Magnetite

About: Magnetite is a research topic. Over the lifetime, 10277 publications have been published within this topic receiving 278071 citations.

Preparation and magnetic properties of magnetite nanoparticles by sol-gel method

Abstract: Magnetite (Fe 3 0 4 ) nanoparticles have been synthesized by sol-gel method combined with annealing under vacuum, without use of surfactants and using precursors like FeCl 3 ·6H 2 0, ethanol and propylene epoxide and using several annealing temperatures and different annealing time. The approach is straightforward, inexpensive and versatile. The annealing process, the phase structures, morphologies, particle sizes and magnetic properties of Fe 3 0 4 nanoparticles have been characterized by thermogravimetric-differential thermal analysis (TG-DTA), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometer (VSM). The results indicate that with annealing at 300°C for 2h under vacuum, magnetite (Fe 3 0 4 ) nanoparticles in the interval of 9∼11nm were synthesized and that the six, the corresponding saturation magnetization value and coercivity value of Fe 3 0 4 nanoparticles increase with the increase of synthesized temperature. In addition it is possible to obtain a narrower nanoparticle size dispersion and smaller naoparticles for shorter annealing time under vacuum and this method could be extended to prepare other transition and main-group metal oxide materials.

Aeromagnetic anomalies, magnetic petrology, and rock magnetism of hemo-ilmenite- and magnetite-rich cumulate rocks from the Sokndal Region, South Rogaland, Norway

Abstract: Aeromagnetic maps of the Egersund Mid-Proterozoic igneous province show a spectacular range of positive and negative magnetic anomalies with a contrast up to 15 600 nT. The positive magnetic anomalies are over magnetite norites and overlying mangerites and quartz mangerites of the Bjerkreim-Sokndal layered intrusion. These rocks are dominated by multi-domain (MD) magnetite. The negative magnetic anomalies are over ilmenite-rich norites of the Bjerkreim-Sokndal layered intrusion, the Tellnes ilmenite norite ore deposit, and massif anorthosites. These rocks are dominated by hemo-ilmenite and/or by silicates containing fine-grained oxide exsolution lamellae. Electron microprobe analyzes of coexisting Fe-Ti oxides in the layered intrusion confirm earlier observations that oxides in early magmatic rocks are dominated by hemo-ilmenite with minor end-member magnetite, followed by more reduced oxides dominated by titanomagnetite with minor near end-member ilmenite. What is not fully understood is the property of ilmenite with hematite exsolution lamellae, or, even more striking, hematite with ilmenite lamellae, to produce strong remanent magnetization of high coercivity and with a Neel temperature equal to or above the Curie temperature of magnetite. This property makes the rhombohedral oxides an important candidate to explain some high-amplitude deep-crustal anomalies on earth, or strong remanent magnetization on other planets. A remarkable feature in the Egersund province is that primitive magmas produced rocks rich in hemo-ilmenite causing negative magnetic anomalies related to magnetic remanence, and more evolved magmas produced rocks rich in magnetite related to positive induced magnetic anomalies, all in the course of crystallization-differentiation.

Lanthanide(III)-Doped Magnetite Nanoparticles

Abstract: Nearly monodisperse lanthanide-doped magnetite nanoparticles were obtained by thermally decomposing a mixture of Fe(acac)3 and Ln(acac)3 (acac = acetylacetonate; Ln = Sm, Eu, Gd) in the presence of passivating surfactants. Magnetic studies revealed room-temperature ferromagnetic behaviors of these doped nanoparticles, distinctly different from those of the undoped parent magnetite or the doped nanoparticles prepared by a coprecipitation method.