Fe 2

Magnetic nanocomposites exhibit promising applications in many areas, for example optics, electronics, biology, medicine, etc. The main goal of this study was to synthesize magnetic ε-$Fe_2O_3$ nanoparticles embedded in amorphous $SiO_2$. These materials were prepared by the help of ultrasonic activation and subsequent annealing in nitrogen atmosphere or air with concentrations of iron oxide of about 20 and 30 wt.%. The structure and properties of the final product were analysed by the Mössbauer spectrometry as well as by X-ray diffraction, scanning electron microscopy, and high resolution transmission electron microscopy. They strongly depend on the initial conditions of preparation

Fe2O3/SiO2Fe_2O_3/SiO_2 Hybrid Nanocomposites Studied Mainly by Mössbauer Spectroscopy

Magnetic nanocomposites exhibit promising applications in many areas, for example optics, electronics, biology, medicine, etc. The main goal of this study was to synthesize magnetic ε-$Fe_2O_3$ nanoparticles embedded in amorphous $SiO_2$. These materials were prepared by the help of ultrasonic activation and subsequent annealing in nitrogen atmosphere or air with concentrations of iron oxide of about 20 and 30 wt.%. The structure and properties of the final product were analysed by the Mössbauer spectrometry as well as by X-ray diffraction, scanning electron microscopy, and high resolution transmission electron microscopy. They strongly depend on the initial conditions of preparation

Mössbauer studies on ultraporous Fe-Oxide/SiO2 aerogel

Magnetic aerogels with very low volume density of ∼0.2 g/cm3 were prepared by sol-gel method and supercritical drying. The resulting materials were monolithic and displayed high surface area. By X-ray diffraction and Mössbauer spectroscopy the crystalline phase formed inside the mesopores of the SiO2 matrix was identified as a spinel iron oxide. Comparison of the magnetic measurements with Mössbauer spectra at various temperatures contributed to the elucidation of the magnetic state of this nanocomposite system with restricted magnetic interactions, in particular its transition to a superparamagnetic state

Mössbauer studies of magnetic Fe2O3/SiO2 nanocomposites

Suppl. E (2006): Proceedings of the International Colloquium "Mössbauer Spectroscopy in Materials Science" (June 11–15, 2006, Kočovce, Slovak Republic)A large variety of glass and glass ceramics may be obtained by sol-gel process from hydrolysis of tetraethoxysilane. The transformation involves hydrolysis and polycondensation reactions leading to the growth of clusters that eventually collide together to form a gel. The structure and properties of the final product have been found to be strongly dependent on the initial conditions of preparation. Silica nanocomposites based on Fe2O3/SiO2 were prepared with the help of ultrasonic activation and subsequent annealing in nitrogen atmosphere or air with concentrations of iron oxide of about 20 to 30wt.%

From nanocrystals to nanorods: new iron oxide−silica nanocomposites from metallorganic precursors

Sol-gel one-step processing of the Fe(II) alkoxide Fe(OBut)2(THF)2 and tetraethyl orthosilicate (TEOS) at various ratios afforded new silica-iron oxide magnetic nanocomposite materials, ranging in shape from nanocrystals to nanorods depending on the percentage of TEOS added. The nanocomposites have been investigated by Fourier transform infrared and Raman spectroscopy, X-ray diffraction, 57Fe Mossbauer spectroscopy, magnetization measurements, transmission electron microscopy, scanning transmission electron microscopy, and energy dispersive X-ray analysis. These silica-coated magnetic materials might have a range of potential applications in biotechnology, medicine (e.g., as magnetic fluids for MRI), catalysis, and magnetic storage