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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: Raman spectral features of chromite, ulvospinel, magnetite, ilmenite, hematite, and some of their solid solutions are presented in this article, where the relationship between Raman spectral features and mineral chemistry is used to interpret the Raman data of Fe-Ti-Cr oxides found during Raman point-count measurements on rock chips of Martian meteorite EETA79001.
Abstract: Raman spectral features of chromite, ulvospinel, magnetite, ilmenite, hematite, and some of their solid solutions are presented. Although most Fe-Ti-Cr-oxides produce relatively weak Raman signals compared to oxyanionic minerals, sufficient information can be extracted from their spectra to identify the end-member mineral phases as well as some information about compositional variations in solid solutions. Correlations between Raman spectral features and mineral chemistry are used to interpret the Raman data of Fe-Ti-Cr oxides found during Raman point-count measurements on rock chips of Martian meteorite EETA79001, as an analog to Mars on-surface planetary investigations. In general, ulvospinel, magnetite, and chromite end-members are readily distinguished by their Raman spectral patterns, as are ilmenite and hematite. In the low signal-to-noise (S/N) spectra generally obtained from the Raman point-count procedure, the position and shape of the strongest peak of Fe-Ti-Cr oxides in the region 660–680 cm−1 (A1g mode) is the most useful for discriminating Fe3+-Ti-Cr-Al substitutions in the magnetite-ulvospinel, ulvospinel-chromite, and chromite-spinel series, but minor peaks in the range 300–600 cm−1 also assist in discrimination. These spectral features are useful for investigating the variability among Fe-Ti-Cr-Al oxide solid solutions in natural samples. In EETA79001, a Martian basaltic meteorite, most of the oxide grains (as measured with the electron microprobe) are ulvospinel, chromian ulvospinel, and chromite, but ilmenite, titanian chromite, and titanomagnetite are also observed. The Fe-Ti-Cr-oxides identified by Raman point-count include end-member ilmenite, low-Al chromite-spinel solid solutions, ulvospinel-magnetite solid solutions, and more complex chromite-spinel-ulvospinel-magnetite solid solutions; the latter exhibit a wide range of main peak positions and broadened peak widths that may reflect structural disorder as well One Raman spectrum suggests end-member magnetite, and one spectrum from a different rock chip appears to be that of non-terrestrial hematite, reflecting local oxidizing alteration, which has not been observed previously in this meteorite. These results show that analyses done in an automated mode on the surface of an unprepared Martian rock sample can provide useful constraints on the Fe-Ti-Cr oxide mineralogy present and on compositional variations within those minerals, including an indication of oxygen fugacity.
190 citations
TL;DR: In this paper, a new effective adsorbent for removal of some heavy metal ions such as Fe, Pb, Zn, Ni, Cd and Cu from aqueous solution is synthesized by pulsed current electrochemical method.
190 citations
TL;DR: The rate of removal was sufficiently rapid such that the initial presence of Fe2O3 at the iron surface would have no consequence with respect to the performance of an in situ wall, and magnetite and green rust formed at theIron surface as a result of corrosion in both the Millipore water and the solution containing TCE.
190 citations
TL;DR: In primary mouse experiments, drug-entrapped magnetic nanoparticles showed good biocompatibility and effective therapy for spinal cord damage, and are attractive candidates for widespread biomedical applications, particularly in controlled drug-targeting delivery.
Abstract: In this study, temperature-responsive magnetite/polymer nanoparticles were developed from iron oxide nanoparticles and poly(ethyleneimine)-modified poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymer. The particles were characterized by TEM, XRD, DLS, VSM, FTIR, and TGA. A typical product has an approximately 20 nm magnetite core and an approximately 40 nm hydrodynamic diameter with a narrow size distribution and is superparamagnetic with large saturation magnetization (51.34 emu/g) at room temperature. The most attractive feature of the nanoparticles is their temperature-responsive volume-transition property. DLS results indicated that their average hydrodynamic diameter underwent a sharp decrease from 45 to 25 nm while evaluating the temperature from 20 to 35 degrees C. The temperature-dependent evolution of the C-O stretching band in the FTIR spectra of the aqueous nanoparticles solution revealed that thermo-induced self-assembly of the immobilized block copolymers occurred on the magnetite solid surfaces, which is accompanied by a conformational change from a fully extended state to a highly coiled state of the copolymer. Consequently, the copolymer shell could act as a temperature-controlled "gate" for the transit of guest substance. The uptake and release of both hydrophobic and hydrophilic model drugs were well controlled by switching the transient opening and closing of the polymer shell at different temperatures. A sustained release of about 3 days was achieved in simulated human body conditions. In primary mouse experiments, drug-entrapped magnetic nanoparticles showed good biocompatibility and effective therapy for spinal cord damage. Such intelligent magnetic nanoparticles are attractive candidates for widespread biomedical applications, particularly in controlled drug-targeting delivery.
190 citations
TL;DR: In this paper, nearly monodisperse magnetite nanoparticles with sizes less than 10 nm have been successfully deposited on multi-walled carbon nanotubes (MWNTs) by in situ high-temperature decomposition of the precursor iron(III) acetylacetonate and MWNTs in polyol solution.
Abstract: Nearly monodisperse magnetite nanoparticles with sizes less than 10 nm have been successfully deposited on multi-walled carbon nanotubes (MWNTs) by in situ high-temperature decomposition of the precursor iron(III) acetylacetonate and MWNTs in polyol solution. The effects of the concentration of the iron precursor on the ultimate nanocomposites characteristics were investigated. XRD, TEM, HRTEM, EDS, and PPMS of Quantum Design were used to characterize the final products. It was found that the sizes of nanoparticles and their coverage density on MWNTs could be easily controlled by changing the concentration of the precursor and the weight radio to MWNTs. A possible formation mechanism of the magnetite–MWNT nanocomposites was suggested. It was concluded that the magnetite nanoparticles formation on MWNTs through an aggregation process of subparticles that is influenced strongly by the presence of polyols. Magnetic measurements showed that the nanocomposites are superparamagnetic at room temperature and the magnetization of the samples is strongly influenced by the reaction conditions. The resulting nanomaterials can be easily dispersed in water and can be manipulated by an external magnetic field. As-synthesized nanocomposites have high potential for applications in the fields of composites, wastewater treatment, sensors, and biomaterials.
190 citations