Effect of size, composition, and morphology on magnetic performance: First-order reversal curves evaluation of iron oxide nanoparticles Available to Purchase

Superparamagnetic nanoparticles are employed in a broad range of applications that demand detailed magnetic characterization for superior performance, e.g., in drug delivery or cancer treatment. Magnetic hysteresis measurements provide information on saturation magnetization and coercive force for bulk material but can be equivocal for particles having a broad size distribution. Here, first-order reversal curves (FORCs) are used to evaluate the effective magnetic particle size and interaction between equally sized magnetic iron oxide (Fe₂O₃) nanoparticles with three different morphologies: (i) pure Fe₂O₃, (ii) Janus-like, and (iii) core/shell Fe₂O₃/SiO₂ synthesized using flame technology. By characterizing the distribution in coercive force and interaction field from the FORC diagrams, we find that the presence of SiO₂ in the core/shell structures significantly reduces the average coercive force in comparison to the Janus-like Fe₂O₃/SiO₂ and pure Fe₂O₃ particles. This is attributed to the reduction in the dipolar interaction between particles, which in turn reduces the effective magnetic particle size. Hence, FORC analysis allows for a finer distinction between equally sized Fe₂O₃ particles with similar magnetic hysteresis curves that can significantly influence the final nanoparticle performance.