Tuning the Magnetic Properties of Iron Oxide Nanoparticles by a Room-Temperature Air-Atmosphere (RTAA) Co-Precipitation Method

Abstract

The ability of a room-temperature air-atmosphere (RTAA) co-precipitation method to tune the magnetic properties of iron oxide nanoparticles was investigated. It was demonstrated that superparamagnetic nanoparticles with different particle sizes ranging from 7 to 25 nm and magnetic properties with saturation magnetization between 2 to 75 emu g(-1) can be synthesized by simply controlling the molar ratio of ferrous to ferric ions and the concentration of ammonium solution, without heat treatment or oxygen-level control. It was revealed that the tuning of the magnetic properties was associated with the compositional control between magnetite and maghemite. Ammonium concentration was also an important factor to obtain dispersed superparamagnetic (SPM) or ferrimagnetic (FM) nanoparticles.

A comparative study: Synthesis of superparamagnetic iron oxide nanoparticles in air and N 2 atmosphere

“…In the previous studies, it was stated that when Fe 2+ /Fe 3+ ions with a 3/1 ratio was used in the synthesis under air atmosphere, higher saturation magnetization (Ms) values were obtained for spherical Fe3O4 nanoparticles [23]. Different to such reports, we found that the presence of iron oxide nanoflakes were observed for the same Fe 2+ /Fe 3+ ratio in air atmosphere, as seen in Fig.…”

“…It has been previously shown by Vikram et al that saturation magnetization and particle size can be changed by varying the molar ratio of Fe 2+ to Fe 3+ ions and concentration of base in air atmosphere [23]. It has also been shown that smaller particle size and improved magnetic properties could be obtained by changing the base used [24].…”

High-resolution analytical imaging and electron holography of magnetite particles in amyloid cores of Alzheimer’s disease

“…The magnetic response of iron oxide is related to nanoparticle size; specifically the critical diameter for single domain particle formation ( D sd ) of Fe 3 O 4 is ~80 nm at room temperature 58 . Whereas, particles of smaller size (25–30 nm) approach the lower critical diameter for superparamagnetic response ( D sp ) characterized by a fast flipping of the magnetization vectors presenting vanishing magnetization values 58 59 . Micromagnetic simulations of the equilibrium magnetization of Fe 3 O 4 particles were computed to analyze the direct visualizations by holography.…”

Study of Tool Wear Properties Using Magnetorheological Fluid Damper

“…The surfactant used was fine white Lithium grease, the grease was thoroughly mixed with carrier oil for around 2 h and then the carbonyl-iron particles were added to the mixture and were well stirred for another one h. Hence, we could obtain a homogenous mixture of MR fluid. Preparation of magneto-rheological fluid is explained in article (Vikram, 2014). It was decided to arrive at a set of MR fluid damper parameters namely the shape of the plunger (S), the viscosity index of the fluid medium (p) , size of the ferro magnetic particle (m) and the current through the coil(I) to minimize tool vibration.…”