Stacking faults induced high dielectric permittivity of SiC wires

Abstract

Silicon carbide (SiC) is considered to be one of the promising EM absorbing materials due to its good oxidation resistance, low density and chemical inertness, and can be used in high-temperature and harsh environments. In this paper, C-SiC wires with different stacking faults densities were prepared by microwave heating following with post heat-treatment under different conditions. Dielectric measurements indicate that their permittivities increase with the increase in stacking faults density in 2-18 GHz. TEM observation suggests that the stacking faults were formed by embedding 2H-SiC segments in 3C-SiC matrix, which resulting in the type-II 2H/3C-SiC heterostructures. Since both the VBM and CBM of 3C-SiC are lower than those of 2H-SiC, respectively, a large conduction-band offset would occur. This may cause plenty of interface dipoles and following with large dipole polarization loss, which might be the origin of high dielectric permittivity of SiC wires.

Conductivity-dependent dielectric properties and microwave absorption of Al-doped SiC whiskers

“…This good microwave absorption ability is also affected by other factors. The SF density is described by the intensity ratio between SF and SiC(200) X-ray diffraction peak, and these values are found to reduce slightly with the increase in dopant amount, are 2.69, 2.60, 2.50 and 2.00 respectively, suggesting there is still a high dipolar loss induced by SF for Al-doped SiCw [18]. In addition, the spacecharge induced polarization at these interfaces between SiCw and paraffin wax also contribute to the absorption ability of SiC W .…”

“…As all known, compared to the Al-doped SiC equiaxial granules, Al-doped SiCw can construct an interconnect 3D conduction network more easily in the matrix when the SiC loading level is the same. Meanwhile the SiC whiskers prepared under microwave irradiation possess high density stacking faults (SF), resulting in a larger dipolar loss [18].…”

In-situ growth of SiC nanowire arrays on carbon fibers and their microwave absorption properties

“…The dielectric loss is mainly due to polarization. Firstly, a high density of SFs and TBs within SiC nanowires can give birth to the space charge polarizationand relaxation, leading to the enhanced dipole polarization loss[44,45]. Secondly, the high aspect ratio of nanowires is believed to play an important role in the microwave absorption due to the formation of a large amount of interfacial polarization at the interfaces between the…”

The enhanced polarization relaxation and excellent high-temperature dielectric properties of N-doped SiC

“…The enhanced polarization relaxation and excellent high-temperature dielectric properties of N-doped SiC Yan-Kun Dou, 1,a) Jing-Bo Li, 1,b) Xiao-Yong Fang, 2,c) Hai-Bo Jin, 1,d) and Mao-Sheng Cao 1 The dielectric properties and microwave attenuation performance of N-doped SiC have been evaluated in 8. 2-12.4 GHz in the temperature range of 293-673 K. The N doping dramatically improves the microwave absorption capability of SiC.…”

“…Electromagnetic wave (EMW) absorbing materials have been attracting worldwide attention, with the rapid development of wireless communications and high-frequency circuit devices. [1][2][3] For some microwave absorbing materials, especially carbon nanotubes and ferromagnetic materials, the susceptibility to oxidation at high temperature restricts their wide applications. 4,5 The silicon carbide (SiC) is considered to be one of the important candidates of microwave absorbing materials at high temperature, 6-9 especially nano-sized particles of SiC, due to its high strength, hardness, good corrosion, thermal stability, low weight, and good resistance oxidation.…”