The electromagnetic parameters were measured for the mixtures of mechanical milled carbonyl iron powders （CIPs） with different mass ratios of spheroid-like particles to flake-shape particles. The results indicate th...The electromagnetic parameters were measured for the mixtures of mechanical milled carbonyl iron powders （CIPs） with different mass ratios of spheroid-like particles to flake-shape particles. The results indicate that mixing the sphere-like CIP particles with flake-shaped CIPs can be used to adjust effectively the electromagnetic parame- ters and enhance the absorption property in high frequency. In addition, a theoretic simulation based on the principle of superposition was carried out and compared with the microwave measurement results, indicating that the simple principle of superpo- sition can not reflect truly the internal interaction mechanism in the composites with different particle shapes.展开更多
Ni/Al2O3 nanocomposites were prepared by the mechanochemical synthesis method. The annealing process enlarges the grain size of both the metal Ni and insulating Al2O3 in the as-milled nanocomposite and leads to an inc...Ni/Al2O3 nanocomposites were prepared by the mechanochemical synthesis method. The annealing process enlarges the grain size of both the metal Ni and insulating Al2O3 in the as-milled nanocomposite and leads to an increase of the saturation magnetization and a decrease of the surface anisotropy. An optimal reflection loss （RL） of -23 dB is obtained in the as-milled nanocomposite at 17.8 GHz for an absorber thickness of 6.6 mm. The annealed sample exhibits a RL exceeding -20 dB in the whole Ku-band for an absorber thickness of 6.6-9.7 mm with an optimal RL of -54.7 dB at 13.2 GHz for a layer thickness of 9.3 mm. The excellent microwave-absorption properties are a consequence of a proper match of the dielectric and magnetic losses.展开更多
Dielectric properties of SiC/Ni nanocomposites prepared by a simple and facile electroless plating approach at X band are investigated. Compared to the original SiC nanopartieles （SiCp）, the real part of the permitt...Dielectric properties of SiC/Ni nanocomposites prepared by a simple and facile electroless plating approach at X band are investigated. Compared to the original SiC nanopartieles （SiCp）, the real part of the permittivity, ε＇, and the dielectric loss tangent tang δe of SiC/Ni nanocomposites are clearly enhanced by about 31% and 33%, respectively. The effective equations for complex permittivity of SiC/Ni nanoeomposites are proposed. We also calculate ε＇ and tan δe of SiC/Ni nanoeomposites and the calculated results are well consistent with the measured data.展开更多
基金supported by National High Technical Research and Development Program of China(No.2006AA03A209)New Century Excellent Talents(No.NCET-05-0660)from the Ministry of Education,China Postdoctoral Science Fund(No.20100480886)University Industry Cooperation project(Guangdong financial education[2011]362)from Guangdong Province and Fundamental Research Funds for the Central Universities(2011-IV-059)
文摘The electromagnetic parameters were measured for the mixtures of mechanical milled carbonyl iron powders （CIPs） with different mass ratios of spheroid-like particles to flake-shape particles. The results indicate that mixing the sphere-like CIP particles with flake-shaped CIPs can be used to adjust effectively the electromagnetic parame- ters and enhance the absorption property in high frequency. In addition, a theoretic simulation based on the principle of superposition was carried out and compared with the microwave measurement results, indicating that the simple principle of superpo- sition can not reflect truly the internal interaction mechanism in the composites with different particle shapes.
基金financially supported by the Dr.Research Start-up Fund of Shenyang Ligong University(No.2008,(20))
文摘Ni/Al2O3 nanocomposites were prepared by the mechanochemical synthesis method. The annealing process enlarges the grain size of both the metal Ni and insulating Al2O3 in the as-milled nanocomposite and leads to an increase of the saturation magnetization and a decrease of the surface anisotropy. An optimal reflection loss （RL） of -23 dB is obtained in the as-milled nanocomposite at 17.8 GHz for an absorber thickness of 6.6 mm. The annealed sample exhibits a RL exceeding -20 dB in the whole Ku-band for an absorber thickness of 6.6-9.7 mm with an optimal RL of -54.7 dB at 13.2 GHz for a layer thickness of 9.3 mm. The excellent microwave-absorption properties are a consequence of a proper match of the dielectric and magnetic losses.
文摘Dielectric properties of SiC/Ni nanocomposites prepared by a simple and facile electroless plating approach at X band are investigated. Compared to the original SiC nanopartieles （SiCp）, the real part of the permittivity, ε＇, and the dielectric loss tangent tang δe of SiC/Ni nanocomposites are clearly enhanced by about 31% and 33%, respectively. The effective equations for complex permittivity of SiC/Ni nanoeomposites are proposed. We also calculate ε＇ and tan δe of SiC/Ni nanoeomposites and the calculated results are well consistent with the measured data.
