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1.
Nickel ferrite nanoparticles were successfully synthesized via a co-precipitation approach, and then polyrhodanine/nickel ferrite nanocomposite (PRh/NiFe 2O 4) as an antimicrobial agent was fabricated by a chemical polymerization method. The synthesized NiFe 2O 4 nanoparticles and PRh/NiFe 2O 4 nanocomposite were chemically, magnetically and morphologically characterized using FTIR, FESEM, DLS, VSM and XRD techniques. The FESEM analysis showed that the NiFe 2O 4 nanoparticles had a polygon structure with an average diameter of 50 nm. According to disc diffusion as well as MIC and MBC tests, the PRh/NiFe 2O 4 nanocomposite had better antibacterial effects on killing Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli in comparison with the NiFe 2O 4 nanoparticles. 相似文献
2.
We report an adjustable magnetic resonance frequency from 1.45 to 2.54 GHz for NiFe 2O 4 nanoparticles which were prepared by a sol–gel process. X-ray diffraction and scanning electron microscopy results indicate that the samples are polycrystalline nanoparticles, and the size of the particles increases obviously with the thermal treatment temperature. The consequence of the surface composition suggests that the oxygen defects are present in the nanoparticle surface, and this surface magnetic state can show a strong surface anisotropy. With decreasing size of the particle, the surface magnetic effect is predominant, resulting in an increase of resonance frequency for NiFe 2O 4 nanoparticles. This finding provides a new route for NiFe 2O 4 materials that can be used in the gigahertz range. 相似文献
3.
Nanocrystalline NiFe 2O 4 was synthesized by sol-gel route using various surfactants such as PVP, EDTA and CTAB. The effect of different surfactants on structure, magnetic and dielectric properties of the NiFe 2O 4 nanoparticles (NPs) were investigated. The prepared samples were inspected by XRD, HRSEM, and TEM. Powder XRD studies confirmed the realization of single crystalline cubic structure of the NiFe 2O 4 nanoferrites. The addition of surfactants significantly modified the crystallite size of the final products. Dielectric features of NiFe 2O 4 NPs were slightly modified with different surfactants. The magnetic results revealed an enormous decrease in coercivity and a moderate reduction in the saturation magnetization when EDTA and CTAB were used as compared to PVP. The present results declare that the adding of various surfactants in the sample preparation controls the size of NiFe 2O 4 NPs and thus noticeably influences the magnetic parameters. 相似文献
4.
We report a facile non-templated hydrothermal synthesis method for the production of nickel ferrite (NiFe 2O 4)/carbon nanotube nanocomposite comprised of oxidized multi-walled carbon nanotube (o-MWCNT) uniformly coated with nanoparticles of NiFe 2O 4 (1–5 nm). The carboxylate groups of the o-MWCNT coordinate the nanoparticles strongly at its surface, and the size of the NiFe 2O 4 particles can be controlled by the subtle variation of reaction time and the quantity of o-MWCNT used. We believe that this method can be extended to allow the uniform coating of different spinel-type materials onto o-MWCNT and other nanocarbon materials. 相似文献
5.
The effects of three types of salt including NaF, KCl, and NaCl on the properties of NiFe 2O 4 nanoparticles using salt-assisted solution combustion synthesis (SSCS) have been investigated. The synthesized powders were evaluated by SEM, TEM, FTIR, XRD, and VSM analysis. Also, the specific surface area (SSA), as well as size distribution and volume of the porosities of NiFe 2O 4 powders were determined by the BET apparatus. The visual observations showed that the intensity and time of combustion synthesis of nanoparticles have been severely influenced by the type of salt. The highest crystallinity was observed in the synthesized powder using NaCl. The SSA has also been correlated completely to the type of salt. The quantities of SSA was achieved about 91.62, 64.88, and 47.22 m 2g -1 for the powders synthesized by KCl, NaCl, and NaF respectively. Although the magnetic hysteresis loops showed the soft ferromagnetic behavior of the NiFe 2O 4 nanoparticles in all conditions, KCl salt could produce the particles with the least coercivity and remanent magnetization. Based on the present study, the salt type is a key parameter in the SSCS process for the preparation of spinel ferrites. Thermodynamic evaluation also showed that the melting point and heat capacity are important parameters for the proper selection of the salt. 相似文献
6.
