Synchrotron X-Ray Absorption Spectroscopy Study of Self-Assembled Nanoparticles Synthesized from Fe(acac)₃and Pt(acac)₂

Abstract

The synchrotron X-ray absorption technique was used to complement electron microscopy in the investigation of nanoparticles synthesized from the coreduction of iron acetylacetonate, Fe(acac)3and platinum acetylacetonate, Pt(acac)2. A much higher Pt composition than Fe leads to an extended X-ray absorption fine structure (EXAFS) spectrum for the sample that differs from that of fcc FePt nanoparticles. Most importantly, X-ray absorption near-edge structure (XANES) spectra clearly indicate the existence ofα-Fe2O3and Pt metal. Since these monodisperse nanoparticles have a diameter of around 4 nm and tend to self-assemble into hexagonal arrangements, they can be modeled as Pt-rich cores with anα-Fe2O3shell stabilized by organic surfactants.

Investigation of Surfactant Effect on Size Distribution of FePt-based Nanoparticles by Synchrotron SAXS and TEM

“…The increase in oleic acid and oleylamine from 0.5 to 3.5 mmol, while the constant ratio of Fe to Pt sources, tend to balance the Fe and Pt compositions. A ratio of Fe to Pt sources of 2:1 was used in samples 1-4 because the Fe:Pt ratios in nanoparticles in previous study [15] were much less than unity. Based on the excessive fraction of Fe Table 1, the ratio of Fe to Pt sources was then reduced to 3:2 in the synthesis of samples A and B.…”

“…After cooling down to room temperature under nitrogen blanket, the surface-modified particles were isolated, purified and suspended by a procedure described in our previous work [15]. The magnetic colloids were dropped on carbon coated copper grids and hexane was allowed to evaporate at room temperature overnight.…”

Magnetic field-directed self-assembly of FePt-based nanoparticles at the liquid–air interface

“…The nanoparticles were surface-modified with oleic acid and oleylamine, and then dispersed in hexane. Their synthesis and properties are detailed in [14]. In the self-assembly at the liquid-air interface, a 0.3 mg/mL nanoparticle suspension was dropped on the surface of diethylene glycol (DEG) in a glass cylinder (2 cm diameter, 1.5 cm height).…”

Application of Image Processing to Determine Size Distribution of Magnetic Nanoparticles

“…Magnetic nanoparticles were synthesized from Fe(acac) 3 and Pt(acac) 2 in the polyol process which detailed in the previous work [13]. These nanoparticles were surfacemodified by oleic acid/oleylamine and dispersed without sedimentation in n-hexane.…”