K. V. Dorozhkin

Iron-filled multi-walled carbon nanotubes for terahertz applications: effects of interfacial polarization, screening and anisotropy

Interface interactions in multicomponent nanoparticles can affect electromagnetic properties of an absorbing system. In this work, we investigate the electromagnetic response of multi-walled carbon nanotubes (MWCNTs) filled with iron-containing nanoparticles (ICNs) in the terahertz frequency range. MWCNTs with different iron content have been synthesized by aerosol-assisted catalytic chemical vapour deposition method from toluene containing a certain quantity of ferrocene used as a catalyst. According to the x-ray diffraction analysis, encapsulated ICNs were mainly in the form of iron carbide. Thin composite films were prepared from the iron-filled MWCNTs and polymethylmethacrylate (PMMA) by casting and stretching methods. The composites showed an enhanced permittivity and anisotropy in the transmittance spectra when iron content increased. This behaviour was related to the mechanism based on electrical conductivity and polarization of ICNs and ICN/MWCNT interfaces. Since terahertz field penetrates inside MWCNTs, the filling of their cavities can be a way of varying the electromagnetic properties of MWCNT-containing composites.

Research of a possibility of resonator diagnostics of thin filamentary objects in a low part of the terahertz frequency band

The method of excitement of the open resonator by the narrow slot on a reflector formed by the waveguide with the highest modes transmitted was experimentally approved. The spectra of such resonator in the range of the frequencies of 85 GHz–110 GHz were received. It is shown that modes with azimuthal variations of the field were most effectively exited. Transformations of spectra by thin dielectric cylinders were researched. A number of parameters of the open resonator, effective in schemes of resonator diagnostics of filamentary objects with small own losses were found.

Electromagnetic response of the three-layer construction on the basis of barium hexaferrite and a foam glass

This paper contains results of study of the frequency dependence of reflection coefficient of the ceramic surface coated with the construction consisting of following layers: metal, composite on the basis of ferrite with hexagonal structure, and foam glass. It is shown that foam glass layer reduces significantly the reflecting characteristics of the construction.

Quasi-optical 2D system for non-contact non-destructive testing of defects in natural and artificial crystals

The results of development the automated system of two-dimensional diagnostics of defects of crystalline materials are presented. Used technology imaging. The structural scheme of the system is given, its main blocks are indicated, the approbation process is described, the software of the system is described.

Spectra of electromagnetic parameters of multicomponent radioabsorbing material at frequency range 20 Hz–100 GHz

Measurements results of spectra of permittivity, permeability, reflection, transmission and absorption coefficients of polymer composite with nanosized filler are presented. Material absorbs electromagnetic waves intensively at superhigh and extremely high frequencies.

The foam-glass material for a radio frequency echoless chambers

The conducted experiment of foam glass modification by carbon nanotubes shows increased radio absorbing properties in comparison with a foam glass without additives. Addition of carbon nanodimensional tubes in number of 1,5 wt.% increases a tangent of dielectric losses angle by 2,5 times. The coefficient of electromagnetic radiation absorption in the range of frequencies of 120 - 260 GHz increases for a foam glass with carbon nanotubes (1,5 wt. %) twice in comparison with a foam glass without additives. The foam glass modified by carbon nanotubes is recommended as the effective radio absorbing material for the device of anechoic cameras. This material is fire safety, nonflammable, environmentally friendly, rather light-weight.