A review and analysis of microwave absorption in polymer composites filled with carbonaceous particles
TL;DR: In this article, a perspective on the experimental efforts toward the development of microwave absorbers composed of carbonaceous inclusions in a polymer matrix is presented. But the authors focus on the application for which the absorber is intended, weight reduction and optimization of the operating bandwidth are two important issues.
Abstract: Carbon (C) is a crucial material for many branches of modern technology. A growing number of demanding applications in electronics and telecommunications rely on the unique properties of C allotropes. The need for microwave absorbers and radar-absorbing materials is ever growing in military applications (reduction of radar signature of aircraft, ships, tanks, and targets) as well as in civilian applications (reduction of electromagnetic interference among components and circuits, reduction of the back-radiation of microstrip radiators). Whatever the application for which the absorber is intended, weight reduction and optimization of the operating bandwidth are two important issues. A composite absorber that uses carbonaceous particles in combination with a polymer matrix offers a large flexibility for design and properties control, as the composite can be tuned and optimized via changes in both the carbonaceous inclusions (C black, C nanotube, C fiber, graphene) and the embedding matrix (rubber, thermoplastic). This paper offers a perspective on the experimental efforts toward the development of microwave absorbers composed of carbonaceous inclusions in a polymer matrix. The absorption properties of such composites can be tailored through changes in geometry, composition, morphology, and volume fraction of the filler particles. Polymercomposites filled with carbonaceous particles provide a versatile system to probe physical properties at the nanoscale of fundamental interest and of relevance to a wide range of potential applications that span radar absorption, electromagnetic protection from natural phenomena (lightning), shielding for particle accelerators in nuclear physics, nuclear electromagnetic pulse protection, electromagnetic compatibility for electronic devices, high-intensity radiated field protection, anechoic chambers, and human exposure mitigation. Carbonaceous particles are also relevant to future applications that require environmentally benign and mechanically flexible materials.
Citations
More filters
TL;DR: The incorporation of a second phase such as a metal and a conducting polymer greatly enhances the microwave-absorption capability and a remarkable reflection loss is achieved.
Abstract: Aligned carbon-nanotube (CNT) sheets are used as building blocks to prepare light-weight, frequency-tunable and high-performance microwave absorbers, and the absorption frequency can be accurately controlled by stacking them with different intersectional angles. A remarkable reflection loss of -47.66 dB is achieved by stacking four aligned CNT sheets with an intersectional angle of 90° between two neighboring ones. The incorporation of a second phase such as a metal and a conducting polymer greatly enhances the microwave-absorption capability.
745 citations
TL;DR: Considering the promising performance of Ti3C2 MXenes with the modified surface, this work is expected to open the door for the expanded applications of MXenes family in EM absorbing and shielding fields.
Abstract: Electromagnetic (EM) absorbing and shielding composites with tunable absorbing behaviors based on Ti3C2 MXenes are fabricated via HF etching and annealing treatment. Localized sandwich structure without sacrificing the original layered morphology is realized, which is responsible for the enhancement of EM absorbing capability in the X-band. The composite with 50 wt % annealed MXenes exhibits a minimum reflection loss of −48.4 dB at 11.6 GHz, because of the formation of TiO2 nanocrystals and amorphous carbon. Moreover, superior shielding effectiveness with high absorption effectiveness is achieved. The total and absorbing shielding effectiveness of Ti3C2 MXenes in a wax matrix with a thickness of only 1 mm reach values of 76.1 and 67.3 dB, while those of annealed Ti3C2 MXenes/wax composites are 32 and 24.2 dB, respectively. Considering the promising performance of Ti3C2 MXenes with the modified surface, this work is expected to open the door for the expanded applications of MXenes family in EM absorbing an...
691 citations
TL;DR: In this article, the authors introduce the theory of microwave absorption and summarize recent advances in the fabrication of graphene-based MAMs, including rational design of the microstructure of pure graphene and tunable chemical integrations with polymers, magnetic metals, ferrites, ceramics, and multicomponents composites.
