High‐Entropy Enhanced Microwave Attenuation in Titanate Perovskites

Advanced Materials, Journal Year: 2023, Volume and Issue: 35(11)

Published: Jan. 6, 2023

High-entropy oxides (HEOs), which incorporate multiple-principal cations into single-phase crystals and interact with diverse metal ions, extend the border for available compositions unprecedented properties. Herein, a high-entropy-stabilized (Ca0.2 Sr0.2 Ba0.2 La0.2 Pb0.2 )TiO3 perovskite is reported, effective absorption bandwidth (90% absorption) improves almost two times than that of BaTiO3 . The results demonstrate regulation entropy configuration can yield significant grain boundaries, oxygen defects, an ultradense distorted lattice. These characteristics give rise to strong interfacial defect-induced polarizations, thus synergistically contributing dielectric attenuation performance. Moreover, large strains derived from lattice distortions in high-entropy offer varied transport electron carriers. high-entropy-enhanced positive/negative charges accumulation around boundaries strain-concentrated location, quantitatively validated by holography, unusual polarization loss. This study opens up avenue designing microwave materials satisfy increasingly demanding requirements advanced integrated electronics. work also offers paradigm improving other interesting properties HEOs through engineering.

Language: Английский

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Confined Diffusion Strategy for Customizing Magnetic Coupling Spaces to Enhance Low‐frequency Electromagnetic Wave Absorption

Advanced Functional Materials, Journal Year: 2023, Volume and Issue: 33(16)

Published: Feb. 7, 2023

Abstract The rational design of magnetic composites has great potential for electromagnetic (EM) absorption, particularly in the low‐frequency range 2–8 GHz. However, scalable synthesis such absorbers with both high content and good dispersity remains challenging. In this study, a confined diffusion strategy is proposed to fabricate functional magnetic‐carbon hollow microspheres. Driven by ferromagnetic enhanced Kirkendall effect, situ alloying FeCo nanoparticles tightly carbon shells, effectively inhibiting agglomeration. Moreover, core–shell FeCo–carbon nano‐units further assemble into dispersive microscale Janus bulges on inner outer surfaces microsphere. optimized FeCo@C microspheres exhibit excellent EM wave absorption performance: minimum reflection loss ( RL min ) −35.9 dB, bandwidth covers almost entire C‐band. Systematic investigation reveals that large size integration, high–density units, strong coupling are essential enhancing dissipation waves. This study provides novel fabricating advanced significant inspiration investigating attenuation mechanism at low frequency.

Language: Английский

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Shape Anisotropic Chain‐Like CoNi/Polydimethylsiloxane Composite Films with Excellent Low‐Frequency Microwave Absorption and High Thermal Conductivity

Advanced Functional Materials, Journal Year: 2024, Volume and Issue: unknown

Published: Feb. 13, 2024

Abstract The demand for low‐frequency microwave absorption materials is becoming more and urgent. Novel shape anisotropy chain‐like CoNi fabricated using polyvinylpyrrolidone as a shape‐directing agent via solvothermal method, which then mixed with polydimethylsiloxane (PDMS) to prepare corresponding multifunctional CoNi/PDMS composite films. Shape strong magnetic coupling effect of enhance natural resonance loss capability. minimum reflection (RL min ) −50.5 dB effective bandwidth (EAB) 1.04 GHz (2.64–3.68 GHz) at 3.9 mm CoNi. 18 vol% films present optimal performance RL −56.7 EAB (2.96–4.00 4.1 mm, far superior spherical −9.5 dB. Meantime, the in‐plane inter‐plane thermal conductivity coefficients are 2.05 0.61 W m −1 K , about 1.5 times higher than (1.36 0.42 ), also 220% 190% pure PDMS (0.64 0.21 ). This can broaden applications in 5G communications flexible electronics.

Language: Английский

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Staggered circular nanoporous graphene converts electromagnetic waves into electricity

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: April 8, 2023

Harvesting largely ignored and wasted electromagnetic (EM) energy released by electronic devices converting it into direct current (DC) electricity is an attractive strategy not only to reduce EM pollution but also address the ever-increasing crisis. Here we report synthesis of nanoparticle-templated graphene with monodisperse staggered circular nanopores enabling EM-heat-DC conversion pathway. We experimentally theoretically demonstrate that this nanoporous structure alters graphene's phononic properties synergistically manipulating its intralayer nanostructures interlayer interactions. The exhibits anomalous combination properties, which lead efficient absorption waves heat in turn output DC through thermoelectric effect. Overall, our results advance fundamental understanding structure-property relationships ordered graphene, providing effective generate electric energy.

