Tunable Control of the Structural Features and Related Physical Properties of Mn_xFe_3–xO₄ Nanoparticles: Implication on Their Heating Performance by Magnetic Hyperthermia

Abstract

Four different manganese ferrite (Mn x Fe3–x O4) nanostructures (9 and 15 nm spheres (S1, S2), 18 nm nanoflowers (NFs), and 20 nm cubes (NC)) were prepared in this work through a thermal decomposition method by tuning the critical synthetic parameters. In all of the prepared materials, the cation composition of the ferrite phase was rather similar. The occurrence of a secondary phase of mangano-wüstite within Mn x Fe3–x O4 nanoparticles and its impact on the magnetic properties were studied in detail from static and dynamic magnetic measurements complemented with Mössbauer spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy (HRTEM) analysis, and X-ray photoelectron spectroscopy (XPS). All of the computed data were consistent with a deterioration of the magnetic output as the reduced phase becomes progressively important, leading to a marked spin disorder and the reduction of either the effective magnetic size or the saturation magnetization. The heating efficiency was measured from 100 up to 300 kHz and from 8 up to 24 kA/m, the NF sample being the one displaying the highest specific absorption rate (SAR) under all tested conditions. These results agreed with the physicochemical and magnetic characterization of the particles, highlighting the interest of the detailed characterization of the particles to understand their heating properties relevant for biomedical applications and others such as catalysis.

Cubic Mesocrystal Magnetic Iron Oxide Nanoparticle Formation by Oriented Aggregation of Cubes in Organic Media: A Rational Design to Enhance the Magnetic Hyperthermia Efficiency

“…It has been reported that the formation of magnetite by thermal decomposition in organic media is via the oxidation of wüstite, and it has been previously detected in relatively large magnetite NPs prepared under highly reductive environmental conditions, mainly with surfactants such as 1,2-hexadecanediol and solvents like OCT . Under these conditions, the oxidation rate is slower than the growth rate.…”

“…It has been reported that the formation of magnetite by thermal decomposition in organic media is via the oxidation of wustite, and it has been previously detected in relatively large magnetite NPs prepared under highly reductive environmental conditions, mainly with surfactants such as 1,2-hexadecanediol and solvents like OCT. 52 Under these conditions, the oxidation rate is slower than the growth rate. Then, depending on the cooling rate and the particle size, the total conversion of wustite and metal iron to magnetite may take place or a small fraction of these phases is preserved in the particle's inner core.…”

Facile Synthesis of Chromium-Doped Fe1.1Mn1.9O4 Nanoparticles and the Effect of Cr Content on Their Magnetic and Structural Properties

“…Furthermore, as can be seen from Figure 1b, the increase in Cr content leads to a shift in the position of (311) peak towards higher values of 2θ. The results of previous studies of cation-substituted spinel oxides [40,41] have shown that both of these results can be explained by the substitution of larger Mn ions (r Mn = 0.645 Å) by smaller Cr ions (r Cr = 0.615 Å) on the octahedral sites. Moreover, the shift in the (311) peak toward higher angles implies [42] that Cr was incorporated into the crystal lattice of Fe 1.1 Mn 1.9 O 4 .…”

Review on Medical Applications of Manganese Oxide (Mn2+, Mn3+, and Mn4+) Magnetic Nanoparticles

“…Singh et al [129] reported that the substitution of Mn 2+ ions in magnetite distinctly boosted the SAR value (SAR: 510 kW/kg). Hence, the efficiency of manganese-based hyperthermia agents relies on the concentration of Mn 2+ substitution, site of substitution, particle size, morphology, saturation magnetization, applied magnetic field, frequency, and the dosage of NPs [130]. Some of the manganese-based hyperthermia agents and their SAR values are represented in Table 2.…”