Abstract: With the rapid arising of information technology, microwave absorbing materials (MAMs) are playing an increasingly significant role in electronic reliability, healthcare, and national defense security. Hence, development of high performance MAMs with thin thickness, low density, wide bandwidth, and strong absorption has attracted great interests. Recently, taking graphene as MAMs for high-performance electromagnetic (EM) wave attenuation has grabbed considerable attention, owing to their low density, high specific surface area, strong dielectric loss, and high electronic conductivity. Furthermore, in order to address the interfacial impedance mismatching of the sole graphene materials, incorporation of other lossy materials has been widely studied as the imperative solution to improve its MA performance. In this review, we introduce the theory of microwave absorption and summarize recent advances in the fabrication of graphene-based MAMs, including rational design of the microstructure of pure graphene and tunable chemical integrations with polymers, magnetic metals, ferrites, ceramics, and multicomponents composites. The key point of enhancing MA in graphene-based MAMs is to regulate their EM properties, improve of impedance matching, and create diversified loss mechanisms. Furthermore, the shortcomings, challenges, and prospects of graphene-based MAMs are also put forward, which will be helpful to people working in the related fields.
535 citations
TL;DR: In this article, the authors discussed the factors of microstructural defects, filler concentration, filler alignment, filler inherent conductivity and the surrounding temperature of carbon nanostructures and their composites.
531 citations
TL;DR: In this article, the maximum reflection loss of FeCo/graphene hybrids reaches −40.2 dB at 8.9 GHz with a matching thickness of only 2.5 mm, and the absorption bandwidth with reflection loss exceeding −10 dB is in the 3.4-18 GHz range for the absorber thickness of 1.5-5 mm.
Abstract: CoFe2O4/graphene oxide hybrids have been successfully fabricated via a facile one-pot polyol route, followed by chemical conversion into FeCo/graphene hybrids under H2/NH3 atmosphere. These magnetic nanocrystals were uniformly decorated on the entire graphene nanosheets without aggregation. The morphology, chemical composition and crystal structure have been characterized in detail. In particular, FeCo/graphene hybrids show significant improvement in both permeability and permittivity due to the combination of the high magnetocrystalline anisotropy of metallic FeCo and high conductivity of light-weight graphene. This leads to remarkable enhancement in microwave absorption properties. The maximum reflection loss of FeCo/graphene hybrids reaches −40.2 dB at 8.9 GHz with a matching thickness of only 2.5 mm, and the absorption bandwidth with reflection loss exceeding −10 dB is in the 3.4–18 GHz range for the absorber thickness of only 1.5–5 mm. Moreover, the experimental relationship between matching thickness and frequency is found to obey the quarter-wavelength matching model, facilitating the design of FeCo/graphene hybrid film for practical application. The results suggest that the FeCo/graphene hybrids developed here can serve as an ideal candidate for the manufacture of light-weight and high-efficiency microwave-absorbing devices.
471 citations
References
More filters
NEC1
TL;DR: Iijima et al. as mentioned in this paper reported the preparation of a new type of finite carbon structure consisting of needle-like tubes, which were produced using an arc-discharge evaporation method similar to that used for fullerene synthesis.
Abstract: THE synthesis of molecular carbon structures in the form of C60 and other fullerenes1 has stimulated intense interest in the structures accessible to graphitic carbon sheets. Here I report the preparation of a new type of finite carbon structure consisting of needle-like tubes. Produced using an arc-discharge evaporation method similar to that used for fullerene synthesis, the needles grow at the negative end of the electrode used for the arc discharge. Electron microscopy reveals that each needle comprises coaxial tubes of graphitic sheets, ranging in number from 2 up to about 50. On each tube the carbon-atom hexagons are arranged in a helical fashion about the needle axis. The helical pitch varies from needle to needle and from tube to tube within a single needle. It appears that this helical structure may aid the growth process. The formation of these needles, ranging from a few to a few tens of nanometres in diameter, suggests that engineering of carbon structures should be possible on scales considerably greater than those relevant to the fullerenes. On 7 November 1991, Sumio Iijima announced in Nature the preparation of nanometre-size, needle-like tubes of carbon — now familiar as 'nanotubes'. Used in microelectronic circuitry and microscopy, and as a tool to test quantum mechanics and model biological systems, nanotubes seem to have unlimited potential.