Language: Английский

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Multiphase Molybdenum Carbide Doped Carbon Hollow Sphere Engineering: The Superiority of Unique Double‐Shell Structure in Microwave Absorption

Small, Journal Year: 2022, Volume and Issue: 19(6)

Published: Nov. 27, 2022

In order to achieve excellent electromagnetic wave (EMW) absorption properties, the microstructure design and component control of absorber are critical. this study, three different structures made Mo2 C/C hollow spheres prepared their microwave behavior is investigated. The double-shell consisting an outer thin shell inner rough thick with multiple EMW loss mechanisms exhibit good properties. further improve MoC1-x /C crystalline phases molybdenum carbide optimize capability materials. Finally, α-phase have best When filling 20 wt.%, minimum reflection at 1.8 mm -50.55 dB effective bandwidth 2 5.36 GHz, which expected be a characteristics "thin, light, wide, strong".

Language: Английский

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Multifunctional MXene/C Aerogels for Enhanced Microwave Absorption and Thermal Insulation

Nano-Micro Letters, Journal Year: 2023, Volume and Issue: 15(1)

Published: Aug. 9, 2023

Two-dimensional transition metal carbides and nitrides (MXene) have emerged as promising candidates for microwave absorption (MA) materials. However, they also some drawbacks, such poor impedance matching, high self-stacking tendency, density. To tackle these challenges, MXene nanosheets were incorporated into polyacrylonitrile (PAN) nanofibers subsequently assembled a three-dimensional (3D) network structure through PAN carbonization, yielding MXene/C aerogels. The 3D effectively extends the path of microcurrent transmission, leading to enhanced conductive loss electromagnetic (EM) waves. Moreover, aerogel's rich pore significantly improves matching while reducing density MXene-based absorbers. EM parameter analysis shows that aerogels exhibit minimum reflection (RLmin) value - 53.02 dB (f = 4.44 GHz, t 3.8 mm), an effective bandwidth (EAB) 5.3 GHz (t 2.4 mm, 7.44-12.72 GHz). Radar cross-sectional (RCS) simulations employed assess radar stealth effect aerogels, revealing maximum RCS reduction perfect electric conductor covered by aerogel reaches 12.02 m2. In addition MA performance, demonstrates good thermal insulation 5-mm-thick can generate temperature gradient over 30 °C at 82 °C. This study provides feasible design approach creating lightweight, efficient, multifunctional

Language: Английский

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Metal Ions Confined in Periodic Pores of MOFs to Embed Single‐Metal Atoms within Hierarchically Porous Carbon Nanoflowers for High‐Performance Electromagnetic Wave Absorption

Advanced Functional Materials, Journal Year: 2022, Volume and Issue: 33(7)

Published: Nov. 30, 2022

Abstract Nanocarbons with single‐metal atoms (M‐SAs) have displayed considerable potential in various fields of application due to high free energy M‐SAs and strong metal‐support interaction. However, the uniform dispersion within whole carbon matrix still remains a great challenge. Herein, Ni‐SAs are uniformly dispersed hierarchically porous nanoflowers (Ni‐SA/HPCF) via spatial confinement Ni ions periodic pores metal‐organic frameworks (MOFs) subsequent carbonization process. The Ni‐SA/HPCF abundant mesopores an ultrahigh surface area (1137.2 m 2 g −1 ) exhibits unexpected electromagnetic wave (EMW) absorption property minimal reflection loss –53.2 dB effective bandwidth 5.0 GHz, while filler ratio is merely 10 wt.%. Density functional theory calculations experimental results reveal that break local symmetry electronic structure increase electrical conductivity host matrix, thereby enhancing EMW properties. In addition, unique 3D hierarchical morphology boosts impedance matching property, which synergistically improves performance Ni‐SA/HPCF. This study provides efficient approach disperse nanocarbons for other applications.

Language: Английский

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Tuning microwave absorption properties of Ti3C2T MXene-based materials: Component optimization and structure modulation

Journal of Material Science and Technology, Journal Year: 2023, Volume and Issue: 148, P. 150 - 170

Published: Jan. 6, 2023

Language: Английский

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Constructing multiple heterogeneous interfaces in one-dimensional carbon fiber materials for superior electromagnetic wave absorption

Carbon, Journal Year: 2024, Volume and Issue: 226, P. 119233 - 119233

Published: May 11, 2024

Language: Английский

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Three-dimensional conductive network constructed by in-situ preparation of sea urchin-like NiFe2O4 in expanded graphite for efficient microwave absorption

Journal of Colloid and Interface Science, Journal Year: 2023, Volume and Issue: 650, P. 710 - 718

Published: July 7, 2023

Language: Английский

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