Polypyrrole/NiFe 2O 4 (PPy/NiFe 2O 4) composites were prepared by ultrasonic oxidative polymerization in the presence of NiFe 2O 4 nanoparticles (NPs). The nanostructure of PPy/NiFe 2O 4 was confirmed by the X‐ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and vibrating sample magnetometer (VSM) examinations. The adsorption of Cr(VI) onto the PPy/NiFe 2O 4 composite was lowly pH dependent and the adsorption kinetics followed the Pseudo‐second‐order model. The Langmuir isothermal model well described the adsorption isotherm data and the maximum adsorption capacity increased with the increase of temperature. The maximum adsorption capacity of the PPy/NiFe 2O 4 for Cr(VI) ions was up to 50 mg/g at pH 2.0. The excellent adsorption characteristic of PPy/NiFe 2O 4 composite will render it a highly efficient and economically viable adsorbent for Cr(VI) ions removal. POLYM. COMPOS., 38:2779–2787, 2017. © 2015 Society of Plastics Engineers 相似文献
7.
A straightforward strategy is designed for the fabrication of a magnetically separable NiFe 2O 4‐graphene photocatalyst with different graphene content. It is very interesting that the combination of NiFe 2O 4 nanoparticles with graphene sheets results in a dramatic conversion of the inert NiFe 2O 4 into a highly active catalyst for the degradation of methylene blue (MB) under visible light irradiation. The significant enhancement in photoactivity under visible light irradiation can be ascribed to the reduction of GO, because the photogenerated electrons of NiFe 2O 4 can transfer easily from the conduction band to the reduced GO, effectively preventing a direct recombination of electrons and holes. The results of the kinetic study indicated that the rate‐determining stage is the adsorption process of MB molecules. NiFe 2O 4 nanoparticles themselves have a strong magnetic property, which can be used for magnetic separation in a suspension system, and, therefore, the introduction of additional magnetic supports is no longer necessary. © 2011 American Institute of Chemical Engineers AIChE J, 2012 相似文献
8.
NiFe 2O 4-based ceramic inert anodes for aluminum electrolysis doped with various TiN nanoparticles were prepared by a two-step cold-pressing sintering process to investigate how TiN affected the sintering behavior and properties of the composites. The differential scanning calorimetry-thermogravimetry (DSC-TG), X-ray diffraction (XRD), and microstructure analysis results indicated that the Ti and N were evenly distributed in the NiFe 2O 4 matrix to form a solid solution. The maximum linear shrinkage and linear shrinkage rate were enhanced with the increase of TiN nanoparticles contents, and the sintering activation energy of initial stage was lowered from 382.63 to 279.58 kJ mol −1 with the TiN nanoparticles additive range from 0 to 9 wt%. When the content of TiN nanoparticles was 7 wt%, the relative density, bending strength, and elastic modulus reached their maximum values of 97.24%, 73.88 MPa, and 3.77 GPa, respectively, whereas the minimum static corrosion rate of NiFe 2O 4-based ceramic of 0.00114 g cm −2 h −1 was obtained, mainly attributed to the relatively dense and stable microstructure. The electrical conductivity of NiFe 2O 4-based ceramics presented a clear ascending trend with increasing TiN nanoparticles content and elevated temperature, attributed to the increased concentration and migration rate of carrier. 相似文献
9.
