http://dspace.nbuv.gov.ua:80/handle/123456789/132699 2026-04-18T06:29:44Z http://dspace.nbuv.gov.ua:80/handle/123456789/136474 Electrophysical properties of polymer composites penton-silver iodide system in 8-12 GHz frequency region Rokitsky, M.A.; Gorbyk, P.P.; Levandovsky, V.V.; Makhno, S.M.; Kondratenko, O.V.; Shut, N.I. The heat field influence on electrophysical properties of polymer composites of the penton — dispersed silver iodide (Agl) system at volume filling from 0 to 100 % have been studied in 8-12 GHz frequency range. It has been shown that both real (ξ') and imaginary (ξ") complex dielectric permittivity components below the temperature of Agl dielectric-ionic phase transition (Tc = 420 K) depend on the content of the system components, and the imaginary component depends also on the polymer supermolecular structure. After Agl transition into ionic state, a percolation transition is observed in concentration dependences at critical percolation threshold about 30 vol.% filler content and extreme maxima about C = 50%. The ξ' and ξ" values exceed almost in wice the corresponding Agl characteristics. The results are discussed within the frame structure model. 2007-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/136472 Influence of domain structure on relaxation phenomena in the PZT ceramic Brus, B.; Ilczhuk, J.; Zarycka, A.; Czerwiec, M. The temperature dependences of internal friction in PZT ceramics have been obtained in a wide temperature range from the room temperature to that exceeding the phase transition point from ferroelectric to paraelectric phase. The aim of the study was to describe the influence of domain structure on relaxation phenomena in samples of undoped PZT ceramics and multicomponent ceramics doped with Cd and W–Pb(W₁Cd)O₃–PbZrO₃– PbTiO₃, prepared by the sol-gel method and by solid state reaction, respectively, followed by sintering. Basing on the internal friction measurements, the relaxation phenomena observed in examined ceramics have been described. The relaxation peaks connected with interaction point defects and domain walls and viscoelastic motion of domain walls have been observed in the temperature dependences of internal friction. For all relaxation peaks, the values of activation energy H and pre-exponential factor τ₀ have been calculated. 2007-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/136470 The relaxation phenomena in irradiated PZT type piezoceramics Zachariasz, R.; Ilczuk, J.; Brus, B. The samples of PZT type multi-component piezoceramics Pb₀.₉₇₅Ba₀.₀₁Ca₀.₀₁Sr₀.₀₀₅(Zr₀.₅₂Ti₀.₄₈)O₃ + 1.4 wt.% Bi₂O₃ + 0.3 wt% GeO obtained by hot pressing were shaped as (30x10x0.9) mm3 plane-parallel plates. Some samples were subjected to polarization by low temperature method (T = 423 K, Ep = 30 kV/cm, t = 30 min), and others were γ-irradiated (200 kGy, ⁶⁰Co). For all specimens, temperature dependences of the internal friction Q⁻¹ and Young's modulus E were determined while heating at a rate of 3 K/min. The Q⁻¹(T) curve shows two peaks PR and PT,' located for non-irradiated sample at TR= 380 K, TF = 640 K, respectively. For samples irradiated at 200 kGy dose, the PR peak shifts towards higher temperatures, while PT,' towards lower ones. The values of Young's modulus E are decreased in the area of the PR and PF peaks. At room temperature, the E value is 133 GPa for the non-irradiated sample and 150 GPa for the irradiated one. The relaxation peak PR has been shown to be due to the domain boundary interaction with oxygen vacancies while the PF one is related to the phase transition at the Curie point. 2007-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/136468 The method of optical investigations of the nanostructural diamond-like a-C:N films Kara-Murza, S.V.; Belyaev, B.V.; Gritskih, V.A.; Zhikharev, I.V.; Kortchikova, N.V.; Naumenko, D.A.; Prudnikov, A.M. A complex technique has been proposed for optical investigations of nanostructured diamond-like a—C:N films. To determine the thickness d, refractive index no and extinction coefficient n₀, the refraction ellipsometry at fixed wavelength λ₀ = 632.8 nm with different incidence angles has been used. Proceeding from the n₀, K₀ and d values, the n(λ), K(λ) dependences have been restored basing on the optical transmission curves within the 280-1200 nm range, and, as a consequence, the dependence of the imaginary part of dielectric constant, ξ", on the photon energy near the fundamental absorption edge. The band gap width Eg and the Tauc coefficient B have been determined for the films obtained under various technological conditions and preliminary conclusions have been drawn for the contributions from sp² and sp³ phases depending on those conditions. 2007-01-01T00:00:00Z