Ultraporous single phase iron oxide-silica nanostructured aerogels from ferrous precursors.
Monoliths of iron oxide-silica aerogel nanocomposites have been synthesized using a novel synthesis route which consists of impregnating silica wet gels with anhydrous iron(II) precursors followed by ethanol supercritical drying of the gels. The process yields aerogels exhibiting high porosity, large surface areas (approximately 900 m2/g), rather low densities (approximately 0.6 g/cm3), and a homogeneous distribution of single-phase maghemite, gamma-Fe2O3, nanoparticles with average sizes in the 7-8 nm range. Remarkably, the gamma-Fe2O3 nanoparticles are obtained in the as-dried state without the need of postannealing. The nanoparticles are mostly superparamagnetic at room temperature but become blocked in a ferrimagnetic state at lower temperatures.
Popovici
Mihaela
M
Institut de Ciència de Materials de Barcelona, Campus Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalunya, Spain.
Gich
Martí
M
Roig
Anna
A
Casas
Lluís
L
Molins
Elies
E
Savii
Cecilia
C
Becherescu
Dumitru
D
Sort
Jordi
J
Suriñach
Santi
S
Muñoz
Juan S
JS
Baró
M Dolors
MD
Nogués
Josep
J