Temperature dependent properties and aggregation behaviour of FeCo nanoparticles produced sonoelectrochemically

The study describes synthesis of FeCo nanoparticles by using the pulsed sonoelectrochemical technique, a method which couples an electrochemical process with the employment of high power ultrasound. An ultrasonic horn is also used as the working electrode and is subjected to a pulsed galvanic current and pulsed out of phase ultrasound. Nanoparticles made of FeCo alloy were synthesized at different bath temperatures, in order to study and evaluate the influence of this parameter on process efficiency and nanoparticles' features. Produced material was characterized by X-EDS, X-Ray diffraction, and finally by transmission electron microscopy. Moreover characterization of nanoparticles' tendency to aggregation was performed with dynamic light scattering and by using a polyacrilate to stabilize the suspensions. Process efficiency was found to be strongly influenced by temperature, and from chemical analyses, a preferential deposition of iron was observed, due to the lower iron reduction overpotential. Structural characterization stated that FeCo nanoparticles showed a bcc structure and a mean grain size below 30 nm, which depended on synthesis temperature (T) and decreased with T to 5 nm. TEM characterization showed that nanoparticles exhibited the same mean dimensions like ones found from XRD analyses; this led to conclude that nanopowders are monocrystalline.