Decomposition Of Iron Oleate Complex Research Articles

Growth of Fe3O4 nanoparticles with tunable sizes and morphologies using organic amine

Fe3O4 nanoparticles (NPs) have been synthesized by the thermal decomposition of iron oleate complex in 1-octadecene solutions using organic amines as stabilizers such as trioctylamine (TOA), oleylamine (OAm), and hexadecylamine (HDA). By optimizing preparation conditions such as temperature, time, and the concentration of reaction reagents, the NPs exhibited adjusted sizes and morphologies (spherical, truncated octahedral, cubic, and tetrahedral). Organic amines play an important role for the morphology of the NPs. For example, truncated octahedral shape was gradually changed into quasi-cubic shape if adding TOA in the reaction system for a long time. In contrast, spherical, cubic, and tetrahedral Fe3O4 NPs were fabricated in the case of OAm used. Because of OAm used as a reducing agent, reaction temperature was decreased. HDA resulted in spherical Fe3O4 NPs a large size. It is confirmed that organic amine molecules were bound on the surface of the NPs by measuring the Fourier transformation infrared spectroscopy of samples.

Synthesis and Characterization of Oleic Acid Stabilized Monodisperse Magnetite Nanocrystals for Magnetic Resonance Imaging Applications

Oleic acid stabilized magnetite nanocrystals have been synthesized by the organic phase thermal decomposition of iron oleate complex in 1-octadecene for potential application as magnetic resonance imaging (MRI) contrast agent. The synthetic process resulted in 13.5 and 15.1 nm highly monodisperse nanocrystals as revealed by transmission electron microscopy. Proton nuclear magnetic resonance ( 1 HNMR) spectroscopy and Fourier-transformed infrared spectroscopy results confirm that the nanocrystals are free from 1-octadecene, and that the oleic acid is chemisorbed on the nanocrystals which are critical for their safety and long term stability, respectively. X-ray powder diffractometry of the nanocrystals strongly suggest magnetite nanocrystalline phase. The magnetic properties of the nanocrystals were examined by superconducting quantum interference device magnetometer. The results indicate the superparamagnetic properties of the nanocrystals at room temperature and their large saturation magnetizations. 1 H-NMR relaxometry measurements demonstrate large longitudinal (r 1 ) and transverse (r 2 ) relaxivities of 32.6 and 96.3 mM -1 s -1 , respectively for 15.1 nm nanocrystals with r 2 /r 1 relaxivity ratio of ~ 3.0 at 37 oC demonstrating their potential as promising MRI contrast agents. Keywords : magnetite, nanocrystals, superparamagnetic, relaxometry, magnetic resonance imaging

Synthesis and magnetic properties of octahedral magnetite nanoparticles in 20–110 nm range

Octahedral magnetite (Fe3O4) nanoparticles (NPs) with dimensions ranging from 20 to 110 nm are prepared via the decomposition of iron oleate complex in the presence of cetyltrimethylammonium bromide (CTAB) and various organic solvents. It is shown that the addition of an optimal amount of CTAB prompts the growth of equi-dimensional octahedral NPs with dominant {111} facets. Moreover, it is shown that the size of the octahedral NPs can be controlled by adjusting the relative amounts of oleic acid and CTAB and choosing an appropriate high-boiling point organic solvent. The X-ray diffraction analysis results reveal that the compositions of the as-synthesized NPs are solvent-dependent and contain different amounts of iron metal, wustite and magnetite phases. The as-synthesized NPs are oxidized to pure magnetite via an air treatment and the room-temperature magnetic properties of the resulting products are then characterized by means of a superconducting quantum interference device. The results indicate that the superparamagnetic limit for the current magnetite NPs is equal to approximately 33.3 nm at a temperature of 300 K.

