Fe Nanofibers Research Articles

Polyvinylpyrrolidone mediated electrospun ZnO-ZnFe2O4 composite nanofibers for removing malachite green from water

This study explores the application of ZnO-ZnFe2O4 composite nanofibers for the adsorption of Malachite Green (MG) dye from water. The composite nanofibers were fabricated using simple polyvinylpyrrolidone (PVP) mediated electrospinning method by changing zinc and iron precursor weight ratio named as Zn–Fe (1-1), Zn–Fe (2–1) and Zn–Fe (1–2). The diameter of 1D nanofibers was found to be 40–60 nm. The formation of hexagonal wurtzite structure of ZnO and cubic spinel structure of ZnFe2O4 was confirmed by XRD and HRTEM analysis. The effects of various parameters such as pH, contact time and initial concentration on the adsorption process were investigated. The Zn–Fe (1-1) nanofibers showed higher adsorption efficiency than other two. The adsorption results demonstrated excellent adsorption performance, with a maximum adsorption capacity of 146.77 mg/g at pH = 7 for Zn–Fe (1-1). Furthermore, the adsorption kinetics and isotherms were analyzed to understand the adsorption mechanism and equilibrium behaviour. It was found that the nanofibers material can be recycled and reused up to five cycles.

Broadband and strong microwave absorption of Fe/Fe3C/C core–shell spherical chains enhanced by dual dielectric relaxation and dual magnetic resonances

By utilizing a simple calcination process in the presence of Fe nanofibers (NFs) and benzene under N2, we synthesized large amounts of Fe@Fe3C@C core–shell spherical chains (CSSCs) comprising soft magnetic (Fe@Fe3C) NFs as cores and disordered C as shells. Varying the benzene volume from 1 mL to 4 mL conveniently modulated the C/Fe atom ratio over the range of 0–0.283. The composition-dependent static magnetic and microwave absorption properties of the Fe@Fe3C@C CSSCs were systemically investigated. The Fe@Fe3C@C CSSCs with a C/Fe atom ratio of 0.166–0.283 exhibited excellent microwave absorption properties, having stronger absorption and broader bandwidth than other absorbers. An optimal reflection loss (RL) value of −58.0 dB was observed at 8.68 GHz under an absorber thickness of 2.4 mm. The absorption bandwidth (RL ≤ −20 dB, 99% absorption) also reached as high as 16 GHz, which corresponded to the absorber thickness of 1.2–8.0 mm. The mechanism underlying the enhancement in microwave absorption was determined to be the synergy of dual dielectric relaxation, dual magnetic resonances, high attenuation, and good impedance matching caused by the 1D structure, core–shell structure, and heterostructure. The high microwave absorption capacity and wide absorption bandwidth demonstrated the promising practical applications of the Fe@Fe3C@C CSSCs.

<p>Synthesis and Electromagnetic Wave Absorbing Property of BaTiO3@Fe Nanofibers with Core-Shell Structure</p>

-coated Fe nanofibers are synthesized via a three-step process. nanofibers with an average diameter of approximately 200 nm are first prepared using an electrospinning process followed by a calcination step. The coating layer on the nanofiber is formed by a sol-gel process, and a thermal reduction process is then applied to the core-shell nanofiber to selectively reduce the to Fe. The thickness of the shell is controlled by varying the reaction time. To evaluate the electromagnetic (EM) wave-absorbing abilities of the nanofiber, epoxy-based composites containing the nanofibers are fabricated. The composites show excellent EM wave absorption properties where the power loss increases to the high frequency region without any degradation. Our results demonstrate that the nanofibers obtained in this work are attractive candidates for electromagnetic wave absorption applications.

Easy gas-flow-induced CVD synthesis and tunable electromagnetic characteristics of centipede-shaped iron/cementite/multiwalled carbon nanotube (Fe/Fe3C/MWCNT) heterostructures

Abstract Centipede-shaped iron/cementite/multiwalled carbon nanotube (Fe/Fe 3 C/MWCNT) heterostructures were synthesized via a novel and easy gas-flow-induced in situ two-step chemical vapour deposition (CVD) method for the first time. The formation mechanism was studied via X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The cooperation between the carrier gas flow and the spontaneous magnetization caused the assembly of Fe nanocrystals from the pyrolysis of Fe(CO) 5 into Fe nanofibers, which subsequently functioned as substrates and catalyst precursors for Fe 3 C-catalyzed MWCNT growth. The aspect ratio and the MWCNT content of the products were easily controlled by changing the feeding ratio of Fe(CO) 5 volume to polyethylene glycol 20 000 (PEG 20 000) mass. The electromagnetic property study revealed that increasing the aspect ratio and length can improve the material's dielectric properties. Simulation studies show that 40 wt.% of Fe/Fe 3 C/MWCNT heterostructures in a wax matrix exhibits high values of reflection loss (

