33 results on '"Dauletbekova, Alma"'
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2. Color Centers in BaFBr Crystals: Experimental Study and Theoretical Modeling.
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Inerbaev, Talgat, Akilbekov, Abdirash, Kenbayev, Daurzhan, Dauletbekova, Alma, Shalaev, Alexey, Polisadova, Elena, Konuhova, Marina, Piskunov, Sergei, and Popov, Anatoli I.
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LIGHT absorption ,ELECTRON transitions ,CRYSTALS ,CRYSTAL defects ,OPTICAL properties - Abstract
This study presents theoretical and experimental investigations into the electron and hole color centers in BaFBr crystals, characterizing their electronic and optical properties. Stoichiometric BaFBr crystals grown by the Steber method were used in the experiments. Radiation defects in BaFBr crystals were created by irradiation with 147 MeV
84 Kr ions with up to fluences of 1010 –1014 ions/cm2 . The formation of electron color centers (F(F− ), F2 (F− ), F2 (Br− )) and hole aggregates was experimentally established by optical absorption spectroscopy. Performed measurements are compared with theoretical calculations. It allows us to determine the electron transition mechanisms and investigate the processes involved in photoluminescence emission in Eu-doped BaFBr materials to enhance the understanding of the fundamental electronic structure and properties of electron and hole color centers formed in BaFBr crystals. [ABSTRACT FROM AUTHOR]- Published
- 2024
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3. The Effect of 147 MeV 84 Kr and 24.5 MeV 14 N Ions Irradiation on the Optical Absorption, Luminescence, Raman Spectra and Surface of BaFBr Crystals.
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Akilbekov, Abdirash, Kenbayev, Daurzhan, Dauletbekova, Alma, Shalaev, Alexey, Akylbekova, Aiman, Aralbayeva, Gulnara, Baimukhanov, Zein, Baizhumanov, Muratbek, Elsts, Edgars, and Popov, Anatoli I.
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LIGHT absorption ,RAMAN spectroscopy ,NEUTRON irradiation ,CRYSTAL surfaces ,LUMINESCENCE ,SPECTRUM analysis ,RUTHERFORD backscattering spectrometry ,PHOTOLUMINESCENCE measurement - Abstract
Today, BaFBr crystals activated by europium ions are used as detectors that store absorbed energy in metastable centers. In these materials, the image created by X-ray irradiation remains stable in the dark for long periods at room temperature. As a result, memory image plates are created, and they are extended to other types of ionizing radiation as well. Despite significant progress towards X-ray storage and readout of information, the mechanisms of these processes have not been fully identified to date, which has hindered the efficiency of this class of phosphors. In this study, using photoluminescence (PL), optical absorption (OA), Raman spectroscopy (RS), and atomic force microscopy (AFM), the luminescence of oxygen vacancy defects to BaFBr crystals irradiated with 147 MeV
84 Kr and 24.5 MeV14 N ions at 300 K to fluences (1010 –1014 ) ion/cm2 was investigated. BaFBr crystals were grown by the Shteber method on a special device. Energy-dispersive X-ray spectroscopy (EDX) analysis revealed the presence of Ba, Br, F, and O. The effect of oxygen impurities present in the studied crystals was considered. The analysis of the complex PL band, depending on the fluence and type of ions, showed the formation of three types of oxygen vacancy defects. Macrodefects (tracks) and aggregates significantly influence the luminescence of oxygen vacancy defects. The creation of hillocks and tracks in BaFBr crystals irradiated with 147 MeV84 Kr ions is shown for the first time. Raman spectra analysis confirmed that BaFBr crystals were amorphized by 147 MeV84 Kr ions due to track overlap, in contrast to samples irradiated with 24.5 MeV14 N ions. Raman and absorption spectra demonstrated the formation of hole and electron aggregate centers upon swift heavy ions irradiation. [ABSTRACT FROM AUTHOR]- Published
- 2024
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4. Electronic Structure of Mg-, Si-, and Zn-Doped SnO 2 Nanowires: Predictions from First Principles.
