Journal of Materials Chemistry C
·
2021
·Vol. 9
·期 24
·7697-7705
·
IF 7.393
Wei Luo,Yi Liu,Chuangye Wang,Dan Zhao,Xiaoyan Yuan,Lei Wang,Jianfeng Zhu,Shouwu Guo,Xingang Kong
MAX phase solid solutions have attracted considerable attention owing to their unique structure and properties. However, the synthesis of MAX phase solid solutions doped with multi-elements at M-sites still remains a challenge. Herein, a series of (V1−x−yTixCry)2AlC solid solution powders are prepared through the reactions of V, Ti, Cr, and Al metals and graphite in molten NaCl/KCl salts, and their electromagnetic (EM) wave absorption properties are systematically investigated. In comparison with Ti2AlC, V2AlC and Cr2AlC, (V1−x−yTixCry)2AlC solid solutions exhibit prominent EM absorption performance. Specifically, the minimum reflection loss (RL) value of (V0.6Ti0.2Cr0.2)2AlC is −56.2 dB at 12.07 GHz with a sample thickness of 1.75 mm, and the optimized effective absorption bandwidth (EAB, RL < −10 dB) covers the whole X band with 4.16 GHz at 2.00 mm. Furthermore, the strong dielectric resonance is presented in the range of 7–13 GHz for all (V1−x−yTixCry)2AlC, indicating that both dipole polarization and conduction loss contribute to the excellent dielectric loss of doped MAX phases. Theoretical analysis demonstrates that the polarization loss is attributed to the anisotropic conductivity of MAX phases and M-site doping, which further weakens the electric conductivity. As a result, plenty of dipoles are involved and polarization relaxation occurred when the (V1−x−yTixCry)2AlC solutions are radiated by EM. Considering the numerous kinds of MAX phase solid solutions, this work paves the way to study the EM absorption performance of high-entropy or other MAX phase solid solutions.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS RESEARCH BULLETIN
·
2023
·
IF 5.4
Chengshuai Shao,Chunyan Ding,Songsong Wu,Yu Ma,Haichang Liu,Yu Liu,Xiaozhen Ren,Lijuan Zhang,Guangwu Wen,Xiaoxiao Huang
Currently, the absorbing bandwidth of the Ferrites is enormously limited at X-band and Ku-band by the poor intrinsic dielectric properties. Thus, there are few reports about the pure Ferrites’ application at 8-18 GHz. In this paper, the Ferrites composite foams (NFC) with a high surficial oxygen vacancy concentration (48.1%) were prepared by the NH 4 NO 3 assisted solution-combustion strategy and solid phase sintering. Noteworthily, the concentration of surficial oxygen vacancy can be effectively regulated by the NH 4 NO 3 . This is facilitated to achieve balanced impedance matching. Therefore, the effective absorption bandwidth (EAB) of the NFC covered the whole X-band and Ku-band. Conduction loss and defect polarization relaxation realized by surficial oxygen vacancies were confirmed to be the key to such wide EAB for the NFC at 8-18 GHz. This work explores the important role of surficial oxygen vacancy engineering in regulating the dielectric parameters of the Ferrites, and provides a feasible strategy of surficial oxygen vacancy engineering for wide EAB electromagnetic performance at the high-frequency.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2020
·
IF 4.65
Jianwen Ge,Yu Cui,Li Liu,Rui Li,Fandi Meng,Fuhui Wang
Rational design on the well wrapped core-shell microstructure of Co@ SiO x C composites was successfully conducted through reduction process of cobalt, efficient condensation reaction of KH-550 silane coupling agent as well as high temperature calcination . The SiO x C shell possessed 3D cross-linked network structure consisting of dielectric carbon and silicon composition for optimal electromagnetic matching. The microstructure, morphology, elements distribution, electromagnetic property and microwave absorption performance were fully characterized, respectively. This SiO x C shell effectively inhibited the agglomeration of cobalt particles, and regulated the complex electromagnetic parameters by decreasing permittivity and introducing polarization relaxation, all of which determined the efficient reflection loss with RL min value of −60.3 dB at 16.2 GHz and matching thickness of only 2.05 mm. Meanwhile, the effective absorption band is up to 7.1 GHz at 2.3 mm. By optimizing of core-shell structure and material components, the high-absorption performance was obtained through impedance matching, multi-interfacial polarizations, dipole (or defects) polarization and magnetic loss. Therefore, the Co@ SiO x C composites present a facile and promising route toward the design of large-scale-preparation and excellent microwave absorbing materials.
研究领域:
材料科学
·
电磁学
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2022
·
IF 10.319
Runrun Cheng,Yan Wang,Xiaochuang Di,Zhao Lu,Ping Wang,Xinming Wu
At present, the problem of electromagnetic wave (EMW) pollution is critical, and the design of high-performance absorbers is of great significance. Based on the synergy between dielectric and magnetic losses, and between multicomponents in heterostructures, the development of light-weight absorbers with a strong absorption capability and multiple scattering is a promising strategy to achieve high-performance absorbers. In this work, CoFe-MOF precursors with a bouquet-like structure were prepared via the hydrothermal method, and Co 7 Fe 3 /C and Co 9 S 8 /Fe/CoS 2 /C composites were obtained through a carbonization and sulfuration treatment during the high-temperature pyrolysis process, respectively. The experimental and theoretical results show that the Co 9 S 8 /FeCoS 2 /C composite has a better EMW absorption performance, and its optimal reflection loss (RL) value is -53.9 dB at a low filler loading of 20 wt.%, which is due to the S doping that enhances the interface polarization relaxation process and improves the impedance matching characteristics. Moreover, the Co 9 S 8 /FeCoS 2 /C composite can be as candidates of high-efficiency absorbers in extreme application environments.
研究领域:
材料科学
·
电磁学
·
环境科学
·
复合材料
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）