Controllable synthesis of defective carbon nanotubes/Sc2Si2O7 ceramic with adjustable dielectric properties for broadband high-performance microwave absorption. (June 2019)

• Record Type: Journal Article
• Authors: Wei, Hanjun; Yin, Xiaowei; Li, Xin; Li, Minghang; Dang, Xiaolin; Zhang, Litong; Cheng, Laifei
• Is Part Of: Carbon. Volume 147(2019)
• Page Start: 276
• Page End: 283
• Publication Date: 2019-06
• Subjects: Defects -- Density functional theory (DFT) -- Microwave absorption properties -- CNTs/Sc2Si2O7 ceramics; Carbon -- Periodicals; Carbone -- Périodiques; Koolstof; Toepassingen; Electronic journals; 546.681
• DOI: 10.1016/j.carbon.2019.03.008
• Languages: English
• ISSNs: 0008-6223

Abstract

Abstract: High-performance carbon nanotubes (CNTs) with adjustable electro-conductivity have been widely used as electromagnetic (EM) waves absorption materials to achieve stealth of weapons and equipment. Chemical vapor deposition technology is used for the simple preparation of CNTs on porous Sc2 Si2 O7 matrix. As expected, well-matched impedance and EM dissipation of CNTs/Sc2 Si2 O7 ceramics are synthesized. Curls of CNTs formed a three-dimensional network structure and large amounts of interfaces, resulting in multiple reflections and scattering of EM waves. The defect concentrations can be optimized by tuning reaction times. The existing defects will produce dipole polarization and affect the band gap of CNTs as well. Using density functional theory as first principle calculations, we calculate and simulate the relationship between band gap and vacancy-defects of CNTs. The results show that the appropriate contents of vacancy-defects will increase the band gap of CNTs, which regulate the conductivity loss of CNTs/Sc2 Si2 O7 . Hence, the excellent microwave absorption performance of CNTs/Sc2 Si2 O7 (loading content of 1.56 wt%) is RCmin of −33.5 dB at the thickness of 2.85 mm, achieving an effective absorbing bandwidth of 4.2 GHz covering the whole X-band. The exploration results provide a useful reference to EM wave absorption materials with strong absorption, wide bandwidth and thin thickness. Graphical abstract: Image 102