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Platonenko, Alexander, Piskunov, Sergei, Yang, Thomas C.-K., Juodkazyte, Jurga, Isakoviča, Inta, Popov, Anatoli I., Junisbekova, Diana, Baimukhanov, Zein, and Dauletbekova, Alma
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NANOWIRES ,STANNIC oxide ,ELECTRONIC structure ,ATOMIC orbitals ,DENSITY functional theory ,BAND gaps - Abstract
We investigated the electronic structure of Mg-, Si-, and Zn-doped four-faceted [001]- and [110]-oriented SnO
2 nanowires using first-principles calculations based on the linear combination of atomic orbitals (LCAO) method. This approach, employing atomic-centered Gaussian-type functions as a basis set, was combined with hybrid density functional theory (DFT). Our results show qualitative agreement in predicting the formation of stable point defects due to atom substitutions on the surface of the SnO2 nanowire. Doping induces substantial atomic relaxation in the nanowires, changes in the covalency of the dopant–oxygen bond, and additional charge redistribution between the dopant and nanowire. Furthermore, our calculations reveal a narrowing of the band gap resulting from the emergence of midgap states induced by the incorporated defects. This study provides insights into the altered electronic properties caused by Mg, Si, and Zn doping, contributing to the further design of SnO2 nanowires for advanced electronic, optoelectronic, photovoltaic, and photocatalytic applications. [ABSTRACT FROM AUTHOR]- Published
- 2024
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5. Luminescence Properties of ZrO 2 : Ti Ceramics Irradiated with Electrons and High-Energy Xe Ions.
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Dauletbekova, Alma, Zvonarev, Sergey, Nikiforov, Sergey, Akilbekov, Abdirash, Shtang, Tatiana, Karavannova, Natalia, Akylbekova, Aiman, Ishchenko, Alexey, Akhmetova-Abdik, Gulzhanat, Baymukhanov, Zein, Aralbayeva, Gulnara, Baubekova, Guldar, and Popov, Anatoli I.
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LUMINESCENCE , *IRRADIATION , *TITANIUM powder , *ELECTRONS , *CERAMICS , *THERMOLUMINESCENCE - Abstract
Samples of ZrO2 ceramics with different concentrations of impurity titanium ions were synthesized by mixing zirconium and titanium oxide powders in different mass ratios. The X-ray diffraction analysis was used to determine the phase composition, lattice parameters, and crystallite size of the ceramics with varying dopant concentrations. Upon irradiation of the samples with 220 MeV Xe ions to a fluence of 1010 ions/cm2, a decrease in the intensity of the pulsed cathodoluminescence band at 2.5 eV was observed. Additionally, ion irradiation resulted in the emergence of a new thermoluminescence peak at 450–650 K attributed to radiation-induced traps of charge carriers. Further analysis revealed that the thermoluminescence curves of samples irradiated with electrons and ions comprise a superposition of several elementary peaks. Notably, a complex non-monotonic dependence of cathodo- and thermoluminescence intensity on titanium concentration was observed, suggesting the influence of concentration quenching and the presence of tunneling transitions. [ABSTRACT FROM AUTHOR]
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- 2024
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6. Synthesis of Orthorhombic Tin Dioxide Nanowires in Track Templates.
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Baimukhanov, Zein, Dauletbekova, Alma, Junisbekova, Diana, Kalytka, Valeriy, Akilbekov, Abdirash, Akylbekova, Aiman, Baubekova, Guldar, Aralbayeva, Gulnara, Bazarbek, Assyl-Dastan, Usseinov, Abay, and Popov, Anatoli I.
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NANOWIRES , *CURRENT-voltage characteristics , *PARTICLE tracks (Nuclear physics) , *CRYSTAL structure - Abstract
Electrochemical deposition into a prepared SiO2/Si-p ion track template was used to make orthorhombic SnO2 vertical nanowires (NWs) for this study. As a result, a SnO2-NWs/SiO2/Si nanoheterostructure with an orthorhombic crystal structure of SnO2 nanowires was obtained. Photoluminescence excited by light with a wavelength of 240 nm has a low intensity, arising mainly due to defects such as oxygen vacancies and interstitial tin or tin with damaged bonds. The current–voltage characteristic measurement showed that the SnO2-NWs/SiO2/Si nanoheterostructure made this way has many p-n junctions. [ABSTRACT FROM AUTHOR]
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- 2024
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7. Ab Initio Study on the Vibrational and Electronic Properties of Radiation-Induced Defects in Potassium Bromide.
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Platonenko, Alexander, Pankratov, Vladimir, Kotomin, Eugene A., Dauletbekova, Alma, and Popov, Anatoli I.