New electromagnetic nanocomposites were prepared from polyaniline (PANI)/oxidized single‐walled carbon nanotubes (OxSWCNTs)/NiFe 2O 4 by in situ polymerization of aniline using hexanoic acid as a soft template. OxSWCNT and NiFe 2O 4 were prepared first so as to be used in the formulation of PANI composites. Transmission electron microscope (TEM) results revealed the formation of PANI nanoparticles of 60 nm diameter, OxSWCNT of 24 nm, and NiFe 2O 4 of 54 nm. Also, TEM image of the ternary composite indicated agglomerative coating of PANI appearing as a gray shells and black core of NiFe 2O 4 with widening the diameter of OxSWCNT to be around 66 nm. Dc conductivity was measured as a function of temperature. Magnetic susceptibility was measured as a function of temperature and magnetic field intensity. All samples revealed NiFe 2O 4‐dependent ferromagnetism. The activation energies for dc conductivity suggest that the conductivity is owing to hopping conduction mechanism. A synergistic effect between NiFe 2O 4 and PANI/OxSWCNT is observed. POLYM. COMPOS.,, 2012. © 2012 Society of Plastics Engineers 相似文献
10.
Well‐crystallized Cobalt ferrite nanoparticles with mean size of 20 nm and high saturation magnetization (82.9 emu/g) were synthesized at a low temperature (≤100°C) by microwave‐assisted solid–liquid reaction ball‐milling technique without subsequent calcination. CoC 2O 4·4H 2O and Fe powder were used as raw materials and stainless steel or pure iron milling balls with diameter of 1.5 mm were used. As a contrast, solid–liquid reaction ball milling without microwave assistance was also investigated. The results showed that this is a simple, environmentally friendly, and energy‐saving technique for ferrite nanocrystal synthesis. 相似文献
11.
In this paper, the core–shell structured NiFe 2O 4@TiO 2 nanoparticles and nanochains as photocatalysts were successfully prepared through hydrothermal and hydrolysis method. The as-prepared core–shell structure was composed of a magnetic NiFe 2O 4 core and photocatalytic titanium oxide coating shell. SEM and TEM images characterized the morphology of NiFe 2O 4@TiO 2 nanoparticles. Moreover, the results of XRD patterns proved that the TiO 2 coating shell consisted of anatase. The VSM measurements showed that the saturation magnetization values of NiFe 2O 4 and NiFe 2O 4@TiO 2 nanoparticles was 65 and 53 emu/g, respectively. The photocatalyst of NiFe 2O 4@TiO 2 nanoparticles exhibited the outstanding recyclable performance for RhB. And, the photo_degradation ration of maintained 69 % after the photocatalyst experienced ten photocatalysis experiments, which is better than that of Fe 3O 4@TiO 2 photocatalysts. 相似文献
12.
Silica coated NiFe 2O 4 NPs has been synthesized. It has been characterized by XRD, TEM, SEM-EDX and FT-IR. The catalytic activity of the Silica coated NiFe 2O 4 NPs has been tested for the S-arylation reaction in water with high yield. In this reaction water was used as the green solvent. The effects of solvents, reaction time and catalyst amount for the reaction was reported. This catalyst showed excellent catalytic activity and recyclability. The Silica coated NiFe 2O 4 NPs catalyst could be easily recovered by filtration and reused more than five times without appreciable loss of its initial activity. 相似文献
13.
