Development Of Electromagnetic Technology Research Articles

Microwave absorption enhancement via graphene sheet-guided preparation of flake-like titanium carbide

With the development of electromagnetic technology, there is an urgent need for further research on highly efficient and lightweight microwave absorption materials. Transition metal carbides have drawn tremendous attention due to their strong microwave dissipation ability and perfect stability in extreme environments. However, owing to carburization under high temperatures, synthesizing metal carbides with specified morphology is still a challenge. Here, titanium carbide (TiC) with a flake-like structure was prepared through a carbothermic reduction method guided by two-dimensional graphene sheets. The prepared flake-like TiC sheets show excellent microwave absorption properties in 1–40 GHz compared with TiC spherical particles. A minimum reflection loss (RL) of −57.0 dB at 11.8 and 3.2 GHz effective absorption bandwidth (RL < −10 dB) was achieved. Meanwhile, an optimal RL of −57 dB is also achieved at 35.8 GHz together with an even broader absorption bandwidth from 34.2 to 40 GHz (5.8 GHz in total). This excellent microwave absorption performance is attributed to the flake-like morphology, which dramatically enhances the multiple polarization loss. The method of utilizing graphene sheets as a guide to fabricate flake-like TiC not only illuminates a new strategy for fabricating transition metal carbides with specified morphology but also provides an attractive candidate for microwave absorption applications.

Towards Nuclear Magnetic Resonance μ‐Spectroscopy and μ‐Imaging

AbstractFor Abstract see ChemInform Abstract in Full Text.

Towards nuclear magnetic resonance micro-spectroscopy and micro-imaging.

The first successful experiments demonstrating Nuclear Magnetic Resonance (NMR) were a spin-off from the development of electromagnetic technology and its introduction into civilian life in the late forties. It was soon discovered that NMR spectra held chemically relevant information making it useful as an analytical tool. By introducing a new way of detection, moving away from continuous wave spectroscopy, Fourier Transform NMR helped to overcome sensitivity problems and subsequently opened the way for multi-dimensional spectroscopy. As a result NMR has developed into one of the most powerful analysis techniques with widespread applications. Still sensitivity is a limiting factor in the applicability of NMR. Therefore we witness a renaissance of technique development in magnetic resonance striving to improve its receptiveness. This tutorial review introduces the efforts currently made in miniaturizing inductive detection by designing optimal radio-frequency microcoils. A second approach is to introduce a new way of detecting magnetic resonance signals by means of very sensitive micromechanical force detectors. This shows that the detection limits in terms of absolute sensitivity or imaging resolution are still open to significant improvements.