Research Information System
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 2025 (SCI-Expanded)
Superparamagnetic iron oxide nanoparticles are widely used for magnetic hyperthermia, yet their modest saturation magnetization limits heating efficiency. Here, a simple route to graphitic carbon-coated iron-cobalt (FeCo) nanocrystals that retain near-bulk saturation magnetization and deliver competitive heating is reported. Single-phase FeCo ingots are arc-melted, crushed, mechanically milled with graphite for 5 h under argon and annealed at 400-800 degrees C in forming gas to form protective graphitic shells. X-ray diffraction and transmission electron microscopy confirm body-centered cubic FeCo cores encapsulated by a continuous carbon shell. After annealing at 400 degrees C, the sample achieves a saturation magnetization of 240 emu g-1 and a specific absorption rate (SAR, a measure of heating efficiency) of 191.5 W g-1 at 300 kHz and 325 Oe. Higher annealing temperatures increase graphitization and coarsening and reduce both saturation magnetization and SAR. Optimum performance at 400 degrees C is attributed to oxidation-limiting shells of near-optimal thickness. These results identify graphitic carbon-coated FeCo nanocrystals as a promising platform for magnetic hyperthermia. Although ethanol is nonphysiological, it was used to benchmark intrinsic heating capacity; biocompatibility and colloidal stability in aqueous media will be addressed in future work.