DEEPER UNDERSTANDING OF COBALT-DOPED SIC NANOWIRES AS EXCELLENT ELECTROMAGNETIC WAVE ABSORBERS

摘要

Doping is a facile and effective technique that plays a key role in the function of many semiconductor materials. Unraveling the regulatory mechanism of doping can offer useful guidance for the design of the material structure and fabricating novel functional composites invalid in pure phase structures, which extents their applications in catalysts, light emitting devices, and environmental protection. Especially, transition metal doping related to the spin and charge introduces foreign states to the electronic structures in the host materials and endows the composites with intriguing properties. However, most of the reported papers are limited on the fabrication of the doped composites with enhanced performance. Little progress has been made to clarify the underlying mechanism for those improvements. Herein, Co-doped SiC nanowires with different Co contents were successfully fabricated by a simple carbothermal reduction method. The Co-doped SiC nanowires were characterized in terms of microstructure, electronic structure, and electromagnetic (EM) parameters to study the effects of doping on enhancing the EM wave absorption ability. Both the microstructure analysis and density functional theory calculations indicated that the incorporation of Co into SiC nanowires inhibited the formation of defective structures but increased their conductivity. Thus, the improved electronic transportation ability was dominant in enhancing the dielectric loss. The Co dopants also imparted the Co-doped SiC nanowires with magnetic property, which could generate magnetic resonance to attenuate EM wave and achieve superior impedance matching. The induced synergistic effects between Co dopants and SiC nanowires endowed Co-doped SiC nanowires with excellent EM wave absorption ability. Their minimum reflection loss was -50 dB, and the effective absorption bandwidth was up to 4.0 GHz at 1.5 mm sample thickness. Therefore, the fabricated Co-doped SiC nanowires are potential candidates for high-efficiency EM wave absorption materials. The findings of this research provide a guideline for other doped functional composites.