共查询到20条相似文献,搜索用时 62 毫秒
1.
Weijia Zhou Shide Zhong Hongshi Zhao Shunpu Yan 《Journal of magnetism and magnetic materials》2009,321(8):1025-1028
Magnetic Fe3O4 materials with mesoporous structure are synthesized by co-precipitation method using yeast cells as a template. The X-ray diffraction (XRD) pattern indicates that the as-synthesized mesoporous hybrid Fe3O4 is well crystallized. The Barrett-Joyner-Halenda (BJH) models reveal the existence of mesostructure in the dried sample which has a specific surface area of 96.31 m2/g and a pore size distribution of 8-14 nm. Transmission electron microscopy (TEM) measurements confirm the wormhole-like structure of the resulting samples. The composition and chemical bonds of the Fe3O4/cells composites are studied by Fourier transform infrared (FT-IR) spectroscopy. Preliminary magnetic properties of the mesoporous hybrid Fe3O4 are characterized by a vibrating sample magnetometer (VSM). The magnetic Fe3O4/cells composites with mesoporous structure have potential applications in biomedical areas, such as drug delivery. 相似文献
2.
Yanling Zhang Qinghong Zhang Yaogang Li Hongzhi Wang 《Journal of magnetism and magnetic materials》2010,322(14):2006-2009
A magnetic multi-walled carbon nanotubes-based (MWCNTs-based) composite, MWCNTs/Ni0.5Zn0.5Fe2O4, was synthesized via a facile solvothermal approach. The composites were characterized by X-ray diffraction analysis, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and vibrating sample magnetometry. The results confirmed that MWCNTs and Ni0.5Zn0.5Fe2O4 coexisted in the composites. The TEM and HRTEM results showed a thick layer of Ni0.5Zn0.5Fe2O4 was intimately connected to the surface of MWCNTs. The saturation magnetization value of the composites was 45.8 emu/g. Furthermore, the probable synthesis mechanism of the magnetic composites was also investigated based on the experimental results. 相似文献
3.
Core-shell-structured LiNi0.5La0.08Fe1.92O4-polyaniline (PANI) nanocomposites with magnetic behavior were synthesized by in situ polymerization of aniline in the presence of LiNi0.5La0.08Fe1.92O4 nanoparticles. The structure, morphology and magnetic properties of samples were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV-vis absorption, transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) technique. The results of spectroanalysis indicated that there was interaction between PANI chains and ferrite particles. TEM study showed that LiNi0.5La0.08Fe1.92O4-PANI nanocomposites presented a core-shell structure with a magnetic core of 30-50 nm diameter and an amorphous shell of 10-20 nm thickness. The nanocomposites under applied magnetic field exhibited the hysteresis loops of the ferromagnetic nature. The saturation magnetization and coercivity of nanocomposites decreased with decreasing content of LiNi0.5La0.08Fe1.92O4. The polymerization mechanism and bonding interaction in the nanocomposites have been discussed. 相似文献
4.
A novel organic/inorganic composite based on LiNi–ferrospinel with poly(methyl methacrylate) (PMMA) and polyaniline (PANI), PANI/PMMA/LiNi0.5Fe2O4 composite, was synthesized via a facile in-situ polymerization process. The structures of the resulting samples were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, and atomic force microscopy. The optical and thermal properties of the PANI/PMMA/LiNi0.5Fe2O4 composite were studied by fluorescent spectroscopy and thermogravimetry analysis. It was indicated that the existence of LiNi0.5Fe2O4 (LFNO) in the PANI/PMMA/LFNO composite resulted in changes in the fluorescence spectra. The as-obtained composite may have potential for electrical and electromagnetic applications in antistatic materials, electromagnetic shields, radar absorbers, and so forth. 相似文献
5.
