Abstract
The microwave absorption properties of Ni/(C, silicides) nanocapsules prepared by an arc discharge method have been studied. The composition and the microstructure of the Ni/(C, silicides) nanocapsules were determined by means of X-ray diffraction, X-ray photoelectric spectroscopy, and transmission electron microscope observations. Silicides, in the forms of SiOx and SiC, mainly exist in the shells of the nanocapsules and result in a large amount of defects at the ‘core/shell’ interfaces as well as in the shells. The complex permittivity and microwave absorption properties of the Ni/(C, silicides) nanocapsules are improved by the doped silicides. Compared with those of Ni/C nanocapsules, the positions of maximum absorption peaks of the Ni/(C, silicides) nanocapsules exhibit large red shifts. An electric dipole model is proposed to explain this red shift phenomenon.
Highlights
Magnetic nanocapsules have attracted increasing attention in the area of electromagnetic wave absorption in the last decades because of their peculiar structural characteristics [1,2,3,4]
Wang et al have reported that changing the thickness of the graphite shell of Ni/C nanocapsules can modulate the effective permittivity. Both carbon and silicon dioxide are widely used as shell materials, in which the former has a layered structure and the latter is a good insulator [5]
In order to determine the surface compositions of the Ni/(C, silicides) nanocapsules, X-ray photoelectron spectroscopy (XPS) spectra were measured after etching times of 0, 10, and 20 s
Summary
Magnetic nanocapsules have attracted increasing attention in the area of electromagnetic wave absorption in the last decades because of their peculiar structural characteristics [1,2,3,4]. Wang et al (unpublished work) have reported that changing the thickness of the graphite shell of Ni/C nanocapsules can modulate the effective permittivity. Both carbon and silicon dioxide are widely used as shell materials, in which the former has a layered structure and the latter is a good insulator [5]. SiO2 can react with carbon at high temperatures to produce semiconducting SiC [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
