Topic
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, a comparative study of experimentally and naturally weathered pyrites was carried out, and it was found that both types of pyrites share similar species of weathering products and a similar weathering mechanism.
108 citations
TL;DR: In this paper, the authors reported on the preparation of magnetite nanoparticles, with size ranging from 12-nm to 20-nm, by high energy ball milling, using stoichiometric amounts of distilled water and metallic iron powder.
108 citations
TL;DR: In this paper, size-controlled magnetite nanoparticles (MNPs) with several dozen nanometers (nm) were synthesized for biomedical applications by oxidizing ferrous hydroxide (Fe(OH) 2 ) with a weak oxidant NaNO 3 in an N 2 -deaerated aqueous NaOH solution at various temperatures below 37°C.
108 citations
TL;DR: In this paper, a chemical coprecipitation process was used to synthesize about 7 nm, spherical magnetite nanoparticles to study magnetic properties and the aging effect, which can be applied to microbead applications of a biosensor.
Abstract: The chemical coprecipitation process was used to synthesize about 7 nm, spherical magnetite nanoparticles to study magnetic properties and the aging effect. As-produced spherical magnetite nanoparticles have been aged in the atmosphere for 19 months. Magnetic properties and aging effect were studied by Mossbauer spectroscopy at a temperature ranging from 77 to 300 K, vibrating sample magnetometer, and x-ray diffraction. Saturation magnetization and coercivity were found to be 49 emu/g and nearly 0 Oe at room temperature, respectively. A singlet Mossbauer spectrum was observed at room temperature, implying superparamagnetic behavior of the particles, while a two-sextet spectrum was observed at 77 K. The particle size in this study is about 7 nm, which is smaller than the superparamagnetic size of 26 nm as calculated from Neel’s theory of single domain particles. After having aged these particles for 19 months, all magnetic properties and their original shapes were retained. Superparmagnetic magnetite nanoparticles synthesized in this study can be applied to microbead applications of a biosensor.
107 citations
TL;DR: In this paper, the parabolic rate constants deduced from microbalance experiments were found to be in good agreement with the few existing values of the literature, and the presence of water vapor in air was found to strongly influence the transitory stages of the kinetics.
Abstract: The oxidation of iron has been studied at low temperatures (between 260 and 500 °C) in dry air or air with 2 vol% H2O, in the framework of research on dry corrosion of nuclear waste containers during long-term interim storage. Pure iron is regarded as a model material for low-alloyed steel. Oxidation tests were performed in a thermobalance (up to 250 h) or in a laboratory furnace (up to 1000 h). The oxide scales formed were characterized using SEM-EDX, TEM, XRD, SIMS and EBSD techniques. The parabolic rate constants deduced from microbalance experiments were found to be in good agreement with the few existing values of the literature. The presence of water vapor in air was found to strongly influence the transitory stages of the kinetics. The entire structure of the oxide scale was composed of an internal duplex magnetite scale made of columnar grains and an external hematite scale made of equiaxed grains. 18O tracer experiments performed at 400 °C allowed to propose a growth mechanism of the scale.
107 citations