Lanathum (La)‐doped Fe3O4 magnetic nanoparticles were prepared in aqueous solution at room temperature, then La‐doped Fe3O4‐polyaniline (PANI) nanocomposites containing a dispersion of La‐doped Fe3O4 nanoparticles were synthesized via in‐situ polymerization of aniline monomer. The structure and properties of the synthesized samples were characterized with X‐ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FTIR), thermogravimetric analysis (TGA), inductively coupled plasma atomic emission spectrometry (ICPAES), and a vibrating sample magnetometer (VSM). The resulting particles of La‐doped Fe3O4 and La‐doped Fe3O4‐PANI were almost spherical with diameters ranging from 15 to 25 nm and 25 to 85 nm, respectively. The La‐doped Fe3O4‐PANI composite presented core‐shell structures; polyaniline covered the La‐doped Fe3O4 completely. The specific saturation magnetization of La‐doped Fe3O4‐PANI depended on the starting material of La‐doped Fe3O4. It increased with increasing amounts of La and Fe3O4 content. 相似文献
6.
After hollow microspheres (HM) were surface modified, a layer of electromagnetic polyaniline/Fe3O4 composite (PAN/Fe3O4) was successfully grafted onto the surface of the self-assembled monolayer coated HM, resulting in HM/PAN/Fe3O4 composites. In this approach, γ-aminopropyltriethoxy silane was adopted to form a well-coating monolayer with amino groups for the graft polymerization of aniline, which played an important role in fabricating the core-shell structure. FeCl3 was used as the oxidant not only for aniline to form PAN, but also for FeCl2 to prepare the magnets. The structure, morphologies, and magnetic properties of the as-prepared samples were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and vibrating sample magnetometer. The results indicated that the HM/PAN/Fe3O4 composites possess low density (ρ < 1.0 g/cm3), controllable morphology, and good magnetic properties at room temperature (saturation magnetization Ms = 8.32 emu g−1 and coercive force Hc ≈ 0). 相似文献
7.
Polyaniline/BaFe12O19 (PANI/Ba ferrite) composites were synthesized by in situ polymerization at different aniline/Ba ferrite weight ratios (Ani/Ba ferrite=1/2, 1/1 and 2/1) and introduced into epoxy resin to be microwave absorber. The spectroscopic characterizations of the formation processes of PANI/Ba ferrite composites were studied using Fourier transform infrared, ultraviolet-visible spectrophotometer, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and electron spin resonance. Microwave-absorbing properties were investigated by measuring complex permittivity, complex permeability and reflection loss in the 2-18 and 18-40 GHz microwave frequency range using the free space method. The results showed that a wider absorption frequency range could be obtained by adding different polyaniline contents in Ba ferrite. 相似文献
8.
J.C. Aphesteguy Abel Damiani Dalmas DiGiovanni S.E. Jacobo 《Physica B: Condensed Matter》2009,404(18):2713-2716
NiZn- and NiCuZn-ferrite nanoparticles (50–70 nm) with the chemical formula Ni0.5 Zn0.5Fe2O4 (NiZn) and Ni0.35Cu0.15Zn0.5Fe2O4 (NiCuZn) were synthesized by a combustion synthesis method. The nanocrystallite of these materials was characterized by structural and magnetic methods. Saturation magnetization increases from 83 emu/g (NiZn) to 91 emu/g (NiCuZn). Magnetic permeability and dielectric permittivity were measured on sintered samples (pellets and toroids) in the frequency range of 1 MHz–1.8 GHz. Reflection losses (RL) for both samples were calculated from complex permeability and permittivity. Cu substitution in NiZn-ferrite enhances permeability and RL.In order to explore microwave-absorbing properties in X-band, magnetic nanoparticles were mixed with an epoxy resin to be converted into a microwave-absorbing composite and microwave behaviors of both materials were studied using a microwave vector network analyzer from 7.5 to 13.5 GHz. Cu substitution diminishes absorption intensity in the range 11.5–12.5 GHz. 相似文献
9.
Nano-magnetic Fe3O4 particles coated with silica are synthesized. The study of structural and magnetic properties was carried out using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and vibrating sample magnetometer (VSM) techniques. The VSM results show that these kinds of composite particles exhibit superparamagnetic behavior with zero coercivity and remanence. The magnetic spheroid alumina carriers containing these magnetic composite particles were prepared by an internal gelation process. The SiO2 coatings prevent the reaction between Fe3O4 and Al2O3 during the sintering process and maintain the superparamagnetic behavior of the catalyst carriers. 相似文献
10.
