the light-responsive properties also have excellent adaptability to the environment. [7] Under the inspiration of these controllable optical properties, a variety of advanced material systems have been proposed significantly. [7,8] However, researchers were simply concentrated in a specific waveband due to the great difficulty to achieve the compatibility of multispectral properties, which greatly hinders advance science and the application fields expanding of novel photonic materials. For example, in order to avoid the detection of microwave radar, infrared detector, and visual observation, the stealth materials on military armament have been separately developed during microwave, infrared, and visible light range; [9][10][11] but the above stealth properties were difficult to be compatible in one weapon, thus, the problem of perfect stealth (stealth during full wavebands) is still not solved to date. Moreover, the material degradation by ultraviolet (UV) radiation also needs to be settled urgently because the weapons are exposed to sunlight all year round. Although metamaterials (MMs) researchers have conducted multibands studies, [12] such as optically transparent microwave absorbing materials, [13] multispectral absorption MMs, [14] and multibands resonators, [15] etc., only two or three bands were involved, and the multibands compatibility has not been deeply explored. When devices worked in real environments, dust particles accumulated on its surface over time, which would have an adverse effect on its light manipulation performance. In order to avoid this problem, it is desirable to integrate a self-cleaning ability induced by hydrophobic property of material into the equipment. [16] In this context, a hierarchical structure model of moth compound eye that might manipulate multibands EMWs was found here, as shown in Figure 1a. [17,18] This is a noctuid moth living in Heilongjiang Province of China; the hierarchical and sub-wavelength structures that are arranged in a highly ordered array of its eye surface could suppress the reflection of light to avoid detection by nocturnal predators and to see clearly in darkness, which is based on rigorous coupled wave analysis (RCWA) and finite difference time domain (FDTD) methods, [19] as well as relative research on moth eye model. [18,20] This feature makes the moth-eye model one of the most effective antireflective structures in nature. Although various photonic devices inspired by natural materials have been developed, there is no research focusing on multibands adaptability, whichis not conducive to the advancement of materials science. Herein, inspired by the moth eye surface model, state-of-the-art hierarchical metamaterials (MMs) used as tunable devices in multispectral electromagnetic-waves (EMWs) frequency range, from microwave to ultraviolet (UV), are designed and prepared. Experimentally, the robust broad bandwidth of microwave absorption greater than 90% (reflection loss (RL) < −10 dB) covering almost entire X and Ku bands (8.04-17.88 GHz) under a de...

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Electromagnetic (EM) absorbers serving in the megahertz (MHz) band and a wide temperature range (from −50 to 150 °C) require high and temperature-stable permeability for outstanding EM absorption performance. Herein, FeCoNiCr0.4Cu X high-entropy alloy (HEA) powders with a unique nanocrystalline structure separated by a thin amorphous layer (NTA) are designed to improve permeability and enhance intergranular coupling. Simultaneously, the long-range anisotropy is introduced via devising the preparation process and tuning the chemical composition, such that the intergranular exchange interaction is further strengthened for stable permeability and EM wave absorption in a wide temperature range. FeCoNiCr0.4Cu0.2 HEAs exhibit a near-zero permeability temperature coefficient (5.7 × 10–7 °C–1) a in wide temperature range. The maximum reflection loss (RL) of FeCoNiCr0.4Cu0.2 HEAs is higher than −7 dB with 5 mm thickness at −50–150 °C, and the absorption bandwidth (RL < −7 dB) can almost cover 400–1000 MHz. Furthermore, FeCoNiCr0.4Cu0.2 HEAs also have a high Curie temperature (770 °C) and distinguished oxidation resistance. The permeability temperature dependence of FeCoNiCr0.4Cu X HEAs is investigated in-depth in light of the microstructural change induced by tuning the chemical composition, and a new inspiration is provided for the design of magnetic applications serving in wide temperature, such as transformers, sensors, and EM absorbers.

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High-temperature electromagnetic (EM) protection materials integrated of multiple EM protection mechanisms and functions are regarded as desirable candidates for solving EM interference over a wide temperature range. In this work, a novel microwave modulator is fabricated by introducing carbonyl iron particles (CIP)/resin into channels of carbonized wood (C-wood). Innovatively, the spaced arrangement of two microwave absorbents not only achieves a synergistic enhancement of magnetic and dielectric losses, but also breaks the translational invariance of EM characteristics in the horizontal direction to obtain multiple phase discontinuities in the frequency range of 8.2–18.0 GHz achieving modulation of reflected wave radiation direction. Accordingly, CIP/C-wood microwave modulator demonstrates the maximum effective bandwidth of 5.2 GHz and the maximum EM protection efficiency over 97% with a thickness of only 1.5 mm in the temperature range 298–673 K. Besides, CIP/C-wood microwave modulator shows stable and low thermal conductivities, as well as monotonic electrical conductivity-temperature characteristics, therefore it can also achieve thermal infrared stealth and working temperature monitoring in wide temperature ranges. This work provides an inspiration for the design of high-temperature EM protection materials with multiple EM protection mechanisms and functions.

Electromagnetic wave loss caused by rotating polarization of chiral structures has long been considered as a disadvantage in transmission, detection, etc., however, it can be turned to benefit in microwave absorbing materials to enhance absorption. Herein, inspired by the chiral structure of jeweled beetles, gyrotropic metamaterials (MMs) are designed and prepared, and experimentally demonstrate the enhanced microwave absorption by rotating polarization; the bandwidth of absorptivity greater than 80% (reflection loss, RL ≤ −7 dB) covers the entire 4–18 GHz frequency range under an ultralow surface density of 1.45 kg m−2; the mechanism analyzed and verified by simulation models demonstrates this a universal method. A new paradigm of MMs fabricated by high entropy alloy (HEA) is offered in this work, which increases the freedom of MM design and promotes the integration of material science and physics. Multifarious wave adaptability and multifunctionality achieved by integrated HEA unit cell and foamed polyurethane realize ultrasonic and water wave absorption, as well as impact and corrosion resistance. These designs hold great promise for facilitating functionally integrated materials for stealth technology, antiterrorist, encryption, sensing, and photon detection.

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