Synthesis of monosized magnetic-optical AuFe alloy nanoparticles

Abstract

We report the preparation and characterization of multifunctional AuFe alloy nanoparticles of three compositions, Au0.25Fe0.75, Au0.5Fe0.5, and Au0.75Fe0.25, by a polyol process. It is found that the fusion of the two elements into one nanostructure entity retains the optical and magnetic properties of the individual components. The x-ray diffraction and transmission electron microscopy analyses confirm the formation of the alloy nanostructure with a narrow distribution of particle sizes and provides the detailed structural arrangements. The magnetic investigation shows the superparamagnetic or soft ferromagnetic behavior of the nanoparticles at room temperature, whereas the UV-visible measurements display the variation of the absorption bands at ∼560nm. The AuFe nanoparticles are rendered water soluble after thiolation.

Facile growth of monocrystalline gold–iron nanocrystals by polymer nanoemulsion

“…In this work, we report the one-pot nanoemulsion synthesis of long-term stable, monodisperse AuFe optical-magnetic nanocrystals employing the polymer. The resulting AuFe nanocrystals show high monocrystallinity, in sharp contrast to the polycrystalline state of the similar nanoparticles obtained previously [11,12]. In our experiments, the polymer dominantly plays the role of a surfactant, whereas the functioning of reduction is taken by the much stronger reductant of 1,2-hexadecanediol [15,20].…”

“…Ascribing to its marvelous magnetic properties and readiness to be converted to bio-friendly oxides, the element iron is an excellent candidate for a wide range of applications such as magnetic recording, magnetic seals, printing, magnetic resonance imaging, drug delivery, biodetection, and cell tagging and separation [7][8][9][10]. Appreciably, amalgamation of Au and Fe into one AuFe alloy or intermetallic nanostructure can be more fascinating than the corresponding monoelements, offering potential functions in both magnetic and optical properties in addition to the biological compatibility and easy linkage to biomolecules endowed by the constituents [1,2,[11][12][13]. In such nanostructures, particle size and distribution, shape, composition, crystallinity, microstructure, surface properties, and aqueous solubility are vital.…”

“…In such nanostructures, particle size and distribution, shape, composition, crystallinity, microstructure, surface properties, and aqueous solubility are vital. Facile synthesis, fine tuning of the surface properties, and precise control of the particle size and distribution are the intensive efforts of current research programs [1,[11][12][13].…”

Superparamagnetic Nanoparticles as High Efficiency Magnetic Resonance Imaging T2 Contrast Agent

“…14 −16,31,40 The corresponding peaks of iron and gold, reported in Figure 1e and Figure 1f, are analyzed and are in good agreement with reported values. [14][15][16]31,40 The lattice parameters of bulk Au/Fe alloys have been characterized in a wide range of compositions, for example, 3.3% Fe (4.0690 Å) and 20% Fe (3.995 Å). 41 Application of Vegard's law in this range allows for an estimation of the iron composition from the lattice parameter, which results in 10.3% Fe for MPSA:OT Au/ Fe NPs and 12.3% Fe for MUS:OT Au/Fe NPs.…”

“…A number of different methods have been previously reported for the preparation of bimetallic Au/Fe alloy nanoparticles, 13−15,20−26 core−shell or dumbbell nanoparticles, 27,28 with protocols including thermal decomposition, 15,23 pulsed laser deposition, 29,30 microemulsion techniques, 16,31 thermal vaporization, 32,33 laser-assisted synthesis in solution, 13,20 and aqueous reduction by borohydride derivates. 14 Chemical reduction of metal ions by sodium borohydrides has previously been used to prepare nanocrystalline magnetic materials, nanoalloys, and amorphous metals.…”