1 research outputs found
Superparamagnetic MFe<sub>2</sub>O<sub>4</sub> (M = Fe, Co, Mn) Nanoparticles: Tuning the Particle Size and Magnetic Properties through a Novel One-Step Coprecipitation Route
Superparamagnetic ferrite nanoparticles (MFe<sub>2</sub>O<sub>4</sub>, where M = Fe, Co, Mn) were synthesized through a novel
one-step
aqueous coprecipitation method based on the use of a new type of alkaline
agent: the alkanolamines isopropanolamine and diisopropanolamine.
The role played by the bases on the particlesā size, chemical
composition, and magnetic properties was investigated and compared
directly with the effect of the traditional inorganic base NaOH. The
novel MFe<sub>2</sub>O<sub>4</sub> nanomaterials exhibited high colloidal
stability, particle sizes in the range of 4ā12 nm, and superparamagnetic
properties. More remarkably, they presented smaller particle sizes
(up to 6 times) and enhanced saturation magnetization (up to 1.3 times)
relative to those prepared with NaOH. Furthermore, the nanomaterials
exhibited improved magnetic properties when compared with nanoferrites
of similar size synthesized by coprecipitation with other bases or
by other methods reported in the literature. The alkanolamines were
responsible for these achievements by acting both as alkaline agents
and as complexing agents that controlled the particle size during
the synthesis process and improved the spin rearrangement at the surface
(thinner magnetic ādeadā layers). These results open
new horizons for the design of water-dispersible MFe<sub>2</sub>O<sub>4</sub> nanoparticles with tuned properties through a versatile and
easily scalable coprecipitation route