The conversion of magnetite to maghemite has been studied kinetically in the ultrafine particle range (77-220A) by chemical analysis. X-ray diffraction, and Mossbauer measurements. The reaction is third order. The activation temperatures are relatively low (8 250-1 1 200 K). Electron hopping in ultrafine magnetite powders is discussed on the basis of the results.

BACKGROUND We have developed magnetic cationic liposomes (MCLs) that contained magnetic nanoparticles as heating mediator for applying them to local hyperthermia. The heating performance of the MCLs is significantly affected by the property of the incorporated magnetite nanoparticles. We estimated heating capacity of magnetite nanoparticles by measuring its specific absorption rate (SAR) agains...

In the present study, a new magnetic powder based on magnetite can be used as a petroleum crude oil collector. Amidoximes based on rosin as a natural product can be prepared from a reaction between hydroxylamine and rosin/acrylonitrile adducts. The produced rosin amidoximes were used as capping agents for magnetite nanoparticles to prepare hydrophobic coated magnetic powders. A new class of mon...

ÐShape fabric and distribution anisotropy of magnetite grains in a highly ferromagnetic (s.l.) syenite are determined for three mutually perpendicular planes on about 600 magnetite grains. The grains are lenticular with an average aspect ratio of about 2.0. Their preferred orientation, determined by the inertia tensor method, is consistent with the principal directions of the magnetic susceptib...

We studied 27 large (>400 µm) iron-type (I) cosmic spherules (made essentially of magnetite and wustite) representative of the Transantarctic Mountains collection [1], together with 5 G-type (G) spherules (made of iron oxides and silicates in similar proportions). They were characterized by magnetic and density measurements, SEM imaging and microprobe analysis of polished sections. Presence of ...

Arsenic sorption onto iron oxide spinels such as magnetite could contribute to immobilization of arsenite (AsO3(3-)), the reduced, highly toxic form of arsenic in contaminated anoxic groundwaters, as well as to putative remediation processes. Nanocrystalline magnetite (<20 nm) is known to exhibit higher efficiency for arsenite sorption than larger particles, sorbing as much as approximately 20 ...

We report dynamic alternation of the redox chemistry of the Fe/ Fe couple in magnetite during high temperature water−gas shift reaction in Cu codoped Mmodified ferrite catalysts. Various hematitic solid solutions of the type Fe2O3−MxOy−CuOx with M = Cr, Ce, Ni, Co, Mn, and Zn are synthesized using the industrially economical and environmentally friendly coprecipitation method. Interestingly, Cu...

A 1500-m-thick Cenozoic sequence was recovered in a series of 3 drill holes from the Victoria Land Basin, Antarctica, in association with the Cape Roberts Project. The CRP-3 drill hole penetrated the oldest Palaeogene strata in the Granite Harbour region and terminated in strata from the Devonian Beacon Supergroup. The upper 823-m of the CRP-3 drill-core is an expanded sequence that may span th...

Thin-films of magnetite, F@04 have been produced by the XeCl excimer laser ablation of both Fe304 and metallic Fe targets. The ablation of metallic Fe has been shown to produce about two orders of magnitude smaller concentration of boulders than the ablation of bulk magnetite. The use of single-crystal, latticematching substrates was found to be necessary at lower fluences (1 3 J cm-') for the ...