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Abstract  

LiFe5O8 solid-phase synthesis at radiation-thermal (RT) annealing of lithium carbonate and iron oxide mechanical mixture was studied using thermal analysis (TG/DSC) and X-ray powder diffraction (XRD) techniques. The RT annealing was proceeded with high-power pulsing beam of 2.4 MeV electrons. It was shown that RT synthesis of the precursors considerably enhances the reactivity of the solid system within temperatures range 600–800 °C. In particular, lithium ferrite can be obtained at lower temperatures than those necessary in the absence of RT annealing.

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Abstract  

The aim of the present study was to determine the kinetic equations for the thermal transformations of precipitated iron oxides and hydroxides, namely for the process of thermal dehydroxylation of goethite and consecutive of hematite crystal structure growth as well as for the oxidation of magnetite to maghemite and its thermal transformation into crystalline hematite. The investigations have been carried out using thermogravimetry (TG/DTG/DTA), X-ray powder diffractometry (XRD) and high temperature powder diffractometry (HT-XRD). This presentation contains the continuation of our earlier works.

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The catalytic effects of metal oxides on thermal decomposition reactions, III

The influence of structural and electronic defects in iron oxides on their catalytic effectiveness with respect to the thermal decomposition of potassium chlorate

Journal of Thermal Analysis and Calorimetry
Authors: W. K. Rudloff and E. S. Freeman

The catalytic activity of a series of iron oxides on the thermal decomposition of potassium chlorate was investigated by methods of thermal analysis. Structural and electronic defects were introduced into the oxide by doping, heat treatment in different atmospheres, and irradiation withγ-rays. These induced defects changed in a systematic way the conductive properties of the iron oxides and correspondingly, their catalytic activity. The results are consistent with ann-type semiconductive behavior of the oxides.

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Abstract  

The paper presents studies on synthetic sinters of given basicities (CaO/SiO2 1.7–2.1). These multicomponent systems include not only doped iron oxides but calcium ferrites and numerous silicate phases as well. Investigatons were carried out by complex research methods, first of all by thermal analysis. Reduction processes of the sinters were observed by the methods of polythermal analysis in CO/CO2 atmosphere. The effect of mineral composition on physico-chemical properties of the sinters has been determined.

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Abstract  

Trace amount of nickel in high-purity iron and iron oxide samples was determined by photon activation analysis (PAA) using the Electron Linear Accelerator at the Research Center for Electron Photon Science, Tohoku University. It was confirmed that about 0.015 μg of nickel in the high-purity iron oxide sample could be determined with an experimental uncertainty of 20% by PAA, that is, it was possible to determine 1% of nickel at least in a few μg of cosmic spherules. PAA was applied to the nickel-determination in cosmic spherules. Nickel in cosmic spherules was determined by PAA more accurately than by instrumental neutron activation analysis done in a reactor neutron spectrum with the fluence rate ratio of thermal neutrons to fast of 4–5 which has so far been applied to the analysis of spherule samples. Additionally, trace amount of nickel in the reference material Giant Clam JCt-1 supplied by the Geological Survey of Japan was determined by PAA with radiochemical treatment.

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Abstract  

In this study, superparamagnetic iron oxide nanoparticles (SPION) embedded by folic acid (SPION-folate) were prepared by a modified co-precipitation method. The structure, size, morphology, magnetic property and relaxivity of the SPION-folate were characterized systematically by means of XRD, VSM, HRSEM and TEM and the interaction between folate and iron oxide (Fe3O4) was characterized by FT-IR. The particle size was shown to be ≈5–10 nm. To ensure biocompatibility, the interaction of these SPION with mouse connective tissue cells (adhesive) was investigated using an MTT assay. Consequently, gallium-67 labeled nanoparticles ([67Ga]-SPION-folate) were prepared using 67Ga with a high labeling efficiency (over 96%, RTLC method) and they also showed an excellent stability at room temperature for at least 2 days and were evaluated for their biodistribution in normal rats up to 24 h compared with free Ga3+ cation and [67Ga]-SPION biodistribution. The biodistribution of the tracer among 3 other folate tracers were compared, showing lower liver uptake and higher blood circulation after 24 h leading to better bioavailability. The bone:muscle, kidney:muscle, lung:muscle, stomach:muscle ratios were 9.3, 9.32, 7.6 and 5.83 respectively. The developed folate-containing nano-system can be an interesting folate receptor tracer, capable of better cell membrane permeability while possessing paramagnetic properties for thermotherapy.

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Abstract  

This work is focused on determination of the optimum firing temperature which leads to formation of the compounds LnFeO3 with good pigment-application properties (Ln=Gd, La, Yb, Tm, Lu). Based on results of thermal analysis the compounds were prepared by the solid-state reaction at temperature 900 and 1000°C. Colours of pigments vary depending on type of used lanthanoid (from light sienna to dark brown) and also on the type of precursor. Generally, the compounds prepared from iron oxide have more interesting color properties. Colour of these compounds is brighter and deeper. Increasing of the calcination temperature from 900 to 1000°C causes the darkening of colour. The most problably, the darkening is connected with partial reduction of Fe3+ to Fe2+.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: R. Dutta, M. Sudarshan, S. Bhattacharyya, V. Vijayan, S. Ghosh, V. Chakravortty, and S. Chintalapudi

Abstract  

Ferromanganese nodules found on the Ocean bed are complex heterogenous mixtures of several components. Two nodules from Central Indian Ocean Basin (CIOB) were analysed by proton induced X-ray emission (PIXE) technique using 3UD Tandem pelletron. The precision and the accuracy of this technique for chemical analyses has been confimed by analysing USGS Geological Standards. Thick sample targets were bombarded by 3 MeV protons for the multielemental analysis. GUPIX-96 software was used for spectral data analysis. Quantative estimate of K, Ca, Tl, V, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Rb, Sr, Y, Zr, Mo, Ba, Ce, Tl and Pb has been ascertained. The occurrence of Ga, Ge, Rb and Zr in nodules from this region is reported for the first time. The role of manganese and iron oxide phases in determining the uptake of various trace elements from ocean water and bottom sediment pore water has been discussed.

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Abstract  

A thermal analysis study on the reduction of iron oxide rich slags under different conditions is presented in this paper. The effects of important process variables such as time, temperature, lime-silica ratio, FeO level in slag etc. are discussed. It is shown that the mechanism of reduction by externally added graphite is different from that by a carbon saturated bath although the activation energy values are similar.

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Abstract  

Materials with high surface areas and small particle size (nanophases), metastable polymorphs, and hydrated oxides are increasingly important in both materials and environmental science. Using modifications of oxide melt solution calorimetry, we have developed techniques to study the energetics of such oxides and oxyhydroxides, and to separate the effects of polymorphism, chemical variation, high surface area, and hydration. Several generalizations begin to emerge from these studies. The energy differences among different polymorphs (e.g., various zeolite frameworks, the - and -alumina polymorphs, manganese and iron oxides and oxyhydroxides) tend to be small, often barely more than thermal energy under conditions of synthesis. Much larger contributions to the energetics come from oxidation-reduction reactions and charge-coupled substitutions involving the ions of basic oxides (e.g., K and Ba). The thermodynamics of hydration involve closely balanced negative enthalpies and negative entropies and are very dependent on the particular framework and cage or tunnel geometry.

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