Metamaterials: Hierarchical Metamaterials for Multispectral Camouflage of Infrared and Microwaves (Adv. Funct. Mater. 10/2019)

Kim, Tae‐Hwan; Bae, Ji-Yeul; Lee, Namkyu; Cho, Hyung Hee

doi:10.1002/adfm.201970060

Cited by 36 publications

(57 citation statements)

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“…[ 17 ] Moreover, even with higher surface temperatures, their low emissivity endows such black materials with the counter‐intuitive ability to conceal themselves from IR detection due to their limited thermal radiation, showing great potential in multispectral (IR and visible) camouflage assisted by their dark colors. [ 4,18 ]…”

Section: Introductionmentioning

confidence: 99%

“…Visible black inorganic materials with intrinsically low IR emissivity (IR white) are scarce but of great significance for many areas, such as solar energy harvesting, [ 1,2 ] building thermal insulation, [ 3 ] multispectral camouflage, [ 4,5 ] and container package. [ 6 ] For instance, in solar–thermal conversion systems, to maximize the energy conversion efficiency, ideal solar absorbing materials should show perfect light absorption over the broad solar spectrum (0.3–2.5 µm), but simultaneously ultralow mid‐IR absorption/emission (2.5–20 µm) to suppress enormous heat dissipation via thermal re‐radiation (e.g., 0.68 kW m −2 @ 100 °C, 0.68 sun), known as spectrally selective solar absorption.…”

Section: Introductionmentioning

confidence: 99%

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2D Ti₃C₂T_x MXenes: Visible Black but Infrared White Materials

et al. 2021

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Black inorganic materials with low infrared absorption/emission (or IR white) are rare in nature but highly desired in numerous areas, such as solar–thermal energy harvesting, multispectral camouflage, thermal insulation, and anti‐counterfeiting. Due to the lack of spectral selectivity in intrinsic materials, such counter‐intuitive properties are generally realized by constructing complicated subwavelength metamaterials with costly nanofabrication techniques. Here, the intrinsically low mid‐IR emissivity (down to 10%) of the 2D Ti3C2Tx MXene is reported. Associated with a high solar absorptance (up to 90%), it embraces the best spectral selectivity among the reported intrinsic black solar‐absorbing materials. Its appealing potential in several of the aforementioned areas is experimentally demonstrated. First‐principles calculations reveal that the IR emissivity of MXene relies on both the nanoflake orientations and terminal groups, indicating great tunability. The calculations also suggest more potential low‐emissivity MXenes including Ti2CTx, Nb2CTx, and V2CTx. This work opens the avenue to further exploration of a family of intrinsically low‐emissivity materials with over 70 members.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

2D Ti₃C₂T_x MXenes: Visible Black but Infrared White Materials

et al. 2021

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“…Subwavelength electromagnetic (EM) wave absorbers are of substantial interest across all parts of the EM spectrum, [ 1–5 ] but are especially important for the MHz and GHz regimes due to their practical significance in stealth technology, [ 6,7 ] heat detection, [ 8 ] sensing, [ 9 ] and communication. [ 10 ] EM wave absorbers are particularly important for self‐driving vehicles or aerial systems, where insufficient protection against stray EM signals may lead to an electronic malfunction, posing a serious risk to human safety.…”

Section: Introductionmentioning

confidence: 99%

Coupled Solid and Inverse Antenna Stacks Above Metal Ground as Metamaterial Perfect Electromagnetic Wave Absorbers with Extreme Subwavelength Thicknesses

Kim

Jung

Choi

et al. 2022

Advanced Optical Materials

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The ability to completely absorb an electromagnetic (EM) wave with a material much thinner than the wavelength is a prerequisite for achieving ultracompact, flexible, and lightweight EM devices. Herein, a metamaterial microwave perfect absorber is demonstrated as thin as 1/1250 of the target wavelength by coupling an array of metal patches to inverse cross metal antennas through a dielectric separator and with a reflector placed underneath. Compared to a conventional three‐layer absorber, the modified design reduces the resonance frequency by up to tenfolds without altering the patch and dielectric layers, but by reconfiguring the induced current pathways that reorient the dipolar magnetic fields and dramatically boost the magnetic flux. With the reflector, the stack is framed for perfect absorption at the critical coupling condition, which is identified by monitoring the reflection phase shift across the resonance frequency. The study provides guidelines for shrinking the thickness further and can be extended to other frequencies.

