Enhanced Polarization from Hollow Cube-like ZnSnO₃ Wrapped by Multiwalled Carbon Nanotubes: As a Lightweight and High-Performance Microwave Absorber

Abstract

Polarization and conduction loss play fundamentally important roles in the nonmagnetic microwave absorption process. In this paper, a uniform and monodisperse hollow ZnSnO cube wrapped by multiwalled carbon nanotubes (ZSO@CNTs) was successfully synthesized via facile hydrothermal treatment. A reasonable mechanism related to Ostwald ripening was proposed to design the varied ZSO@CNTs for the special hollow conductive network. Scanning electron microscopy images clearly indicate that reaction temperature is the key factor for the composite structure, which has a significant effect on its electromagnetic properties. Electron holography proves the inhomogeneous distribution of charge density in the ZSO@CNT system, leading to the occurrence of interface polarization. Complex permittivity properties of ZSO@CNT composites under different reaction temperatures were investigated to optimize the morphology that can distinctly enhance microwave absorption performance. The maximum reflection loss that the ZSO@CNT-130 °C composite can reach is -52.1 dB at 13.5 GHz, and the absorption bandwidths range from 11.9 to 15.8 GHz with a thickness as thin as 1.6 mm. Adjusting the simulation thicknesses from 1 to 5 mm, the efficient absorption bandwidth (RL < -10 dB) that the ZSO@CNT composite could reach was 14.16 GHz (88.8% of 2-18 GHz). The excellent microwave absorption performance may be attributed to the synergistic effects of polarization, conduction loss, and special hollow cage structure. It is proposed that the specially controlled structure could provide an effective path for achieving a high-performance microwave absorber.

Oriented Polarization Tuning Broadband Absorption from Flexible Hierarchical ZnO Arrays Vertically Supported on Carbon Cloth

“…On the basis of phase reconstructive images (Figure b,c,f,i), obviously, there are both negative and positive carrier distribution regions around the ZnO interface, confirming a polarization dipole (Figure d). Positive charge accumulates around the externals interface and cavity surfaces, while negative charge gathers on the corresponding internal regions, leading to an intensive interfacial polarization . By magnifying the polarization zone (Figure g,j), we can see that the fluctuation degree of charge density at the internal interface becomes stronger than that of the external interface, which indicates that the internal cavity interface space has a stronger influence on the dielectric loss (Figure S5a,c, Supporting Information).…”

Galvanic Replacement Reaction Involving Core–Shell Magnetic Chains and Orientation‐Tunable Microwave Absorption Properties

“…[69] Stimulated by an incident EM wave with alternating vector direction in a short period of time, both the natural dipole moment and electric field in numerous hetero-joints could re-align to a confined orientation, thus generating macroscopic polarization intensity. [70] In this process, it is evident that both the interfacial polarization and spatial charge polarization can dissipate the energy of the penetrated EM wave.…”

Enhanced Microwave Absorption Performance from Magnetic Coupling of Magnetic Nanoparticles Suspended within Hierarchically Tubular Composite

“…Among the reported carbonaceous composites, 1D absorbents have gained a growing attention, because their high anisotropy facilitates the enhancement of dielectric loss ability . For instance, CNT/Fe 3 O 4 , carbon fiber/Co 3 O 4 /nitrogen‐doped carbon, and carbon fiber/ferromagnetic metal composites have acquired the optimized MA performance through combining superiorities of multiple components and 1D structure 5a,8.…”