Enhancing Defect-Induced Dipole Polarization Strategy of SiC@MoO_(3)Nanocomposite Towards Electromagnetic Wave Absorption

Defect engineering in transition metal oxides semiconductors(TMOs)is attracting considerable interest due to its potential to enhance conductivity by intentionally introducing defects that modulate the electronic structures of the materials.However,achieving a comprehensive understanding of the relationship between micro-structures and electromagnetic wave absorption capabilities remains elusive,posing a substantial challenge to the advancement of TMOs absorbers.The current research describes a process for the deposition of a MoO_(3)layer onto SiC nanowires,achieved via electro-deposition followed by high-temperature calcination.Subsequently,intentional creation of oxygen vacancies within the MoO_(3)layer was carried out,facilitating the precise adjustment of electromagnetic properties to enhance the microwave absorption performance of the material.Remarkably,the SiC@MO-t4 sample exhibited an excellent minimum reflection loss of-50.49 dB at a matching thickness of 1.27 mm.Furthermore,the SiC@MO-t6 sample exhibited an effective absorption bandwidth of 8.72 GHz with a thickness of 2.81 mm,comprehensively covering the entire Ku band.These results not only highlight the pivotal role of defect engineering in the nuanced adjustment of electromagnetic properties but also provide valuable insight for the application of defect engineering methods in broadening the spectrum of electromagnetic wave absor ption effectiveness.SiC@MO-t samples with varying concentrations of oxygen vacancies were prepared through in-situ etching of the SiC@MoO_(3)nanocomposite.The presence of oxygen vacancies plays a crucial role in adjusting the band gap and local electron distribution,which in turn enhances conductivity loss and induced polarization loss capacity.This finding reveals a novel strategy for improving the absorption properties of electromagnetic waves through defect engineering.

Construction of NiCeO_(x) nanosheets-skeleton cross-linked by carbon nanotubes networks for efficient electromagnetic wave absorption

In this work,two-dimensional NiCeOx nanosheet-modified carbon nanotubes(CNTs)composites were prepared by a hydrothermal method.NiCeOx with different morphologies can be formed by adjusting the addition ratio of nickel salt and cerium salt,and the introduction of CNTs in the subsequent synthesis process can effectively prevent the aggregation of NiCeOx nanosheets.Microstructural studies show that hexagonal NiCeOx nanosheets with a size of 100 nm are uniformly intertwined with CNTs.When applied to the attenuation of electromagnetic waves,NiCeOx/CNTs composites exhibit better electromagnetic wave(EMW)absorption performance than pure CNTs and NiCeOx nanosheets due to improved impedance matching and multiple polarization relaxation.At the matching thickness of 1.9 mm,the composite exhibits a minimum reflection loss(RL_(min))of–53.2 dB and an effective absorption bandwidth(RL<–10 dB)of 5.04 GHz with a thickness of 2.3 mm.These results indicate that the as-prepared NiCeOx/CNTs composites have excellent EMW absorption performance and are expected to be a candidate material for EMW absorption.

3D carbon network supported porous SiOC ceramics with enhanced microwave absorption properties

Porous SiOC ceramic was successfully prepared by pyrolysis of dimethylsilicone oil,silane coupling agent and melamine foam.The microwave absorbing properties of porous SiOC were studied for the first time.At the matching layer thickness of 3.0 mm,the paraffin-based composite with porous SiOC displays a minimum reflection coefficient(RC)of-39.13 d B(11.76 GHz)and an effective absorption bandwidth(EAB)of 4.64 GHz which are much larger than that of paraffin-based composite with ordinary SiOC.It is found that the porous structure of SiOC is crucial to achieve its high microwave absorption performance by improving both the polarization loss and conduction loss.The enhanced polarization loss is originated from the dipole polarization and interfacial polarization,while the improvement of conduction loss is attributed to the carbon skeleton of porous SiOC.These results indicate that porous SiOC ceramic is a promising candidate for high-performance ceramic-based microwave absorbing materials.