Cui-Ping Wang Chuan-Hao Li Hong Bi Ju-Chuan Li Hui Zhang An-Jian Xie Yu-Hua Shen 《Journal of nanoparticle research》2014,16(3):1-11
For the first time, the novel one-dimensional uniform polyaniline (PANI)/Ni0.5Zn0.5Fe2O4 (NZFO) hybrid nanorods were synthesized by an in situ polymerization approach with the assistance of ultrasound and magnetic field. Owing to the unique shape, structure, and chemical composition, the as-synthesized hybrid nanorods with different PANI/NZFO mass ratios possess adjustable magnetic properties, high-saturated magnetization, and coercivity. In addition, these hybrid nanorods present stronger reflection loss and a wider absorption band than pure NZFO. Especially, the hybrid nanorods containing 59 wt% NZFO exhibit excellent microwave absorption properties, with a maximum reflection loss (R L) of ?27.5 dB observed at 6.2 GHz. And the widest absorption band (R L ≤ ?10 dB) is 8.1 GHz, corresponding to a matching thin thickness of 2 mm. It is superior to the previously reported value of PANI/ferrite. Therefore, these PANI/NZFO hybrid nanorods may be candidates for lightweight, low-cost, broadband, and highly efficient microwave-absorbing materials. 相似文献
11.
Magnetic nanocomposites can be controlled and tailored to provide the desired mechanical, physical, chemical, and biomedical properties depending on the final applications. The coating of ferrite nanoparticles with polymers affords the possibility of minimizing agglomeration in large-scale commercial synthesis of nanocomposite materials. The process of coating not only provides effective encapsulation of individual nanoparticles, but also controls the growth in size, thus, yielding a better overall size distribution. In this paper, in-situ polymerization of aniline was carried out in different concentration of the ferrofluid with the aim to obtain agglomerate free nanocomposites. The role of the ferrite concentration was investigated by the spectral, morphological, conductivity, and magnetic properties of Fe3O4/polyaniline (PANI) nanocomposites. XRD revealed the presence of spinel phase of Fe3O4 and the particle size was calculated to be 14.3 nm. Spectral analysis confirmed the formation of PANI encapsulated Fe3O4 nanocomposite. Conductivity of the nanocomposites was found to be in the range of 0.001–0.003 S/cm. Higher saturation magnetization of 3.2 emu/g was observed at 300 K, revealing a super paramagnetic behavior of this nanocomposite. 相似文献
12.
Junji WeiYingqing Zhan Xulin YangFanbin Meng Zhen MaRui Zhao Jiachun ZhongJiandong Zhang Xiaobo Liu 《Journal of magnetism and magnetic materials》2011,323(24):3210-3216
Novel organometal/Fe3O4 hybrid microspheres were prepared from bisphthalonitrile-benzoxine resin containing ferrocene (FPNBZ) and FeCl3·6H2O via a one-step solvent-thermal method. The phase structure, composition and morphology of as-prepared hybrid microspheres were characterized by X-ray powder diffraction, Fourier transform infrared spectrophotometer and scanning electron microscopy. The results revealed that crystallinity, dispersity and size of hybrid microspheres can be controlled by altering the reaction parameters. Density measurement showed that the density is decreased with increasing FPNBZ concentration in the hybrid materials. Electromagnetic properties of the FPNBZ/Fe3O4 hybrid microspheres were measured at 2-18 GHz. The electromagnetic measurement indicated that the resonance peaks of complex permittivity, complex permeability, dielectric loss and magnetic loss were shifted to the high frequencies, with the increasing amount of FPNBZ. The as-prepared hybrid materials are believed to have broad applications both in microwave absorption materials in a wide frequency range and in biomedical fields. 相似文献
13.
