Small iron oxide nanoparticles as MRI T1 contrast agent: scalable inexpensive water-based synthesis using a flow reactor

Small iron oxide nanoparticles (IONPs) were synthesised in water via co-precipitation by quenching particle growth after the magnetic iron oxide phase formed.

Thermal phase design of ultrathin magnetic iron oxide films: from Fe3O4 to γ-Fe2O3 and FeO

Thermodynamically “active” oxide interfaces alter the standard iron oxide phase diagram of complex heterostructures. By controlling the effective oxygen pressure, selected iron oxides phases can be designed through a thermal phase design.

Laser Vaporization of Magnetic FexOy and FexOy-SiO2 Nanoparticles for Biomedical Applications

Magnetic iron oxide (FexOy) and iron oxide/silica (FexOy/SiO2) composite nanoparticles were synthesized by CO2 laser vaporization (LAVA) of an α-Fe2O3 raw powder and α-Fe2O3/quartz sand mixtures, respectively. Particle morphology, composition and iron oxide phase formation were investigated by transmission electron microscopy and X-ray diffraction. The resulting nanopowders mainly consisted of magnetite (Fe3O4) and maghemite (γ-Fe2O3). Increasing the oxygen partial pressure in the LAVA process gas an additional iron oxide phase, ε-Fe2O3, occurred. The saturation magnetization of the iron oxide nanoparticles was determined with vibrating sample magnetometry and was found to decrease with increasing oxygen partial pressure in the process gas. FexOy/SiO2 composite nanoparticles are of particular interest for biomedical applications because their silica surface can be functionalized very easily.

Functionalisation of Glass with Iron Oxide Nanoparticles Produced by Laser Pyrolysis

In the present work, a new process for depositing nanoparticle layers onto glass has been developed by using one of the most interesting nanoparticle generation technologies at the moment, which is based on the pyrolysis induced by laser of vapours combined with CVD of the particles onto glass. Nanoparticles prepared by this method were deposited into a hot silica substrate obtaining new nanocomposites with unique properties. The coated glasses present new specific functionalities such as colour, and interesting magnetic and optical properties. Control of the thickness and the iron oxide phase, either magnetic or not, has been achieved by adjusting the experimental conditions. Thus, thickness is controlled by the glass and the precursor temperature, while the iron phase is controlled by the precursor temperature and the nature and the flow of the carrier gas. This process is inexpensive, adaptable to current glass production technologies and takes place at atmospheric pressure.

Le magmatisme de la région de Kwyjibo, Province du Grenville (Canada) : intérêt pour les minéralisations de type fer-oxydes associées

The granitic plutons located north of the Kwyjibo property in Quebec's Grenville Province are of Mesoproterozoic age and belong to the granitic Canatiche Complex . The rocks in these plutons are calc-alkalic, K-rich, and meta- to peraluminous. They belong to the magnetite series and their trace element characteristics link them to intraplate granites. They were emplaced in an anorogenic, subvolcanic environment, but they subsequently underwent significant ductile deformation. The magnetite, copper, and fluorite showings on the Kwyjibo property are polyphased and premetamorphic; their formation began with the emplacement of hydraulic, magnetite-bearing breccias, followed by impregnations and veins of chalcopyrite, pyrite, and fluorite, and ended with a late phase of mineralization, during which uraninite, rare earths, and hematite were emplaced along brittle structures. The plutons belong to two families: biotite-amphibole granites and leucogranites. The biotite-amphibole granites are rich in iron and represent a potential heat and metal source for the first, iron oxide phase of mineralization. The leucogranites show a primary enrichment in REE (rare-earth elements), F, and U, carried mainly in Y-, U-, and REE-bearing niobotitanates. They are metamict and underwent a postmagmatic alteration that remobilized the uranium and the rare earths. The leucogranites could also be a source of rare earths and uranium for the latest mineralizing events.[Traduit par la Rédaction]

Evidence for the multiphase nature of bentonites from Mössbauer and EPR spectroscopy

Mössbauer spectra of several smectites demonstrate the existence of at least three phases with distinct Fe populations: (i) a component with very low Fe content (< 1%), which shows slowly-relaxing paramagnetic hyperfine structure at both 4·2 K and 77 K; (ii) a component with intermediate Fe content (∼ 1–10%) which is seen as doublets in the spectra at 4·2 K, 77 K and ambient temperature; (iii) an Fe-rich phase (> 30% Fe), which shows magnetic ordering at 4·2 K and 77 K. These data are consistent with components (i) and (ii) corresponding to Fe incorporated in aluminosilicate structures from distinct phases, whereas (iii) is characteristic of an iron oxide phase, probably goethite in most cases. These conclusions are supported by EPR measurements which show magnetically-dilute Fe in more than one type of structural environment plus an additional component with magnetically-interacting ions.