Synthesis of Fe3O4 Nanoparticles with Tunable and Uniform Size Through Simple Thermal Decomposition

A novel and facile method with low cost has been developed to fabricate Fe3O4 nanoparticles (NPs) with tunable and uniform sizes by the thermal decomposition of iron oleate complex. The synthesis of iron oleate complex was carried out using a reaction between oleic acid and FeCl3 x 6H2O at low temperature. The decomposition of iron oleate complex occurs when the complex added in the solution of octadecene (ODE) and trioctylamine (TOA) with simple heat treatment. The X-ray diffraction pattern of a resulting sample indicated that Fe3O4 NPs formed during the decomposition of iron oleate complex. Preparation conditions including reaction time and temperature, the concentration of the complex, and the ratio of TOA and ODE strikingly affected the size and size distribution of resulting Fe3O4 NPs. Under optimal preparation conditions, the size of Fe3O4 NPs was adjusted (less than 20 nm in average diameter). The analysis of samples by a Fourier transform infrared spectroscopy confirmed the formation of iron oleate complex. Because the Fe3O4 NPs revealed a superparamagnetic property as well as tunable and uniform sizes, the NPs will be utilizable for further applications. This simple strategy with low cost has to give a useful enlightenment for the design and fabrication of magnetic oxide.

Size and Shape Controllable Synthesis of Monodisperse Iron Oxide Nanoparticles by Thermal Decomposition of Iron Oleate Complex

We have demonstrated the effects of reaction temperature, reaction concentration, surfactant concentration, refluxing time, seed-mediated growth, and heating rate on the size and morphology of iron oxide nanoparticles synthesized by thermal decomposition of iron oleate complex through “heating-up” process. By precisely controlling the reaction parameters, monodisperse iron oxide nanoparticles with the sizes ranging from 7 to 35 nm and controllable shapes are obtained. The formation kinetics of monodisperse iron oxide nanoparticles is experimentally studied and discussed. The results can be helpful in generally understanding the mechanism of thermal decomposition method.

Synthesis of Ferrite Nanoparticle and Ferrite-Gold Heterostructures

The synthesis of uniform and monodispersed magnetic and optical nanocrystals has received much attention in recent years due to the size-dependent physicochemical properties. In this study, we have demonstrated a general approach for the synthesis of size-tunable ferrite and gold nanocrystals and their nanocomposite. The monodispersed magnetite nanocrystals were obtained by thermal decomposition of iron-oleate complex in a high boiling point solvent in presence of oleylamine and oleic acid. The size of magnetite nanocrystal can be tuned from 7 – 11nm by changing the amount of iron-oleate complex. The other key parameters such as temperature, amount of capping agents, types of solvent were also discussed. This synthetic procedure could also apply to synthesis other type of ferrite nanocrystals. When Mn-acetate was partially substituted for iron-oleate in a 1:2 ratio in the same reaction conditions as in the synthesis of Fe3O4, monodispersed MnFe2O4 nanocrytals with 14nm could be obtained. Except those magnetic nanocrystals, we also synthesized various sizes of monodispersed gold nanocrystals by reducing HAuCl4 in presence of t-butylamine-borane and oleylamine. By varying the reaction temperature, the particle size could be well-tuned from 2nm to 8nm with the characteristic surface plasmon absorption between 510 and 520 nm. For Fe3O4/Au composite, it was prepared via the decomposition of iron-oleate over the surface of the Au nanoparticles. The mean size of the Fe3O4/Au nanocomposite was ∼17 nm which shows a saturation magnetization of 46.92 emu/g and absorption peak at 512nm. These composites with both magnetic and optical properties would make them very promising in the fields of biomedine and environment.

Size control and characterization of wustite (core)/spinel (shell) nanocubes obtained by decomposition of iron oleate complex

Monodisperse wustite (core)/spinel (shell) nanocubes with controllable size from 9 to 22 nm were synthesized by the decomposition of iron oleate complex at high temperature. The composition of the nanocubes was confirmed by X-ray diffraction and magnetic analysis, meanwhile the distributions of wustite and spinel phases within the nanocubes were directly observed by high resolution transmission electron microscopy using the dark-field image technique. The core/shell structure is quite unique, in which spinel phase is distributed not only preferentially on the surface, but also in the interior, while almost all of the wustite phase is located in the core of the nanocubes. The formation of wustite is inherent in the decomposition of the iron oleate complex, as indirectly inferred through the detection of a huge quantity of carbon monoxide generated from the reactor.