Reza Shams Alam Masoud Kavosh TehraniMahmood Moradi Ehsaneh HosseinpourAli Sharbati 《Journal of magnetism and magnetic materials》2011,323(8):1040-1043
The effect of Mg2+, Co2+and Ti4+ substitution on microwave absorption has been studied for BaMg0.5Co0.5Ti1.0Fe10O19 ferrite-acrylic resin composite in frequency range from 13 to 20 GHz. X-ray diffraction (XRD), scanning electron microscopy (SEM), vector network analysis and vibrating sample magnetometry (VSM) were employed to analyze structure, electromagnetic and microwave absorption properties of prepared ferrite. The obtained results of reflectivity demonstrate that by varying matching thickness along with weight percentage of ferrite to acrylic resin, the bandwidth coupled with reflection loss values of prepared composites can be easily tuned. Based on microwave measurement on reflectivity, it is found that BaMg0.5Co0.5Ti1.0Fe10O19 is a good candidate for wideband electromagnetic compatibility and other practical applications at high frequency. 相似文献
14.
Haiqing XiaBin Cui Junhong ZhouLulu Zhang Ji ZhangXiaohui Guo Huilin Guo 《Applied Surface Science》2011,257(22):9397-9402
We synthesized Fe3O4@C@Ag nanocomposites through a combination of solvothermal, hydrothermal, and chemical redox reactions. Characterization of the resulting samples by X-ray diffraction, Fourier-transform infrared spectroscopy, field-emission scanning and transmission electron microscopy, and magnetic measurement is reported. Compared to Fe3O4@Ag nanocomposites, the Fe3O4@C@Ag nanocomposites showed enhanced antibacterial activity. The Fe3O4@C@Ag nanocomposites were able to almost entirely prevent growth of Escherichia coli when the concentration of Ag nanoparticles was 10 μg/mL. Antibacterial activity of the Fe3O4@C@Ag nanocomposites was maintained for more than 40 h at 37 °C. The intermediate carbon layer not only protects magnetic core, but also improves the dispersion and antibacterial activity of the silver nanoparticles. The magnetic core can be used to control the specific location of the antibacterial agent (via external magnetic field) and to recycle the residual silver nanoparticles. The Fe3O4@C@Ag nanocomposites will have potential uses in many fields as catalysts, absorbents, and bifunctional magnetic-optical materials. 相似文献
15.
A. Azizi S.K. Sadrnezhaad A. Hasani 《Journal of magnetism and magnetic materials》2010,322(21):3551-1520
Properties of FeCo nanocrystalline intermetallic powders prepared by salt-matrix hydrogen reduction of a milled Fe2O3-Co3O4 mixture were investigated. The product of 72 ks ball-milling at 350 rpm was CoFe2O4 nanopowder. Reduction of this powder for 3.6 ks by hydrogen at 750 °C resulted in the formation of Fe0.67Co0.33 stoichiometric compound. Scanning electron microscopy, electron dispersive spectrometry, X-ray diffraction and vibrating sample magnetometry were used to characterize the nanopowder. Using a salt-matrix (NaCl as a dispersion medium) resulted in the decrease of the reduction temperature and improvement of the morphology and magnetic properties of the nanopowder. Dispersion of the ball-milled product in Hexan resulted in further improvements of the magnetic properties. 相似文献
16.
We described a method for synthesizing hollow silica/magnetic composite spheres using sulfonic acid functionalized hollow silica spheres (SAFHSS) as templates. The Fe3O4 nanoparticles were deposited on or imbedded in the hollow silica shell by a precipitation reaction. The morphologies, composition and properties of the hollow composite spheres were characterized by transmission electron microscopy, Fourier transform infrared analysis, X-ray diffraction measurement and vibrating-sample magnetometry measurement. The results indicated crystal sizes and amount of the Fe3O4 nanoparticles on the SAFHSS. The magnetic properties of the hollow composite spheres were controlled by adjusting the proportion between Fe2+ and Fe3+ and iron ion total concentration. When appropriate loading species were added into the system, superparamagnetite hollow composite spheres were obtained. The method also could be applicable to prepare other superparamagnetite hollow silica/ferrite composite spheres. 相似文献
17.
