Influence of Growth Conditions on Magnetite Nanoparticles Electro-Crystallized in the Presence of Organic Molecules

Saba Mosivand,Lorena Monzon,J Coey,Iraj Kazeminezhad

doi:10.3390/ijms140510383

Abstract

Magnetite nanoparticles were synthesized by electrocrystallization in the presence of thiourea or sodium butanoate as an organic stabilizer. The synthesis was performed in a thermostatic electrochemical cell containing two iron electrodes with an aqueous solution of sodium sulfate as electrolyte. The effects of organic concentration, applied potential and growth temperature on particle size, morphology, structure and magnetic properties were investigated. The magnetite nanoparticles were characterized by X-ray diffraction, electron microscopy, magnetometry and Mössbauer spectrometry. When the synthesis is performed in the presence of sodium butanoate at 60 °C, a paramagnetic ferric salt is obtained as a second phase; it is possible to avoid formation of this phase, increase the specific magnetization and improve the structure of the oxide particles by tuning the growth conditions. Room-temperature magnetization values range from 45 to 90 Am2kg−1, depending on the particle size, type of surfactant and synthesis conditions. Mössbauer spectra, which were recorded at 290 K for all the samples, are typical of nonstoichiometric Fe3−δO4, with a small excess of Fe3+, 0.05 ≤ δ ≤ 0.15.

Highlights

In the last decade, magnetic nanostructures have attracted great attention because of their special properties, which differ significantly from those of the bulk materials
The results of our study on the effect of the experimental conditions on structural and magnetic properties of electrocrystallized magnetite nanoparticles in the presence of different organic molecules show that temperature, voltage and concentration all play a significant role in determining the morphological, structural, and magnetic properties of the nanoparticles produced
The particle size and morphology were found to be modified by the concentration of organic agent, applied potential, or the temperature of the bath

Summary

Introduction

Magnetic nanostructures have attracted great attention because of their special properties, which differ significantly from those of the bulk materials. Co-precipitation is one of the simplest and oldest techniques and the most common production method This method usually generates particles with a wide particle size distribution, and may require secondary size selection [25]. Another difficulty in synthesizing Fe3O4 nanoparticles by chemical co-precipitation is the strong tendency of the particles to oxidize to αFe2O3, thereby greatly reducing their magnetization. We have found that the structural properties of electro-oxidized Fe3O4 nanoparticles are affected by the stabilizer concentration [29], and that the specific magnetization (σs) of magnetite can be controlled by the capping agent [30]. We analyze the relationship between growth conditions, specific magnetization and particle size, which is largely dependent on the concentration of organic molecules

XRD Results

Particle Size Distribution and Morphology

Magnetic Properties

Mössbauer Spectroscopy

Methods

Conclusions