Phase Structure and Heating Efficiency of As-Synthesised Iron-Oxide Nanoparticles and after Long Time Storage in Glycerol

Abstract

In the present work the structural characteristics and heating efficiencies of iron-oxide nanoparticles were studied. The investigated samples were produced by co-precipitation of Fe-O nanoparticles from mixture of Fe 2+ and Fe 3+ salts in the alkaline environment. Furthermore, the influence of processing route and storage environment on the phase structure and heating efficiency was studies for glycol dispersed nanoparticles. The heating efficiency experiments were performed on 5 wt% glycerol dispersions of Fe-O nanoparticles. The measurements were carried out on specimens directly after precipitation and for those kept in glycerol for substantial period of time in order to determine how the storage environment can impact their performance as a heating medium. Furthermore, comparative studies for nanoparticles produced at different processing routes were performed. The structural studies were carried out using X-ray diffractometry and transmission electron microscopy. The heating efficiencies and specific loss powers were determined using the self-constructed setup operating in the alternating magnetic field of various amplitudes from 2 to 4 kA/m and frequency of 100 kHz.

Fe3O4 Magnetic Nanoparticles Obtained by the Novel Aerosol-Based Technique for Theranostic Applications

“…However, due to the low saturation magnetization of these samples, their dispersions subjected to high-frequency external magnetic fields have shown a rather weak T(t) response. It was found that SLP and ILP values were relatively low compared to those measured for magnetite NPs co-precipitated using standard procedures [9,38,39,53].…”

“…Furthermore, the effect of a slightly higher d b than d t for dispersions used for measurements should not be neglected. Much lower SLP values for studied AeroNPs compared to SLP measured for dispersion of bare co-precipitated Fe 3 O 4 nanoparticles [38,39] and these coated with TEA-oleate [9] might be related to the smaller sizes of the 2AeroNPs-top and 2AeroNPs-bottom and their smaller agglomerates formed before coating them with TEA-oleate. The possible factor that might influence the differences in obtained SLP is the impact of TEA-oleate coating on the magnetic properties of the nanoparticles.…”

“…As shown in Figure 10, the TEA-oleate coating caused a significant reduction of the magnetic moment (M) of NPs. Furthermore, SLP measurements reported in [9,38,39] were performed for NPs dispersed in glycerol, which can alter the relaxation mechanism in NPs subjected to high-frequency external magnetic fields. The ILP(f ) dependencies were of the same order of magnitude for both H = 5 kA/m and H = 15 kA/m.…”

“…An efficient and low-cost method used for the synthesis of Fe 3 O 4 NPs is co-precipitation [38,39]. This involves dropwise addition of the basic solution into the solution of salts containing Fe 2+ and Fe 3+ ions.…”