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Effect of Laser Ablation on Microwave Attenuation Properties of Diamond Films
摘要： Thermal conductivity is required for developing high-power microwave technology. Diamond has the highest thermal conductivity in nature. In this study, a diamond ?lm was synthesized by microwave plasma chemical deposition, and then long and short conductive graphite ?bers were introduced to the diamond ?lms by laser ablation. The permittivity of the samples in the K-band was measured using the transmission/re?ection method. The permittivity of diamond ?lms with short graphite ?bers increased. The increase in real part of permittivity can be attributed to electron polarization, and the increase in the imaginary part can be ascribed to both polarization and electrical conductivity. The diamond ?lms with long graphite ?bers exhibited a highly pronounced anisotropy for microwave. The calculation of microwave absorption shows that re?ection loss values exceeding ?10 dB can be obtained in the frequency range of 21.3–23.5 GHz when the graphite ?ber length is 0.7 mm and the sample thickness is 2.5 mm. Therefore, diamond ?lms can be developed into a microwave attenuation material with extremely high thermal conductivity.
关键词： high thermal conductivity,laser ablation,diamond ?lms,microwave attenuation,permittivity
更新于2025-09-12 10:27:22
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Constructing excellent electromagnetic wave absorber with dielectric-dielectric media based on 3D reduced graphene and Ag(I)-Schiff base coordination compounds
摘要： The dielectric-dielectric composite (SRGA) for electromagnetic absorber was fabricated via integrating Ag(I)-Schiff base coordination compounds (SSBCC) with three-dimensional reduced graphene aerogel (3D-rGA) powders. SRGA showed excellent electromagnetic wave absorption properties in terms of re?ection loss, absorption band width and absorber thickness. Specially, when the mass ratio of SSBC to 3D-rGA powders was 1:3 (SRGA-25), the maximum value of re?ection loss at 2 mm was up to (cid:1)63.82 dB and the effective frequency bandwidth of 6.28 GHz (10.16e16.44 GHz) at 2.5 mm can be obtained. The mechanism investigation of electromagnetic wave absorption for SRGA showed that the enhanced electromagnetic wave absorption was ascribed to enhanced polarization loss derived from good 3D-conductive-network units of 3D-rGA, abundant interfaces caused by the media heterostructure due to the introduction of SSBCC and the good impedance matching condition. And 3D-rGA based materials might be put into practical application only in powder state due to the very low strength of the buck state. Therefore, the investigation on SRGA in our contribution is considered to be an actual performance evaluation of the materials based on three-dimensional graphene for microwave attenuation. This work also provided a method for fabricating excellent graphene-based electromagnetic wave absorbers by simply mixing a suitable dielectric lossy material, e.g. SSBCC.
关键词： Electromagnetic wave absorber,Schiff base,Composite,Microwave attenuation,Graphene aerogel
更新于2025-09-04 15:30:14