Narrow size distribution nickel ferrite nanoparticles with average particle size of around 6 nm has been synthesized via rapid thermo-decomposition method in the presence of oleylamine in solution which acted as neutralizing, stabilizing and reducing agent OAm coated NiFe 2O 4 NPs. X-ray powder diffraction (XRD), Fourier Transform Infrared Spectra (FT-IR), Thermal Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM), Vibrating Simple Magnetometer (VSM) and also Mössbauer Spectroscopy were used for structural, morphological, spectroscopic and magnetic characterization of the product. The XRD analysis revealed the formation of single phase nickel ferrite with Fd-3m space group. Both FT-IR and TGA analyses confirmed the formation of desired nanocomposite. FT-IR analysis also showed characteristic IR absorption bands of the spinel nickel ferrite phase and oleylamine. TEM and SEM analysis showed that product have almost spherical structural morphology. TEM images showed that NiFe 2O 4 nanoparticles have narrow size distribution and Energy Dispersive X-ray (EDX) analysis confirmed the presence of metal ions in the required stoichiometric ratio. Superparamagnetic property of the product was confirmed by VSM. From 57Fe Mössbauer spectroscopy data, the variation in line width, isomer shift, quadrupole splitting and hyperfine magnetic field values have been determined. The Mössbauer spectra for OAm coated NiFe 2O 4 NPs. is consisting of one paramagnetic central doublets and one magnetic Zeeman sextet. Finally, the synthetic procedure can be extended to the preparation of high quality metal or alloy nanoparticles. 相似文献
14.
The nanocrystalline nickel ferrite (NiFe 2O 4) was synthesized by reactive milling starting from equimolar mixture of oxides. The iron contamination during milling leads to a solid state reaction between Fe and NiFe 2O 4 spinel. This reaction starts for a milling time longer than 30 h. A mixed nickel–iron ferrite (Ni 1?γFe 2+γO 4) and elemental Ni are obtained. The evolution of the nickel–iron mixed ferrite during milling and its properties were investigated using X‐ray diffraction, Fourier Transform Infrared Spectroscopy (FTIR), Laser Particles Size Analyzer and magnetic measurements. Annealing treatment (350°C/4 h in vacuum) is favorable to the reaction between phases. Replacement of Ni 2+ cations by iron cations provided by contamination leads to the increase of lattice parameter value of the spinel structure. The magnetization of the nickel–iron mixed ferrite newly formed is larger than the nickel ferrite magnetization (13.6 μ B/f.u. and 6.22 μ B/f.u., respectively), due to the magnetic moment of Fe 2+ cation which is double as compared to the Ni 2+ cation. Magnetization of the milled samples decreases during milling due to the structural changes induced by milling in the nickel–iron mixed ferrite. The annealing induces a reordering of the cations which leads to a larger magnetization. 相似文献
15.
High‐energy ball milling using comilling in a solid state by low‐temperature mechanical alloying to prepare nickel‐ferrite (NiFe 2O 4) nanopowders and ultrafine poly(methyl methacrylate) (PMMA), dispersing nanoparticles in a polymer matrix, and a uniaxial high‐velocity cold compaction process using a cylindrical, hardened steel die and a new technique with relaxation assists have been studied. The focus has been on the particle size distributions of the nanocomposite powder during the milling and on the surface morphology of the nanocomposite‐compacted materials after compaction with and without relaxation assists. Experimental results for different milling systems are presented showing the effects of milling time and material ratio. It was found that a longer mixing time give a higher degree of dispersion of the nanopowder on the PMMA particle surfaces. Furthermore, with increasing content of NiFe 2O 4 nanopowder, the reduction of the particle size was more effective. Different postcompacting profiles, i.e. different energy distributions between the upper and lower parts of the compacted powder bed, lead to different movements of the various particles and particle layers. Uniformity, homogeneity, and densification on the surfaces in the compacted powder are influenced by the postcompacting magnitude and direction. It was found that the relaxation assist device leads to an improvement in the polymer powder compaction process by reducing the expansion of the compacted volume and by reducing the different opposite velocities, giving the compacted composite bed a more homogeneous opposite velocity during the decompacting stage and reducing the delay time between the successive pressure waves. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers 相似文献
16.
