Synthesis, characterization and magnetic properties of hollow Co₂FeAl nanoparticles: the effects of heating rate

Abstract

Magnetic hollow nanoparticles (HNPs) are of particular interest owing to their broad applications including targeted drug delivery and magnetic resonance imaging. Here, hollow Co2FeAl full-Heusler NPs were successfully synthesized using polyethylene glycol polymer as a capping agent, followed by thermal annealing at 700 °C with heating rates ranging between 5 and 15 °C/min. Increasing heating rate up to 15 °C/min decreased the mean particle size, as characterized by scanning and transmission electron microscopies (TEM). High resolution TEM images revealed the highly crystalline nature of the HNPs with different grain size. A maximum saturation magnetization of 95 emu/g and coercivity of 730 Oe were obtained using heating rates of 5 and 10 °C/min, respectively. Alternatively, first-order reversal curve (FORC) measurements at room temperature revealed the formation of a mixture of single-domain and superparamagnetic (SP) grains due to the presence of a wide range of particle size. With the increase in the heating rate, the SP contribution increased, which resulted in a decrease in the inter-particle magnetostatic interactions, thereby approaching the average coercivity obtained from hysteresis curve to FORC coercivity.

Size-dependent structural and magnetic properties of disordered Co2FeAl Heusler alloy nanoparticles

“…They found that the lattice constant of prepared nanowires was within 1% of the lattice parameter of the bulk system. Hollow CFA NPs were also prepared by using capping agent, namely polyethylene glycol polymer and then annealed at 700 °C with a heating range from 5 to 15 °C per min [26]. They achieved a maximum saturation magnetization of 95 emu/g and Hc of 730 Oe.…”

The influence of pH value and composition on the microstructure, magnetic properties of Co-Fe-Al Heusler nanoparticles

“…Sapkota et al synthesized Heusler alloy Co 2 FeAl nanowires by using electrospinning method with the existence of polymer [20]. Almasi-Kashi et al prepared Co 2 FeAl nanoparticles by using co-precipitation method with the existence of polymer [21,22]. Kumar et al prepared Co 2 FeAl nanoparticles by reducing a methanol impregnated mixture of metal salts [23].…”

Deciphering magnetic hyperthermia properties of compositionally and morphologically modulated FeNi nanoparticles using first-order reversal curve analysis

“…Considering the variation behavior of H C as a function of particle size (see figure 11.2 in [19]), decreasing the size of SD NPs is expected to reduce the corresponding H C. Thereby, the aforementioned trends measured in H C may be caused by the 43% decrease (from 112 to 64 nm) and 20% increase (from 64-77 nm) in the mean diameter of the SD FeNi NPs. Nevertheless, it should also be noted that an enhancement in the SP fraction of NPs can reduce the H C obtained from the hysteresis loop measurements [51]. Therefore, the SP fraction of the FeNi NP samples may differ from each other, which will be investigated in the next section using the FORC analysis.…”