Prepared and Microwave-Absorption Properties of BN Coated Ni Nanocapsules

Abstract

BN coated Ni nanocapsules were prepared by arc evaporating Ni-B amorphous alloy powders synthesized by a mechanochemical reaction, and their microstructure, surface component as well as electromagnetic properties (2-18 GHz) were investigated by means of high-resolution transmission electron microscopy, X-ray diffraction , photoluminescence spectra (PL) and a network analyzer, respectively. The reflection loss R (dB) of the nanocapsules less than -20 dB was obtained in the frequency range of 4.3-18 GHz for an absorber thickness of 1.4-6 mm. An optimal reflection loss of -32.0 dB was reached at 13 GHz with an absorber thickness of 2 mm. The microwave absorptive mechanisms of BN-coated Ni nanocapsule absorbent were discussed.

A Two-Step Method Synthesis and Microwave Absorption Properties of Double-Shell Ni@/BN@BaTiO₃Nanocapsules

“…Ni@/BN nanocapsules consisting of a Ni core and BN shell were prepared by arc-discharge in our previous study [8]. Here BaTiO 3 shell was coated on the surface of Ni@/BN nanocapsules to form core double-shell Ni@/BN@BaTiO3 nanocomposites by a chemical liquid deposition method subsequently, which is similar to the method reported in ref.…”

“…The microstructure, phase, surface compositions as well as electromagnetic(EM) properties(1-18GHz) were investigated by means of high-resolution transmission electron microscopy(JEOL 2010 EX HRTEM), X-ray diffraction (XRD) with Cu Ka (λ = 0.15405 nm), FT-IR (IR-Prestige-21), and Vector network analyzer (ENA E5071C), respectively. The RL in the composite were determined by values of ε′, ε″, µ ′ and µ" based on a model of a single-layered plane wave absorber proposed by Naito and Suetake [6][7][8][9][10].…”

“…The reason is that this type of EM wave absorbers not only possess a high saturation magnetization and Snoek's limit at high frequencies, but also decrease eddy current phenomenon induced by electromagnetic wave. Nanocapsules with shell of graphite C [4], SmO [5], Y 2 O 3 [6], ZnO [7], BN [8],etc. were synthesized.…”

Effects of Boron Nitride Coatings at High Temperatures and Electromagnetic Wave Absorption Properties of Carbon Fiber-Based Magnetic Materials

“…After the deposition of the BN coating, a film was formed on the surface of the CF. This film enhances the heat resistance of the material and may also enhance the absorbing properties of the material in certain conditions [22]. The surface of the CF that is not covered with the BN coating contains no film, and only the magnetic particles are distributed.…”

Graphene/BN/Fe/BN Nanocomposites for Highly Efficient Electromagnetic Wave Absorption

“…More importantly, a BN layer with lower electrical conductivity exhibits both the impedance matching characteristic and electromagnetic wave absorbing attenuation in the process of multiple reflections, electrical conductivity loss, dipole polarization, and interfacial polarization . All of the above characteristics indicate that regardless of whether BN is combined with a metal absorber or a nonmetal absorber, the impedance matching and comprehensive performance of microwave absorbers can be optimized. − Another effective method is to construct specific structures, such as core–shell, which are conducive to building multiple interfaces, increasing interface polarization, and improving the microwave absorption performance. − …”