Fibres-based soft magnetic composites (FSMCs) have been prepared by using Fe fibres of different diameters (65, 125, 250 and 500 μm). The Fe fibres were coated with a 3 μm thick layer of Fe3O4 via the blackening process and subsequently compacted at 700 MPa. The X-ray diffraction analysis (XRD) was used to prove the formation of the Fe3O4 coating on the surface of the fibres. The thickness and the uniformity of the coating were analysed via scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The DC measurements performed on the composite cores revealed that the saturation induction increase from 1.36 to 1.68 T, the maximum relative permeability increase from 550 to 940, and the coercive field decrease from 796 to 454 A/m as the fibre's diameter increase from 65 to 500 μm. By using thinner fibres (65 and 125 μm), composites with low losses and stable initial relative permeability, in the frequency range 50 Hz–10 kHz, can be obtained. To distinguish between different types of losses dissipated by our compacts, and the influence of the fibre's diameter on the different components of the total losses, a numerical model for loss separation is proposed. The comparative evolution of the AC magnetic characteristics of the FSMCs and powder-based SMCs is presented. According to the presented results, this new type of composites can be successfully used to prepare magnetic cores designated to work in the medium to high-frequency range. 相似文献
Bifunctional monodispersed Fe3O4 particles coated with an ultrathin Y2O3:Tb3+ shell layer were fabricated using a facile urea-based homogeneous precipitation method. The obtained composite particles were characterized by powder X-ray diffraction, transmission electron microscopy (TEM), quantum design vibrating sample magnetometry, and photoluminescence (PL) spectroscopy. TEM revealed uniform spherical core-shell-structured composites ranging in size from 306 to 330 nm with a shell thickness of approximately 25 nm. PL spectroscopy confirmed that the synthesized composites displayed a strong eye-visible green light emission. Magnetic measurements indicated that the composite particles obtained also exhibited strong superparamagnetic behavior at room temperature. Therefore, the inner Fe3O4 core and outer Y2O3:Tb3+ shell layer endow the composites with both robust magnetic properties and strong eye-visible luminescent properties. These composite materials have potential use in magnetic targeting and bioseparation, simultaneously coupled with luminescent imaging. 相似文献
In this paper, Fe3O4 nanoparticles coated with titanium silicalite-1 (designated Fe3O4@TS-1) were successfully prepared and used as catalysts for ammoximation of cyclohexanone. Characterizations demonstrated that the magnetic catalyst was coated with a thin TS-1 layer of ~ 30 nm in thickness. The catalyst still displayed excellent catalytic activity after introducing Fe3O4 core. Recovery experiments revealed that Fe3O4@TS-1 catalyst could be easily recovered by adding an external magnetic field. Moreover, no appreciable catalytic deactivation was observed after four times of recycling. This work provided a promising way to overcome the recycle problem during the application of TS-1. 相似文献
Heterogeneous Fe3O4@TiO2@Au core-shell microspheres, a facile and highly efficient catalyst have been fabricated by a simple surface modification. The fabrication process involved the coating of TiO2 nanoshell onto the magnetic core using by sol-gel process, and then the anchoring of Au nanoparticles onto the surface of the Fe3O4@TiO2 microspheres through the wet chemical reaction of 3-aminopropyltriethoxysilane (APTES). The as-synthesized Fe3O4@TiO2 microspheres exhibited a narrow size distribution, with a typical size of 350 nm and shell thickness of 25 nm. The Fe3O4@TiO2@Au microspheres can be easily collected by applying external magnetic field due to the magnetic property of core Fe3O4 particles. Compared to unmodified Fe3O4@TiO2 microspheres, the Fe3O4@TiO2@Au microspheres showed higher photocatalytic activity for 2, 4, 6-trichlorophenol (TCP). The photocatalytic efficiency of the Fe3O4@TiO2 microspheres was 28% after 40 min irradiation while, the efficiency of Fe3O4@TiO2@Au microspheres was 98% at the same condition. 相似文献