Yuqing Li Ying Huang Shuhua QiLei Niu Yinling ZhangYanfei Wu 《Applied Surface Science》2012,258(8):3659-3666
Strontium ferrite particles were firstly prepared by sol-gel method and self-propagating synthesis, and then the polyaniline/strontium ferrite/multiwalled carbon nanotubes composites were synthesized through in situ polymerization approach. Structure, morphology and properties of the composite were characterized by various instruments. XRD analysis shows that the output of PANI increases with the increase of the content of MWCNTs, due to the large surface area of MWCNTs. Because of the coating of PANI, the outer diameter of MWCNTs increases from 10 nm to 20-40 nm. The electrical conductivity of the composites increases with the amount increase of MWCNTs and reaches 7.2196 S/cm in the presence of 2 g MWCNTs. The coercive force of the composites prepared with 2 g MWCNTs is 7457.17 Oe, which is much bigger than that of SrFe12O19 particles 6145.6 Oe, however, both the saturation magnetization and the remanent magnetization of the composite become much smaller than those of SrFe12O19 particles. The electromagnetic properties of the composite are excellent in the frequency range of 2-18 GHz, which mainly depend on the dielectric loss in the range of 2-9 GHz, and mainly on the magnetic loss in the range of 9-18 GHz. 相似文献
18.
C. C. Zhang X. Li Y. Yang C. Wang 《Applied Physics A: Materials Science & Processing》2009,97(2):281-285
Ultra-low dielectric permittivity poly (methyl methacrylate)/Fe3O4 composite fiber membranes have been successfully prepared using electrospinning. The composite membranes were characterized
by SEM (scanning electron microscopy), TEM (transmission electron microscopy), FT-IR (Fourier transform infrared), XRD (X-ray
diffraction) and a radio frequency (RF) impedance/capacitance material analyzer. The magnetic measurement showed that the
composite membranes displayed the super-paramagnetic property. The results showed that the dielectric permittivity of the
composite fiber membranes was decreasing with increasing Fe3O4 nanoparticle content. 相似文献
19.
The use of carbon shells offers many advantages in surface coating or surface modification due to their surface with activated
carboxyl and carbonyl groups. In this study, the Fe3O4@C@YVO4:Eu3+ composites were prepared through a simple sol–gel process. Reactive carbon interlayer was introduced as a key component,
which separates lanthanide-based luminescent component from the magnetite, more importantly, it effectively prevent oxidation
of the Fe3O4 core during the whole preparation process. The morphology, structure, magnetic, and luminescent properties of the composites
were characterized by transmission electron microscopy (TEM), high-resolution TEM, X-ray diffraction, X-ray photoelectron
spectra, VSM, and photoluminescent spectrophotometer. As a result, the Fe3O4@C/YVO4:Eu3+ composites with well-crystallized and core–shell structure were prepared and the YVO4:Eu3+ luminescent layer decorating the Fe3O4@C core–shell microspheres are about 10 nm. In addition, the Fe3O4@C@YVO4:Eu3+ composites have the excellent magnetic and luminescent properties, which allow them great potential for bioapplications such
as magnetic bioseparation, magnetic resonance imaging, and drug/gene delivery. 相似文献
20.
Milan Timko Anezka Dzarova Andrzej Skumiel Tomasz Hornowski Vlasta Zavisova Adriana Sprincova Peter Kopcansky 《Journal of magnetism and magnetic materials》2009,321(10):1521-1524
A suspension of bacterial magnetosomes was investigated with respect to structural and magnetic properties and hyperthermic measurements. The mean particle diameter of about 35 nm was confirmed by transmission electron microscopy (TEM), X-ray and magnetic analysis. The X-ray powder diffraction peaks of magnetosomes fit very well with standard Fe3O4 reflections. The found value for specific absorption rate (SAR) of 171 W/g at 5 kA/m and 750 kHz means that magnetosomes may be considered as good materials for the biomedical applications in hyperthermia treatments. Moreover, they have biocompatible phospholipid membrane. 相似文献