Dmitriy Afanasyev

Prof. Dmitriy Afanasyev


Research Focus & Metrics

Academic Career Length

16Years (2011-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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31 August 2019 in Applied Physics B
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NINiazbek Ibrayev
Niazbek Ibrayev
AIAlexander Ishchenko
Alexander Ishchenko
DADmitriy Afanasyev
Dmitriy Afanasyev
NZNazerke Zhumabay
Nazerke Zhumabay

8 April 2016 in Russian Journal of Physical Chemistry A
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DADmitriy Afanasyev
Dmitriy Afanasyev
NINiyazbek Ibrayev
Niyazbek Ibrayev
TSTimur Serikov
Timur Serikov
AZA. K. Zeinidenov
A. K. Zeinidenov

6 September 2023 in Crystals
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VKValeriy Kalytka
Valeriy Kalytka
AМAli Меkhtiyev
Ali Меkhtiyev
YNYelena Neshina
Yelena Neshina
AAAliya Alkina
Aliya Alkina
RARaushan Aimagambetova
Raushan Aimagambetova
YSYelena Senina
Yelena Senina
The quantum statistical properties of the proton subsystem in hydrogen-bonded crystals (HBC) are investigated. Based on the non-stationary Liouville operator equation (taking into account a number of assumptions established in the experiment), a quantum kinetic equation is constructed for the ensemble of non-interacting protons (an ideal proton gas) moving in the crystal potential image perturbed by the external electric field. The balanced density matrix for the unperturbed proton subsystem is constructed using the quantum canonical Gibbs distribution, and the non-balanced density matrix is calculated from the solutions of the nonlinear quantum kinetic equation by methods in linear approximation of perturbation theory for the blocking electrode model. Full quantum mechanical averaging of the polarization operator makes it possible to study the theoretical frequency-temperature spectra of the complex dielectric permittivity (CDP) calculated using quantum relaxation parameters that differ significantly from their semiclassical counterparts. A scheme is presented for an analytical study of the dielectric loss tangent in the region of quantum nonlinear relaxation in HBC. The results obtained in the given paper are of scientific interest in developing the theoretical foundations of proton conduction processes in energy-independent memory elements (with anomalously high residual polarization) based on thin films of ferroelectric materials in the ultralow temperature range (1–10 K). The theoretical results obtained have a direct application to the study of the tunneling mechanisms of spontaneous polarization in ferroelectric HBC with a rectangular hysteresis loop, in particular in crystals of potassium dideutrophosphate (KDP), widely used in nonlinear optics and laser technology. The quantum properties of proton relaxation in HBC can be applied in the future to the study of solid-state electrolytes with high proton conductivity for hydrogen energy, capacitor technology (superionics, varicodes), and elements of MIS and MSM structures in the development of resonant tunnel diodes for microelectronics and computer technology.

19 August 2024 in Ceramics
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GAGulnur Alpyssova
Gulnur Alpyssova
Victor Mikhailovich LisitsynVictor Mikhailovich Lisitsyn
Victor Mikhailovich Lisitsyn
ZBZhanara Kanatovna Bakiyeva
Zhanara Kanatovna Bakiyeva
ICIvan Chakin
Ivan Chakin
EKEkaterina Kaneva
Ekaterina Kaneva
STSerik Tuleuov
Serik Tuleuov
This paper presents the results of a study on the morphology, structure, and luminescent properties of ceramics synthesized in the radiation field of MeWO4 compositions (where Me is Mg, Ca, and Zn). The synthesis of ceramics was carried out by the direct action of the electron flux on an initial mixture of powders of the given stoichiometric composition. WO3, ZnO, MgO, and CaO powders with particle sizes in the range of 1–50 microns were used for the synthesis of the samples. It was found that the yield of the radiation synthesis reaction (the ratio of the mass of the sample and the charge used), when treated with an electron flux with an energy of 1.4 MeV and a flux power density of 15–18 kW/cm2, was in the range of 75–99%. The synthesis of all compositions was carried out under the same radiation treatment modes, although the melting temperatures of the starting materials varied significantly and ranged from 1473 °C (WO3) to 2825 °C (MgO). The study of the ceramic structure showed that under the radiation effect of powerful radiation fluxes on the charge, a crystalline phase of the appropriate composition formed, regardless of the synthesis modes. The results of XRD studies show that during the radiation treatment of the charge, ceramics are formed mainly with the crystalline phases ZnWO4, MgWO4, and CaWO4. These resulting MeWO4 ceramics can be used for the same purposes as crystals. Photoluminescence (PL) and cathodoluminescence (CL) were studied under excitation using stationary ultraviolet radiation and nanosecond pulses of electron flux. In general, the PL and CL of synthesized ceramic samples ZnWO4, MgWO4, and CaWO4 showed that their luminescent properties are similar to those of luminescence in corresponding crystalline materials. This indicates the formation of a crystalline phase in synthesized ceramic samples.

25 January 2013 in Optics and Spectroscopy
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NIN. Kh. Ibrayev
N. Kh. Ibrayev
DADmitriy Afanasyev
Dmitriy Afanasyev
AIA. A. Ishchenko
A. A. Ishchenko
NDN. A. Davidenko
N. A. Davidenko
The spectral and luminescent properties of film composites based on photoconductive poly-N-epoxipropylcarbazole and nonphotoconductive polyvinylbutyral with admixtures of cationic and anionic polymethine dyes, as well as the effect of an external magnetic field on these properties, are studied. It is found that the magnetic field affects the intensity and kinetics of the delayed fluorescence and recombination luminescence of the cationic dye in photoconductive films. This is explained by specific features of photogeneration of charge pairs, namely, by the participation of the singlet and triplet excited states of dye molecules in this process, as well as by the singlet-triplet conversion in dye molecules and photogenerated charge pairs.

1 June 2012 in Chemical Physics Letters
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NIN.KH. Ibrayev
N.KH. Ibrayev
DADmitriy Afanasyev
Dmitriy Afanasyev