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

Controllable Synthesis of CuxFe3−xO4@Cu Core–Shell Hollow Spherical Chains for Broadband, Lightweight Microwave Absorption

“…The analogous multiresonance behavior has also been observed in Fe 3 O 4 /Fe@C nanorings, [13] Mn x Fe 3Àx O 4 hollow/porous spherical chains, [4] Fe 3 O 4 /C core-shell nanorings, [29] Ni/MWCNT heterostructures (MWCNT = multiwalled carbon nanotubes, [53] and Fe/Fe 3 C/ MWCNT heterostructures. [8] Our data demonstratet hat the multiresonance behavior of the ferromagnetic matter is very sensitivet oi ts compositiona nd morphology.H ence, the magnetic loss of Cu 1.300 Fe 1.700 O 4 @Cu HSCs is attributed to natural resonance at low frequencies and exchange resonance at high frequencies.…”

“…Light absorption materials can be prepared by using two approaches:i )decreasing the absorber density by selecting hollow or porous structures [3,4] or decreasing the particle size to nanoscale [5] and ii)improving EM parameters to reduce the filling mass or volume fraction of the absorbers in the matrix. [6] Permittivity can be enhanced with the followings trategies:i )enhancement of space charge, ori-entation, or interface polarizationsb ym odulating the dimension, morphology, composition, and structure of absorbents; [7,8] using nanomaterials with low percolation threshold to form microcurrents through an electrical percolation network; [9,10] ii) selection of plasmonic structures( i.e.,r ings) as absorbers to generate plasmonic resonance-enhanced permittivity; [11,12] and iii)surface modification of the particles using other materials with high permittivity. [13] Surfacem odification can control the surfacea nd interfacec haracteristics of the magnetic nanoparticles, improve the stability of the structures, and functionalize the magnetic particles.…”

Facile Hydrothermal Synthesis of Fe3O4/C Core–Shell Nanorings for Efficient Low-Frequency Microwave Absorption

“…The development of electromagnetic (EM) wave absorbents has become a recent focus in solving EM pollution arising from the fast-growing electronic device industry. − The absorption properties of absorbents are determined by their permittivity (ε r = ε′ – j ε″), permeability (μ r = μ′ – j μ″), and matching, all of which depend on absorbent shape, composition, interface, and dimension. , Lately, many researchers have proved that the absorbents with single composition and structure were unable to meet the high remand for absorbing coatings of thin thickness, lightweight, broad bandwidth, and strong absorption. , Herein, we design and prepare elliptical Fe 3 O 4 /C nanorings (NRs) to improve absorption properties for several reasons. First, numerous studies demonstrate that NRs show enhanced absorption and multiresonant behaviors in the visible-to-near-infrared (NIR) regions, , as well as enhanced dielectric and absorption in microwave ranges. , The potential of ring-like nanostructures as microwave absorbents at 2–18 GHz, which has motivated our intense research interest, is unknown.…”

“…3,4 Lately, many researchers have proved that the absorbents with single composition and structure were unable to meet the high remand for absorbing coatings of thin thickness, lightweight, broad bandwidth, and strong absorption. 5,6 Herein, we design and prepare elliptical Fe 3 O 4 /C nanorings (NRs) to improve absorption properties for several reasons. First, numerous studies demonstrate that NRs show enhanced absorption and multiresonant behaviors in the visible-to-near-infrared (NIR) regions, 7,8 as well as enhanced dielectric and absorption in microwave ranges.…”

An experimental and CFD study on gas flow field distribution in the growth process of multi‐walled carbon nanotube arrays by thermal chemical vapor deposition

“…K. Hata et al obtained the A4 size single‐walled carbon nanotube forest by controlling the gas flow direction with the gas shower system . In recent years, the influence of parameters such as gas flow direction, gas flow rate, reaction temperature and reaction time are studied by many researchers . However, the gas flow field distribution in the quartz tube is not considered in the previous reports.…”