Optical and Magnetic Properties of Fe Nanoparticles Fabricated by Femtosecond Laser Ablation in Organic and Inorganic Solvents

Abstract

Magnetic nanoparticles have attracted much interest due to their broad applications in biomedicine and pollutant remediation. In this work, the optical, magnetic, and structural characteristics of colloids produced by ultrashort pulsed laser ablation of a solid Fe target were studied in four different media: HPLC water, an aqueous solution of trisodium citrate, acetone, and ethanol. Optical extinction spectroscopy revealed an absorption band in the UV region for all, in contrast to the results obtained with nanosecond lasers. Micro-Raman spectroscopy showed that the samples are heterogeneous in their composition, with hematite, maghemite, and magnetite nanoparticles in all four solvents. Similar results were obtained by electron diffraction, which also found α-Fe. Magnetic properties were studied by vibrating-sample magnetometry, and showed nanoparticles in the superparamagnetic state. Under certain experimental conditions, submicrometer-sized iron oxide nanoparticles agglomerate into fractal patterns that show self-similar properties. Self-assembled annular structures on the nanometer scale were also observed and are reported for the first time.

Magnetic Fe@FeOx, Fe@C and α-Fe2O3 Single-Crystal Nanoblends Synthesized by Femtosecond Laser Ablation of Fe in Acetone

“…Their M s and H c values were measured to be 23, 80, 60, 67 and 14 emu/g, and 77, 92, 65, 56, and 52 Oe at 300 K, respectively. Santillán et al synthesized FeO x (Fe 3 O 4 , γ-Fe 2 O 3 or α-Fe) by fs laser (120 fs, 1 kHz, 800 nm) ablation of Fe in water, by which M s , number density, magnetic radius and total radius of 49.3 emu/g, 2.9 × 10 18 , 1.1 nm, 1.9 nm, respectively, were obtained, which were different from the magnetic properties (26.7 emu/g, 3468 μ B and 0.7 × 10 18 , 1.5 nm, 3.2 nm) of the particles obtained by LAL in a trisodium citrate aqueous solution [ 19 ]. Most of these works mainly focused on the hysteresis curves to reveal the dependence of magnetic properties on the phases of LAL-prepared FeO x or Fe/FeO x particles.…”

Highly fluorescent few atoms silver nanoclusters with strong photocatalytic activity synthesized by ultrashort light pulses

“…Pulsed laser ablation in liquids has emerged as an alternative technique for synthesize metal NPs since nanomaterials may be generated from almost any solid sample with high purity. Since laser ablation process produces ions and atoms in the plasma plume that reach different nucleation stages, large (radii > 20 nm), medium (2 nm < radii < 20 nm), small (1 nm < radii < 2 nm) and very small (radii < 1 nm) NPs are formed [21][22][23][24] .…”

Synthesis of Oxide Iron Nanoparticles Using Laser Ablation for Possible Hyperthermia Applications

“…Although Raman spectroscopy is a technique for studying atomic and molecular bonds in the chemistry and physics of condensed matter, care must be taken when applying it to the study of iron oxides. Magnetite bands are not shown as in the diffraction patterns and in the XPS spectra, which may be due to the phase change from magnetite to hematite because excessive exposure of an iron oxide sample to laser radiation has been shown to generate hematite, indicating that some peaks with Fe 2 O 3 phase could be attributed to this phenomenon [ 22 ]. The reported laser energy threshold values for hematite formation differ widely, depending on experimental conditions such as wavelength, exposure time, and sample surface characteristics.…”

“…In the literature, there are reports of magnetite nanoparticles produced by laser ablation, varying different parameters for obtaining them, as in the case of Santillán et al [ 22 ] who analyzed the characteristics of the iron oxide nanoparticles immersed in four different solutions, finding several phases of iron oxide and iron carbide. Svetlichnyi et al [ 23 ] and Ismail et al [ 24 ] synthesized iron oxide nanoparticles varying the media.…”