Quartz (SiO2) glass was implanted with 5 × 1016 57Fe ions/cm2 at a substrate temperature of 500 °C, and annealed at temperatures between 700 and 950 °C. The implanted and annealed plates
were characterized by conversion electron Mössbauer spectroscopy (CEMS), and measured by a Kerr effect magnetometer or a vibration
sample magnetometer. Kerr effect measurement of as-implanted SiO2 glass showed ferromagnetism at room temperature. CEM spectrum of the as-implanted glass consisted of magnetic relaxation
peaks of finely dispersed metallic Fe species, and paramagnetic doublets of Fe3+ and Fe2+ species. The sample heated at 700 °C contained large grains of metallic Fe and a lot of oxidation products of Fe2+ species. After oxidation at temperatures higher than 800 °C, the samples showed also ferromagnetism, which was attributed
mainly to ferromagnetic ε-Fe2O3 precipitated in SiO2 matrix. Small amounts of α-Fe2O3 were produced at 950 °C. The results suggest that ion implantation and oxidation make a transparent ferromagnetic glass possible.
Authors:C. Sikalidis, T. Zorba, K. Chrissafis, and K.M. Paraskevopoulos
Phase changes of iron containing solid wastes from steel mill pickling
lines after thermal treatments were investigated aiming the determination
of the appropriate conditions for its transformation to be useful for industrial
raw materials. Above 275°C, the thermally treated wastes contain a mixture
of α-Fe2O3 (hematite)
and γ-Fe2O3 (maghemite)
in different proportions, depending on the maximum heating temperature of
the thermal treatment. Increasing the maximum temperature the maghemite participation
is decreased through its transformation to hematite. Above 850°C hematite
is the main constituent, suggesting that thermal treatment of the wastes in
this temperature will give a product that could be used as red iron pigment.
X-ray, magnetic and differential thermal analysis and thermogravimetric (DTA-TG) measurements of Fe2O3 nanoparticles surrounded by amorphous SiO2were carried out. The mass loss above 370 K could be attributed to the dehydration. The broadened exothermic peak around 900
K was observed by the DTA analysis. Considering the results of the X-ray and magnetic analyses, this anomaly was interpreted
as due to the g- to a-transition in the present Fe2O3nanoparticle system. The broadness of the peak and thus the gradual progress of the transformation would be attributed to
the stress caused by the amorphous SiO2 network surrounding extremely small particles.
Summary Red mud is insoluble, fine-grained waste residue which is generated as a by product during the production of alumina from the Bayer process. In this article, the thermal behavior of Aughinish red mud was investigated using thermal gravimetric analysis (TG) and differential thermal analysis (DTA). For identification of oxide and mineral phases in the red mud sample, XRD method, scanning electron microscopy (SEM), EDAX were used. Iron (30.4%), aluminium (23.6%) and titanium (17.85%) oxides are major oxides in the sample. Two endothermic peaks were shown on DTA curve. The total mass loss in the red mud was found to be 10.1%, which was associated with moisture and water molecules in gibbsite and boehmite phases.
Authors:Laura Madalina Popescu, Roxana Mioara Piticescu, Maria Stoiciu, Eugeniu Vasile, and Roxana Trusca
, polyamidoamine (PAMAM)–Fe 2 O 3 nanocomposites have been developed for applications in nanomedicine [ 16 – 18 ]. Strable et al. [ 7 ] and Shi et al. [ 19 ] synthesized carboxyl-terminated PAMAM dendrimers–ironoxide nanocomposites by a template technique for
Authors:A. Oliveira, G. Marchetti, and M. Carmo Rangel
The effect of the iron precursor on the thermal decomposition of iron oxyhydroxides was studied by DSC, DTA and TG in this
work. Samples were prepared from iron nitrate, iron sulfate and iron chloride and the thermal curves obtained were analyzed
by specific area measurements, X-ray diffraction and Mssbauer spectroscopy. It was found that the iron oxyhydroxide precursors
affect the temperatures of the hematite formation as well as the textural properties of the final hematite producing particles
with different diameters as following: iron sulfate (3.3 nm)<iron nitrate (15 nm)<iron chloride (24 nm).
Authors:L. A. Perez-Maqueda, C. Maqueda, J. L. Perez-Rodriguez, J. Subrt, Z. Cerny, and V. Balek
solution, the amorphous silica transformation to cristobalite at about 950 °C is characterized by the decrease of the emanation rate E observed on heating. In the sample heated at 1200 °C the formation of composites of cristobalite and ironoxide has been