Electromagnetic wave absorption properties of magnetic particle-doped SiCN (C) composite ceramics

Research on Percolation Threshold of Broadband Electromagnetic Wave Absorbing SiCN (MWCNTs) Composite Ceramics

“…2b is the Raman spectrum of each sample. The clear D peak and G peak in each sample indicated the existence of free carbon in ceramics, which provided media for electron transport and transition [4]. The defect level of carbon-containing materials can be characterized by the intensity ratio of D peak to G peak (I D /I G ), and a larger ratio of I D /I G demonstrated a higher defect level in the material [2].…”

“…5 10-5). The existence of eddy carbon provides a channel for electron transport and transition, and is also the basis for SiCN ceramic matrix to have certain dielectric loss properties [3,4,18]. Fig.…”

“…Hence, complex permeability parameters of samples are not elaborated here. and each semicircle represents a polarization process that follows the Debye relaxation [4,21]. Fig.…”

“…9b, obvious Cole semicircles appeared in sample 10 compared with sample 0, indicating that the addition of MWCNTs provided abundant interfacial polarization for composite ceramics [30,31]. Cole semicircles were mainly distributed at higher frequencies, indicating that interfacial polarization is the main mechanism of dielectric loss at higher frequencies [4]. In the lower frequencies, the ε″-ε' image of sample 10 presented nearly as a straight line, indicating that conduction loss is the main way to dissipate electric energy at lower frequencies [22,23,32].…”

“…In recent years, considerable attention has been paid to SiCN ceramics in the field of EMW absorbers [3]. Relevant studies have shown that SiCN ceramics can withstand a high temperature of 1100 ℃ in air atmosphere without changes in morphology and structure, and this excellent high temperature resistance and oxidation resistance is absent in polyester-based and carbon-based EMW absorbers [4]. Beyond that, the carbon nanodomain contained in it ensures a good dielectric loss performance and a certain EMW absorption capacity (SiCN ceramics with thickness of 8 mm can absorb about 90% EMW in the range of 6~16 GHz.…”