Iron-containing nanocomposites based on mesoporous aluminosilicates

Here we report the synthesis and magnetic characterization of iron-containing nanocomposites based on mesoporous aluminosilicates (MAS). MAS with Al:Si ratio equal to 1:15 was synthesized by a two-step hydrothermal treatment. The chemical composition and structure of the matrix were determined by chemical analysis, TGA, SAXS and adsorption of nitrogen at 77 K. The intercalation of iron into the channels was performed either by cationic exchange or by soaking the initial matrix in Fe(CO)5. Reduction/decomposition of the complex was carried out by thermal treatment in a hydrogen flow. The nanocomposites obtained were characterized by XRD, TEM, Mössbauer spectroscopy and magnetic measurements. It was shown that the first method does not give any magnetic phases at nanolevel. The second method results in the formation of magnetic iron-containing nanowires (with diameter <2 nm and length over 30 nm) in a mesoporous matrix, which possess blocking temperatures over 300 K and coercivity up to 31,000 A/m at room temperature.