording. While the element-specific dynamics of electron spins is directly accessible to resonant x-ray pulses with femtosecond time structure, the possible element-specific atomic motion remains largely unexplored. We use ultrafast electron diffraction (UED) to probe the temporal evolution of lattice Bragg peaks of FePt nanoparticles embedded in a carbon matrix following excitation by an optical femtosecond laser pulse.
View Article and Find Full Text PDFJ Control Release
December 2024
School of Pharmacy, Institute of Aging Medicine, Shandong Technology Innovation Center of Molecular Targeting and Intelligent Diagnosis and Treatment, Binzhou Medical University, Yantai 264003, PR China. Electronic address:
Radiotherapy (RT)-mediated immune activation is insufficient for effective therapy of triple-negative breast cancer (TNBC) due to the immunosuppressive tumor microenvironment. Herein, we developed an oxygen self-supplying nanoradiosensitizer to activate immunogenic cell death (ICD) and the cGAS-STING signaling pathway, elevating the anti-tumor immune response and improving radioimmunotherapy for TNBC. The nanoradiosensitizer was fabricated using astragaloside liposome-encapsulated FePt alloy and MnO nanocrystals (ALFM).
View Article and Find Full Text PDFNano Lett
November 2024
Department of Applied Biology and Chemical Technology and Research Institute for Smart Energy, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China.
The bit islands in magnetic patterns play a crucial role in advancing magnetic recording density, but the trade-off issues between miniaturization and scalable production are still challenging. Here we present a two-in-one technique of nanoimprint lithography (NIL)-assisted self-assembly using a specially engineered FePt-containing block copolymer (BCP), offering a simple one-step fabrication for L1-FePt bit-patterned media with high throughput. This method combines top-down NIL with bottom-up self-assembly to precisely control the ultrafine magnetic bits in the nanoscale patterns.
View Article and Find Full Text PDFACS Appl Mater Interfaces
October 2024
School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China.
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