Fe3O4 coated glycine doped polypyrrole magnetic nanocomposite (Fe3O4@gly-PPy NC) was prepared via coating of suspended Fe3O4 nanoparticles with gly-PPy. FE-SEM and HR-TEM images indicated that Fe3O4 nanoparticles were encapsulated by precipitating gly-PPy moieties. Chromium(VI) adsorption followed a Langmuir isotherm with maximum capacity of 238–303 mg/g for a temperature range of 25–45 °C at pH 2. The adsorption process was governed by the ionic interaction and the reduction of Cr(VI) to Cr(III) by the PPy moiety. Results showed that NCs are effective adsorbents for the removal of Cr(VI) from wastewater and can be separated by external magnetic field from the reactor. 相似文献
Citric acid‐based sol‐gel method has been used to synthesize metal oxides widely. Iron‐based one‐dimensional nanostructured materials, including Fe2O3 nanotubes and Fe3O4 nanofibers, have been successfully prepared by directly annealing electrospun citric acid‐based precursor fibers under different atmospheres in this study. Thermo‐gravimetric and differential thermal analyses were carried out from room temperature to 800°C under air and argon atmosphere, respectively. The results reveal the formation mechanisms for Fe2O3 nanotube and Fe3O4 nanofiber. Fe2O3 tubular structures with average inner diameter about 500 nm and wall thickness about 20 nm were obtained. Fe3O4 nanoparticles were self‐assembled along the one dimensional orientation to form Fe3O4 nanofibers with average diameter around 500 nm. The reflection losses as a function of frequency for the samples with 23 and 33 wt% Fe3O4 nanofibers in paraffin were examined. The frequency dependence of reflection losses under various matching thicknesses (2, 3, 4, 6 and 8 mm) was simulated. The as‐fabricated Fe3O4 nanofibers can be believed to be promising candidates as highly effective microwave absorbers. 相似文献
In accordance with the World Cancer Report, cancer has become the leading cause of mortality worldwide, and various therapeutic strategies have been developed at the same time. In the present study, biocompatible magnetic nanoparticles were designed and synthesized as high-performance photothermal agents for near-infrared light mediated cancer therapy in vitro. Via a facile one-pot solvothermal method, well-defined PEGylated magnetic nanoparticles (PEG–Fe3O4) were prepared with cheap inhesion as a first step. Due to the successful coating of PEG molecules on the surface of PEG–Fe3O4, these nanoparticles exhibited excellent dispersibility and dissolvability in physiological condition. Cytotoxicity based on MTT assays indicated these nanoparticles revealed high biocompatibility and low toxicity towards both Hela cells and C6 cells. After near-infrared (NIR) laser irradiation, the viabilities of C6 cells were effectively suppressed when incubated with the NIR laser activated PEG–Fe3O4. In addition, detailed photothermal anti-cancer efficacy was evaluated via visual microscope images, demonstrating that our PEG–Fe3O4 were promising for photothermal therapy of cancer cells. 相似文献
Summary: Ultrasonic irradiation was employed to prepare polypyrrole (PPY)/Fe3O4 magnetic nanocomposite by chemical oxidative polymerization of pyrrole in the presence of Fe3O4 nanoparticles. This approach can solve the problem in the dispersion and stabilization of inorganic nanoparticles in polymer. The structure and properties of PPY/Fe3O4 nanocomposite were characterized by TEM, XPS, FT‐IR, TG, and XRD. PPY deposits on the surface of Fe3O4 nanoparticles while Fe3O4 nanoparticles are dispersed at the nanoscale by ultrasonic irradiation, which leads to the formation of polypyrrole‐encapsulated Fe3O4 composite particles. The doping level of PPY in PPY/Fe3O4 nanocomposite is higher than that of neat PPY. The composites possess good electrical and magnetic properties. With the increase in the Fe3O4 content, the magnetization increases and the conductivity first increases and then decreases. When the Fe3O4 content is 40 wt.‐%, the conductivity reaches a maximum value of 11.26 S · cm?1, about nine times higher than that of neat PPY, and the saturation magnetization is 23 emu · g?1. Also, the introduction of Fe3O4 nanoparticles enhances the thermal stability of PPY/Fe3O4 composite.
