Iron-based Nanoparticles and Their Mössbauer Spectra

Abstract

This review describes the synthesis of iron-based nanoparticles. Iron oxyhydroxide, iron oxide, iron carbide, and iron sulfide nanoparticles have been produced using various methods. Feroxyhyte δ-FeOOH nanoparticles were produced by the oxidation of precipitates obtained by hydrazine reduction of iron chloride. Similar nanocomposites doped with foreign atoms (Ag, Cu, or Zn) have been produced as well. Iron oxide (γ-Fe 2 O 3 ) nanoparticles have been produced by a polyol method. When a sulfide source was added into the solution during synthesis, iron sulfide nanoparticles were obtained. Using this technique, a metastable trivalent iron sulfide (Fe 2 S 3 ) was successfully synthesized. Amorphous iron/carbon particles were obtained by the sonochemical synthesis of ferrocene in diphenylmethane. Subsequent heating of the amorphous particles produced Fe 3 C, α-Fe, and γ-Fe nanoparticles. Laser ablation of iron metal in an organic solvent produced iron carbide nanoparticles. The reaction mechanism and the structures of the nanoparticles were studied using Mössbauer spectroscopy as well as X-ray diffraction and transmission electron microscopy.Key Words: iron-based nanoparticles, Mössbauer spectroscopy, polyol methods, sonochemistry, laser ablation in liquid doped with foreign atoms are intriguing because doi: 10.3769/radioisotopes.68.125 126 Vol. 68,No. 3 RADIOISOTOPES they are known to exhibit unique magnetic and optical properties. 10) A variety of methods have been employed to synthesize nanoparticles; e.g. the hydrazine reduction method, polyol method, sonochemical method, and laser ablation in a liquid. Our recent results, mainly based on Mössbauer spectroscopy, will be presented in the following sections. Iron oxide nanoparticles and their compositeswith foreign atoms 2 1 Feroxyhyte nanoparticles Feroxyhyte (δ-FeOOH), a very intriguing species of the iron oxide family, is the only ferric oxyhy-droxide that exhibits significant magnetization at room temperature. 11) Generally, feroxyhyte is not as abundant as other iron oxides/oxyhydroxides in nature, and hard to synthesize because of its instability.Feroxyhyte nanoparticles were found to be a promising photocatalyst for hydrogen production, 12) and the enhancement of the Fenton-like photocatalytic response of feroxyhyte nanoflake/carbon nanodot nanohybrids was reported. 13) Polyakov et al. synthesized anisotropic feroxyhyte nanoparticles in the presence of humic substances. 14)Recently, we synthesized extremely small spherical feroxyhyte nanoparticles stabilized with gela- Fig. 1 (a) X-ray diffraction pattern, (b) TEM image, (c) histogram of diameters and (d) HR-TEM image of the feroxyhyte nanoparticles.

Mössbauer spectroscopic investigations on iron oxides and modified nanostructures: A review

“…Mössbauer studies were carried out to a large extent and were well documented [ 11 , 29 , 62 ]. It is utilized effectively to determine the cationic distribution.…”

“…Iron oxide nanoparticles (IONPs) are widely used in various applications such as biomedicine, magnetic storage media, water treatment, electrochemical energy storage, and catalysis [ 7 – 10 ]. The large surface-to-volume ratio of IONPs which is a custom to surface energy plays an important role in maintaining stability, chemical compositions, and lattice constant [ 11 ]. The polymorph transition of IONPs is also an interesting aspects as it widens the scope of application by the same material with low cost and safe energy and time.…”

“…Superparamagnetic behaviour of IONPs which is strongly dependent on size of the IONPs is also one of the important aspects for magnetic nanoparticles [ 11 ]. They are introduced extensively in the field of magnetic resonance imaging (MRI), drug delivery, and hyperthermia [ 13 – 16 ].…”

Magnetic fraction of the atmospheric dust in Kraków – physicochemical characteristics and possible environmental impact

“…Such behaviour of the Mössbauer spectrum typically belongs to nanosized ferromagnetic or antiferromagnetic particles. Such grains/particles (of the sizes below a single domain boundary) will present reduced hyperfine fields owing to spin relaxation effects (Yamada and Nishida, 2019). Our Mössbauer spectroscopy results indicate that iron bearing particles in the aerosols are very small, showing a superparamagnetic behaviour at room temperature (RT) and becoming ferromagnetic while lowering the measurement temperature.…”

Magnetic fraction of the atmospheric dust in Kraków – physicochemical characteristics and possible environmental impact

“…Such behaviour of the Mössbauer spectrum typically belongs to nanosized ferromagnetic or antiferromagnetic particles. Such particles (of the sizes below a single domain boundary) will present reduced hyperfine fields owing to spin relaxation effects (Yamada and Nishida, 2019). Our Mössbauer spectroscopy results indicate that Fe-bearing particles in the aerosols are very small, showing a superparamagnetic behaviour at room temperature (RT) and becoming ferromagnetic while lowering the measurement temperature.…”