Novel polysulfone (PSU)/NiFe 2O 4 nanocomposites with good magneto‐dielectric properties were prepared in a simple and cost‐effective manner. Nickel ferrite nanoparticles exhibit a cubic spinel phase without any impurity phases according to X‐ray diffraction characterization. Transmission electron microscopy images of the nanoparticles showed a tetragonal particle shape with average particle size of 17–30 nm. The thermal stability of PSU proved to remain unaffected by nanoparticle concentration in the composite material. The emission spectra of the PSU/NiFe 2O 4 nanocomposites present a broad emission band located at 370 nm due to free exciton recombination. The composites exhibit hysteresis loops of a ferrimagnetic nature and good dielectric properties. Coercivity value measured at room temperature is 20.64 and 24.98 Oe and the squareness ( Mr/ Ms) is 0.290 and 0.225 for both polymer composite samples (4 and 24 vol% Ni ferrite). The formalism of the dielectric loss has been used to estimate the dipolar relaxations expressed by γ‐ and β‐relaxation processes. The presence of Ni ferrite nanoparticles in the PSU matrix increases the activation energy of secondary relaxations, which means a reduction of the molecular mobility in the nanocomposites as compared to PSU. © 2018 Society of Chemical Industry 相似文献
17.
Three different spinel metal oxide catalytic systems including NiFe 2O 4, CuFe 2O 4 and CoFe 2O 4 were synthesized using co-precipitation technique and their catalytic activities were compared to each other in α-arylation of oxindole derivatives under the optimized reaction conditions. Both nickel ferrite and copper ferrite magnetic nanoparticles show approximately the same behavior in these reactions but cobalt ferrite ones indicate slightly different properties and were not as good as the other two catalysts. These superparamagnetic catalysts allowed that α-arylation of different types of oxindoles will occur in high yields under mild conditions and at very short times. 相似文献
18.
Abstract NiFe 2O 4 nanoparticles stabilized by porous silica shells (NiFe 2O 4@SiO 2) were prepared using a one-pot synthesis and characterized for their physical and chemical stability in severe environments,
representative of those encountered in industrial catalytic reactors. The SiO 2 shell is porous, allowing transport of gases to and from the metal core. The shell also stabilizes NiFe 2O 4 at the nanoparticle surface: NiFe 2O 4@SiO 2 annealed at temperatures through 973 K displays evidence of surface Ni, as verified by H 2 TPD analyses. At 1,173 K, hematite forms at the surface of the metallic cores of the NiFe 2O 4@SiO 2 nanoparticles and surface Ni is no longer observed. Without the silica shell, however, even mild reduction (at 773 K) can
draw Fe to the surface and eliminate surface Ni sites. 相似文献
19.
Two series samples of Iron Oxide nanoparticles doped with nickel and cobalt with different doping values (x?=?0.01; 0.03; 0.05 and 0.07), were successfully synthesized by using sol–gel method, and then they were characterized by X-ray diffraction, scanning electron and vibrating sample magnetometer (VSM). X-ray diffraction analysis of two series samples showed the formation α-Fe2O3 nanoparticles, accompanied by two phases iron spinels, CoFe2O4 and NiFe2O4. In addition, the variations in grain size were observed for both two series. The observation by scanning electron microscopy reveals a change in the morphology of the grains of all the samples doped, which confirm the cobalt and nickel effect on the morphology of iron oxide nanoparticles. Magnetic measurements which were measured by VSM showed significant magnetic parameters such as coercivity and magnetization besides the ferromagnetic behavior of both two series doped with Cobalt and Nickel. 相似文献
20.
In recent years, the utilization of nanoparticles for nano-magnetorheological fluid (NMRF) synthesis is gaining popularity in automotive applications. From this perspective, the nickel ferrite (NiFe 2O 4) nanoparticles were prepared by gel burning method and characterized using the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy-energy dispersive X-ray analysis (FESEM-EDX), and vibration sample magnetometer (VSM). The XRD and FTIR results showed the phase formation and characteristic metal–oxygen M–O vibrations. The FESEM images showed quasi-spherical crystallites with considerable agglomeration. The magnetic properties measured showed the ferromagnetic nature of NiFe 2O 4. The nanosized NiFe 2O 4 was used for NMRF preparation and characterization. 相似文献
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