Conductivity of PPY/Fe3O4 composite at different Fe3O4 content. 相似文献
A modified method to prepare chitosan-poly(acrylic acid)(CS-PAA) polymer magnetic microspheres was reported in this paper. First, via self-assembly of positively charged CS and negatively charged Fe3O4 nanoparticles, magnetic CS cores with a large amount of Fe3O4 nanoparticles were successfully prepared. Subsequently, the AA monomers were polymerized on the magetic CS cores based on the reaction system of water-soluble polymer-monomer pairs. These polymer magnetic microspheres had a high Fe3O4 loading content, and showed unique pH-dependent behaviors on the size and zeta potential. From the magnetometer measurements data, the CS-PAA polymer magnetic microspheres also had superparamagnetic property as well as fast magnetic response. A continuous release of the entrapped ammonium glycyrrhizinate in such polymer magnetic microspheres occurred, which confirmed the potential applications of these microspheres for the targeted delivery of drugs. 相似文献
Different phosphates and phosphonates have shown excellent coating ability toward magnetic nanoparticles, improving their stability and biocompatibility which enables their biomedical application. The magnetic hyperthermia efficiency of phosphates (IDP and IHP) and phosphonates (MDP and HEDP) coated Fe3O4 magnetic nanoparticles (MNPs) were evaluated in an alternating magnetic field. For a deeper understanding of hyperthermia, the behavior of investigated MNPs in the non-alternating magnetic field was monitored by measuring the transparency of the sample. To investigate their theranostic potential coated Fe3O4-MNPs were radiolabeled with radionuclide 177Lu. Phosphate coated MNPs were radiolabeled in high radiolabeling yield (>?99%) while phosphonate coated MNPs reached maximum radiolabeling yield of 78%. Regardless lower radiolabeling yield both radiolabeled phosphonate MNPs may be further purified reaching radiochemical purity of more than 95%. In vitro stabile radiolabeled nanoparticles in saline and HSA were obtained. The high heating ability of phosphates and phosphonates coated MNPs as sine qua non for efficient in vivo hyperthermia treatment and satisfactory radiolabeling yield justifies their further research in order to develop new theranostic agents.
Hybrid nanocomposites consisting of uniform Fe3O4 nanoparticles and boron nitride (BN) nanospheres were synthesized via an ethanol-thermal reaction method. The spherical BN nanoparticles (BNNSs) with average diameter 150 nm have been uniformly coated with dense ultra-small Fe3O4 nanoparticles (with average diameter of 10 nm), forming novel Fe3O4@BNNS nanocomposites. Magnetic measurement by using vibrating sample magnetometer (VSM) indicates that the Fe3O4 coating is superparamagnetic, and the nanocomposites can be physically manipulated at a low magnetic field. Preliminary biocompatibility study has also been performed to evaluate the toxicity of the nanocomposites. The nanocomposites show cytocompatibility at low concentration and have little effect on cell viability of MCF-7, MCF-10 and Hela cell lines. The Fe3O4@BNNS nanocomposites may find a wide range of potential applications including water treatment, catalysts, carriers for boron neutron capture therapy and magnetic-targeted drug delivery. 相似文献
Luminomagnetic nanostructured Nd3+ doped fluorapatite (FAP) coated Fe3O4 nanoparticles were produced by hydrothermal method. X-ray diffraction analysis indicates that the prepared nanoparticles contain both FAP and Fe3O4 phases. Electron microscope analysis shows the formation of nanoparticles of Fe3O4 encased in rod shaped FAP nanoparticles of average length 40 nm. Magnetic measurements confirm the room temperature superparamagnetic nature of the nanoparticles with saturation magnetization value up to 7.8 emu/g. The prepared nanoparticles display strong near infrared (NIR) emission at 1060 nm under 800 nm excitation. Cell viability studies for 72 hour demonstrate the survival rate of over 84% with 500 μg/mL concentration indicating the good cytocompatibility of the prepared materials. The present Nd3+ doped FAP coated Fe3O4 nanostructure provides an excellent multifunctional platform for diagnostics and therapeutic applications. 相似文献
In the present work, Mg0.5Ni0.5Fe2O4 nanopowders were prepared by a sol-gel combustion method. The magnetic properties, heat generation ability in an AC magnetic field and cytotoxicity of the mixed ferrite nanopowders were investigated. The results showed that the powders have crystalline spinel structure with a particle size in the range of 20-90 nm. Maximum saturation magnetization (Ms) of 51 emu/g was obtained for the Mg0.5Ni0.5Fe2O4 nanoparticles calcined at 900°C. The results showed that, the coercivity (Hc) of the Mg0.5Ni0.5Fe2O4 initially increases up to 700°C and then decreases with increasing temperature, whereas the Ms of the samples continuously increases. The Mg0.5Ni0.5Fe2O4 sample exhibited a temperature increase up to 45°C during 10 minutes in the exposure of magnetic field of 200 Oe. By increasing the viscosity of ferrofluid, the heat generation ability of nanoparticles reduced up to 9% at magnetic field of 200 Oe. Cell compatibility of the ferrite powders was studied by MTT assay using MG63 cell line proliferation. MTT results showed that calcination temperature of the Mg0.5Ni0.5Fe2O4 nanoparticles significantly affects the cell compatibility. 相似文献