39,086 citations
[...]
TL;DR: Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena can now be mimicked and tested in table-top experiments.
Abstract: Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when commercial products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.
35,293 citations
TL;DR: In this paper, the basic theoretical aspects of graphene, a one-atom-thick allotrope of carbon, with unusual two-dimensional Dirac-like electronic excitations, are discussed.
Abstract: This article reviews the basic theoretical aspects of graphene, a one-atom-thick allotrope of carbon, with unusual two-dimensional Dirac-like electronic excitations. The Dirac electrons can be controlled by application of external electric and magnetic fields, or by altering sample geometry and/or topology. The Dirac electrons behave in unusual ways in tunneling, confinement, and the integer quantum Hall effect. The electronic properties of graphene stacks are discussed and vary with stacking order and number of layers. Edge (surface) states in graphene depend on the edge termination (zigzag or armchair) and affect the physical properties of nanoribbons. Different types of disorder modify the Dirac equation leading to unusual spectroscopic and transport properties. The effects of electron-electron and electron-phonon interactions in single layer and multilayer graphene are also presented.
20,824 citations
TL;DR: This study reports an experimental study of a condensed-matter system (graphene, a single atomic layer of carbon) in which electron transport is essentially governed by Dirac's (relativistic) equation and reveals a variety of unusual phenomena that are characteristic of two-dimensional Dirac fermions.
Abstract: Quantum electrodynamics (resulting from the merger of quantum mechanics and relativity theory) has provided a clear understanding of phenomena ranging from particle physics to cosmology and from astrophysics to quantum chemistry. The ideas underlying quantum electrodynamics also influence the theory of condensed matter, but quantum relativistic effects are usually minute in the known experimental systems that can be described accurately by the non-relativistic Schrodinger equation. Here we report an experimental study of a condensed-matter system (graphene, a single atomic layer of carbon) in which electron transport is essentially governed by Dirac's (relativistic) equation. The charge carriers in graphene mimic relativistic particles with zero rest mass and have an effective 'speed of light' c* approximately 10(6) m s(-1). Our study reveals a variety of unusual phenomena that are characteristic of two-dimensional Dirac fermions. In particular we have observed the following: first, graphene's conductivity never falls below a minimum value corresponding to the quantum unit of conductance, even when concentrations of charge carriers tend to zero; second, the integer quantum Hall effect in graphene is anomalous in that it occurs at half-integer filling factors; and third, the cyclotron mass m(c) of massless carriers in graphene is described by E = m(c)c*2. This two-dimensional system is not only interesting in itself but also allows access to the subtle and rich physics of quantum electrodynamics in a bench-top experiment.
18,958 citations
TL;DR: This review analyzes recent trends in graphene research and applications, and attempts to identify future directions in which the field is likely to develop.
Abstract: Graphene is a wonder material with many superlatives to its name. It is the thinnest known material in the universe and the strongest ever measured. Its charge carriers exhibit giant intrinsic mobility, have zero effective mass, and can travel for micrometers without scattering at room temperature. Graphene can sustain current densities six orders of magnitude higher than that of copper, shows record thermal conductivity and stiffness, is impermeable to gases, and reconciles such conflicting qualities as brittleness and ductility. Electron transport in graphene is described by a Dirac-like equation, which allows the investigation of relativistic quantum phenomena in a benchtop experiment. This review analyzes recent trends in graphene research and applications, and attempts to identify future directions in which the field is likely to develop.
12,117 citations