Browsing by Author "Kovalchuk, T. M."
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- Effect of modification of nonwoven textiles with biochar and multi-walled carbon nanotubes on their dielectric propertiesPublication . Kovalchuk, O. V.; Prochazkova, J.; Kolanowska, A.; Mariano, José; Boncel, S.; Zolochevska, K.; Kovalchuk, T. M.; Kopčanský, P.; Safarik, I.Dielectric properties of native nonwoven textile as well as textile with bound biochar and multi-walled carbon nanotubes in the frequency range of 10 to 5·105 Hz and at the temperatures of 30 to 60 °C have been investigated. The capacity of native nonwoven textile has been shown to decrease with the temperature according to the Arrhenius law. The activation energy of the temperature dependence of the capacity has been estimated to be 0.09 eV. It has been demonstrated that regardless of the temperature, the frequency dependence of the resistance of the nonwoven textile can be described by two exponential functions. In the presence of bound biochar and multi-walled carbon nanotubes in the nonwoven textile, the conductivity current was 4 orders of magnitude greater than the bias current and increased with the temperature according to the Arrhenius law. The activation energy of the temperature dependence of the inverse resistance (an analogue of the conductivity for homogeneous samples with the same dimensions) has been estimated to be 0.19 eV for the samples with multi-walled carbon nanotubes and 0.62 eV for the samples with bound biochar.
- Saturation effect for dependence of the electrical conductivity of planar oriented nematic liquid crystal 6CB on the concentration of Cu7PS6 nanoparticlesPublication . Kovalchuk, O. V.; Studenyak, I. P.; Izai, V. Yu; Rybak, S. O.; Pogodin, A. I.; Kopčanský, P.; Timko, M.; Gdovinova, V.; Mariano, José; Kovalchuk, T. M.The influence of Cu7PS6 nanoparticles with the average size 117 nm on the dielectric properties of planar oriented nematic liquid crystal 6CB has been investigated within the frequency range 10(1) ...10(6) Hz and at the temperature 293 K. It has been shown that when changing the concentration of nanoparticles within the range 0 to 1 wt.%, the conductivity of the liquid crystal changes stronger than its dielectric permittivity. It has been shown that the electrical conductivity increases monotonously with increasing the concentration of nanoparticles. However, for this dependence a saturation effect is observed. The mechanism of this effect was proposed.