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Magnetite
About: Magnetite is a research topic. Over the lifetime, 10277 publications have been published within this topic receiving 278071 citations.
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TL;DR: In this article, the process of obtaining highly dispersed magnetite by precipitation from a solution of iron salts in water by hydroxide is investigated by the magnetometric method and the traditional physico-chemical methods.
80 citations
TL;DR: In this paper, the reduction of titania-ferrous ore (ironsand) containing 57.2 wt% of iron and 7-8wt% of TO 2 was investigated in non-isothermal and isothermal reduction experiments using CO-CO 2 -Ar gas mixtures in a laboratory fixed bed reactor.
Abstract: The reduction of titania-ferrous ore (ironsand) containing 57.2 wt% of iron and 7-8wt% of TO 2 was investigated in non-isothermal and isothermal reduction experiments using CO-CO 2 -Ar gas mixtures in a laboratory fixed bed reactor. Samples in the course of reduction were characterised using XRD, EPMA and SEM. Two types of particles were identified in ironsand: 1) homogeneous particles of titano-magnetite with cubic spinel structure (a major type); and 2) non-homogeneous particles, characterised by lamellar structure of rhombohedral titano-hematite, exsoluted from the titano-magnetite. Titano-magnetite, which is a magnetite-ulvospinel solid solution (Fe 3 O 3 ) 1-x (Fe 2 TiO 4 ) x , with x=0.27±0.02, was reduced to metallic iron and titanium sub-oxides. Titanium had a strong effect on the mechanism and rate of reduction of iron oxide in ironsand.
80 citations
TL;DR: In this paper, a computer-controlled sputter-sectioning apparatus was used to measure the diffusion coefficient of 55Fe in the magnetite lattice as a function of oxygen activity at 500° C.
Abstract: A computer controlled sputter-sectioning apparatus is described which is particularly useful for self diffusion studies at “low” temperatures (D in the range 10−12 to 10−19cm2 sec−1). The technique has been applied to measure the diffusion coefficient of 55Fe in the magnetite lattice as a function of oxygen activity at 500° C. The results are in broad agreement with an extrapolation of pre-existing high temperature diffusion data (T>900°C). The low temperature data have been used to estimate the rate constant for magnetite formation on iron in CO2 + 1 vol% CO at 500° C and this is found to be 250 times smaller than the experimentally measured value. This disagreement is probably attributable to diffusion along oxide grain boundaries during oxidation. The rate constant for the formation of magnetite during the oxidation of iron in oxygen has also been calculated from the diffusion data and is compared with the measured rate constant for temperatures between 325 and 1100°C.
80 citations
TL;DR: In this paper, a study was performed to investigate dissolved organic matter (DOM) adsorption equilibrium using synthetic iron pipe corrosion scales ie goethite and magnetite for different pH values ranging from 25 to 105.
80 citations
TL;DR: A good correlation between susceptibilities measured in liquid samples at room temperature and the R2/RI ratio is demonstrated, and information on magnetic properties reported may help to characterize and to select these materials for use as MRI contrast agents.
Abstract: Superparamagnetic iron oxide particles, a new class of contrast agents for MRI, are extremely good enhancers of proton relaxation. However, the development of such particle systems has resulted in a wide range of preparations whose physico-chemical properties differ greatly. We have conducted a set of physical experiments: X ray diffraction analysis, relaxivity measurements, susceptibility determinations, and thermomagnetic cycling on different preparations of superparamagnetic particles. Our results demonstrate a good correlation between susceptibilities measured in liquid samples at room temperature and the R2/R1 ratio. Susceptibility measurements between liquid nitrogen temperature and room temperature show three different types of behavior dependent on the size of iron oxide crystals. Comparison of heating and cooling curves from strong field thermomagnetic cycles provides information about the maghemite/magnetite crystal content. The information on magnetic properties reported in this study may help to characterize and to select these materials for use as MRI contrast agents.
79 citations