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“…[ 16 ] These camouflage sheets should be in thermal insulation with the target so that it manifests the same temperatures as that of the background. Studies have reported on emissivity manipulation using paints, [ 17 ] metamaterials, [ 18–24 ] photonic crystals, [ 25–28 ] nanoantennas, [ 29 ] plasmonic structures, [ 30–32 ] phase change materials, [ 33–40 ] graphene, [ 41–43 ] and semiconductors. [ 44,45 ] Most current designs suffer from high specular reflectivity owing to low emissivity.…”

Section: Introductionmentioning

confidence: 99%

Infrared Camouflage Utilizing Ultrathin Flexible Large‐Scale High‐Temperature‐Tolerant Lambertian Surfaces

Huang

Pattanayak

et al. 2021

Laser & Photonics Reviews

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The development of ultrathin, flexible, large-scale, high-temperature-tolerant infrared camouflage devices, which are immune to the external environment, has emerged as an important unsolved challenge. This paper proposes an infrared camouflage device based on the Lambertian surface. The proposed device simultaneously exhibits low emissivity (≈0.1), low specular reflectance (≈0.05), and high temperature (290°C) tolerance over a broad infrared range (0.75-25 μm). Furthermore, the proposed device is ultrathin (≈50 μm), highly flexible, scalable, and can be fabricated at a low cost. The experimental results show that while camouflaging a target (at 65°C), the proposed Lambertian surface can reduce the peak value of the target-background contrast by 68.4% (indoor case) and 76.0% (outdoor case) compared to the conventional low-e (low-emissivity) smooth surface. The calculated detection range of the proposed low-e Lambertian surface is 60% less than that of both the low-e smooth surface and the blackbody. This work proposes a novel method to simultaneously control the radiation and the reflection, thereby introducing a new design paradigm for modern camouflage technology and energy harvesting applications.

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Metamaterials: Hierarchical Metamaterials for Multispectral Camouflage of Infrared and Microwaves (Adv. Funct. Mater. 10/2019)

Cited by 36 publications

References 0 publications

2D Ti₃C₂T_x MXenes: Visible Black but Infrared White Materials

2D Ti₃C₂T_x MXenes: Visible Black but Infrared White Materials

Coupled Solid and Inverse Antenna Stacks Above Metal Ground as Metamaterial Perfect Electromagnetic Wave Absorbers with Extreme Subwavelength Thicknesses

Infrared Camouflage Utilizing Ultrathin Flexible Large‐Scale High‐Temperature‐Tolerant Lambertian Surfaces

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Metamaterials: Hierarchical Metamaterials for Multispectral Camouflage of Infrared and Microwaves (Adv. Funct. Mater. 10/2019)

Cited by 36 publications

References 0 publications

2D Ti3C2Tx MXenes: Visible Black but Infrared White Materials

2D Ti3C2Tx MXenes: Visible Black but Infrared White Materials

Coupled Solid and Inverse Antenna Stacks Above Metal Ground as Metamaterial Perfect Electromagnetic Wave Absorbers with Extreme Subwavelength Thicknesses

Infrared Camouflage Utilizing Ultrathin Flexible Large‐Scale High‐Temperature‐Tolerant Lambertian Surfaces

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2D Ti₃C₂T_x MXenes: Visible Black but Infrared White Materials

2D Ti₃C₂T_x MXenes: Visible Black but Infrared White Materials