Method for analyzing the magnetic anisotropy in non-aligned Fe nanofibers via electrospinning

In order to investigate the magnetic anisotropy of non-aligned Fe nanofibers, electrospinning and heat treatment techniques were successfully used to prepare novel Fe nanofibers. A new method was offered to characterize the magnetic anisotropy only using VSM combining with Mössbauer spectroscopy techniques. It is found that each individual nanofiber was uniform and straight on the whole measurement substrate with little breakage and Mössbauer spectroscopy result shows that all magnetic moments lied in the EA of nanofibers. With simple numerical calculation and fitting with experimental data, the magnetic anisotropy Ha of non-aligned Fe nanofibers was obtained and the result shows that the shape anisotropy dominates the overall magnetic anisotropy in the Fe nanofibers. This method provides a rapid and effective access to analyze and measure the magnetic anisotropy of soft magnetic nanofibers.

Fabrication and electromagnetic properties of fe nanofibers composites

In order to develop electromagnetic (EM) wave absorbing materials in the giga-hertz (GHz) frequency range, Fe nanofibers have been prepared by multi-nozzle electrospinning process (ESP) and heat treatments. The effects of applied voltage and feed rate on the morphology of electrospun PVP/Fe salt nanofibers have been studied in the electrospinning process. The average diameter and the standard deviation of electrospun nanofibers tend to decrease with the increase of the applied voltage and the decrease of the feed rate, respectively. Through the heat treatments of calcination and H2 reduction, as-spun PVP/Fe salt has been stepwise transformed into Fe2O3, Fe3O4, and Fe phases. To evaluate the EM characteristic of the prepared Fe nanofibers, epoxy matrix composites containing Fe nanofibers of 10 and 30 wt% have been fabricated. The Fe nanofibers have improved the EM characteristics of composites as compared to those of nano-sized metallic particles.

Solution synthesis and novel magnetic properties of ball-chain iron nanofibers

Abstract

Preparation and Characterization of TiO2 Coated Fe Nanofibers for Electromagnetic Wave Absorber

Recently, electromagnetic interference (EMI) and electromagnetic compatibility (EMC) have become serious problems due to the growth of electronic device and next generation telecommunication. It is necessary to develop new electromagnetic wave absorbing material to overcome the limitation of electromagnetic wave shielding materials. The EMI attenuation is normally related to magnetic loss and dielectric loss. Therefore, magnetic material coating dielectric materials are required in this reason. In this study, TiO2 coated Fe nanofibers were prepared to improve their properties for electromagnetic wave absorption. Poly(vinylpyrrolidone) (PVP) and Iron (III) nitrate nonahydrate (Fe(NO3)3 x 9H2O) were used as starting materials for the synthesis of Fe oxide nanofibers. Fe oxide nanofibers were prepared by electrospinning in an electric field and heat treatment. TiO2 layer was coated on the surface of Fe oxide nanofibers using sol-gel process. After the reduction of TiO2 coated Fe oxide nanofibers, Fe nanofibers with a TiO2 coating layer of about 10 nm were successfully obtained. The morphology and structure of fibers were characterized by SEM, TEM, and XRD. In addition, the absorption properties of TiO2 coated Fe nanofibers were measured by network analyzer.

Iron Nanofibers Synthesized by the Electrospinning Method for Use as a GHz Band Electromagnetic Wave Absorber

In this study, we fabricated Fe nanofibers that had a high aspect ratio and were coated by an oxidation protection layer, because electromagnetic properties are affected by the aspect ratio and oxidized layers. PVP/Fe salt nanofibers were prepared by an electrospinning method using an optimized concentration of PVP solution with Iron(lll) nitrate nonahydrate (Fe (NO3)3.9H2O) solution to apply a high voltage. Subsequently, to prepare the Fe nanofibers, the PVP/Fe salt nanofibers were heated up to 600 degrees C in air and reduced to 450 degrees C in H2. The Fe nanofibers were then coated by PVP to prevent re-oxidation. The S-parameter of the prepared Fe nanofibers was measured by a network analyzer, and the power loss was calculated to estimate the EM absorption ability.

Synthesis and Characterization of Fe Nanofiber using Alumina with Nanoholes by Anodic Oxidation

Alumina with nanoholes was prepared by anodic oxidation of aluminium and subsequently the synthesis of Fe nanofibers was attempted using nanoholes in alumina as a template. Various Fe nanofibers were synthesized by electroplating into alumina templates and subsequent chemical treatments in mixed-acid solutions to remove the templates. Obtained Fe nanofibers had the dimension with 20 nm-30 nm in diameters and typically 500 nm-2 μm in length. Effect of anodic oxidation treatments for a template on the microstructure of Fe nanofibers was examined. The length of Fe nanofibers could be changed by modifying the synthetic conditions, such as anodic oxidation times and electroplating times.