Magnetic properties of iron loaded MCM-48 molecular sieves

Mesoporous molecular sieves of MCM-48 type were loaded with iron by the wet impregnation method, using Fe(III) nitrate or Fe(II) sulfate aqueous solutions as Fe sources, to obtain a magnetic porous composite. The iron loaded materials were characterized by XRD, N 2 adsorption and DRUV-vis and compar...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 2010-11, Vol.322 (21), p.3438-3442
Main Authors: Elías, Verónica R., Oliva, Marcos I., Vaschetto, Eliana G., Urreta, Silvia E., Eimer, Griselda A., Silvetti, Silvia P.
Format: Article
Language:English
Subjects:
Clusters
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Cooling curves
Diamagnetism, paramagnetism and superparamagnetism
Domain effects, magnetization curves, and hysteresis
Exact sciences and technology
Ferromagnetism
Hysteresis loops
Iron
Iron oxide
Magnetic composite
Magnetic properties
Magnetic properties and materials
Magnetization
Magnetization curves, magnetization reversal, hysteresis, barkhausen and related effects
MCM-48
Mesoporous silica
Molecular sieves
Nonmetals
Physics
Sulfates
Superparamagnetic cluster
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Summary:Mesoporous molecular sieves of MCM-48 type were loaded with iron by the wet impregnation method, using Fe(III) nitrate or Fe(II) sulfate aqueous solutions as Fe sources, to obtain a magnetic porous composite. The iron loaded materials were characterized by XRD, N 2 adsorption and DRUV-vis and compared with the Si-MCM-48 host. Their magnetic properties were studied by measuring the hysteresis loops up to 1.5 T at different temperatures (5–300 K) and by magnetization vs. temperature curves following the conventional zero field cooling (ZFC) and field cooling (FC) protocols. Materials with high structure regularity and surface area are obtained, which exhibit a mixed paramagnetic and superparamagnetic behavior, arising in isolated iron ions inserted in the host framework, and in small iron oxide clusters or nanoparticles forming inside the pores, respectively. Larger hematite particles (8–13 nm) grown on the external surface provide a quite small ferromagnetic contribution to the hysteresis loop.
ISSN:0304-8853
DOI:10.1016/j.jmmm.2010.06.041