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POTASSIUM bromide ,ALKALI metal halides ,IONS ,CRYSTAL defects ,QUANTUM computing ,ION traps - Abstract
The vibrational and electronic properties of several basic radiation defects in potassium bromide are computed at the quantum mechanical level using a periodic supercell approach based on hybrid functionals, an all-electron Gaussian-type basis set, and the Crystalcomputer code. The exciton energy in alkali halides is sufficient to create lattice defects, such as F–H Frenkel defect pairs, resulting in a relatively high concentration of single defects and their complexes. Here, we consider eight defects: the electronic F + - and F-centers (bromine vacancy without and with trapped electrons) and their dimers; hole H-center (neutral bromine atom forming the dumbbell ion with a regular B r − ion.); V K -center ( B r 2 − molecular ion consisting of a hole and two regular ions); and two complex B r 3 − defects, combinations of several simple defects. The local geometry and the charge- and spin-density distributions of all defects are analyzed. Every defect shows its characteristic features in Raman spectra, and their comparison with available experimental data is discussed. [ABSTRACT FROM AUTHOR]
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- 2024
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8. Structure, electrical properties and luminescence of ZnO nanocrystals deposited in SiO2/Si track templates
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Giniyatova, Sholpan, Dauletbekova, Alma, Baimukhanov, Zein, Vlasukova, Liudmila, Akilbekov, Abdirash, Usseinov, Abay, Kozlovskiy, Artem, Akylbekovа, Aiman, Seitbayev, Aibek, and Karipbayev, Zhakyp
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- 2019
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9. Unveiling the Structural and Optical Properties of MgAl 2 O 4 Single Crystals Irradiated by Swift Heavy Ions.
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Akilbekov, Abdirash, Kiryakov, Arseny, Dauletbekova, Alma, Aralbayeva, Gulnara, Akylbekova, Aiman, and Ospanova, Zhulduz
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HEAVY ions ,OPTICAL properties ,SINGLE crystals ,EXCITATION spectrum ,ION energy ,RAMAN scattering - Abstract
A synthetic single crystal of magnesium-aluminate spinel was irradiated perpendicularly to the (111) plane with swift heavy xenon ions with an energy of 220 MeV. The modified layer was attested based on Raman scattering spectra recorded while focusing on the surface. A decrease in surface crystallinity was observed, reflected in the changes in fundamental optical characteristics such as the band gap and the energies of static and dynamic disorder. In this study, we demonstrate, along with the modification of optical characteristics and the formation of a disordered layer, the creation of new optically active centers. The luminescent properties of these centers were analyzed. The effect of temperature flare-up in the 3.4 eV band of the excitation spectrum was determined. The low sensitivity of Cr
3+ luminescence to SHI is demonstrated. [ABSTRACT FROM AUTHOR]- Published
- 2024
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10. Thermoluminescent and Dosimetric Properties of Zirconium Dioxide Ceramics Irradiated with High Doses of Pulsed Electron Beam.
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Nikiforov, Sergey, Dauletbekova, Alma, Gerasimov, Maksim, Kasatkina, Yana, Denisova, Olga, Lisitsyn, Viktor, Golkovski, Mikhail, Akylbekova, Aiman, Bazarbek, Assyl-Dastan, Akilbekov, Abdirash, and Popov, Anatoli I.
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ZIRCONIUM oxide ,ELECTRON beams ,CERAMICS ,ELECTRIC furnaces ,DIFFRACTION patterns ,POWER density - Abstract
Thermoluminescent (TL) properties of monoclinic zirconium dioxide ceramics were studied in order to assess the possibility of their use for measuring high doses (on the order of kGy) of pulsed electron beams (130 keV). Two types of samples were used: those synthesized by sintering in an electric furnace at T = 700–1700 °C and those synthesized in a flow of high-energy electrons (1.4 MeV) with a high power density. Analysis of the X-ray diffraction patterns using the Scherrer method revealed that annealing of ceramics of the first type at T > 1000 °C leads to a significant increase in the size of crystallites, which correlates with a significant increase in the intensity of the TL peak at 390 K. Type 2 ceramics synthesized by the electron beam method have the maximum TL response. Using the peak shape analysis method, the kinetic parameters of TL (activation energy, frequency factor, and kinetic order) were calculated. This study marks the first instance of establishing the patterns of influence of synthesis conditions and crystallite size on their values. The presence of an intense isolated TL peak, the sublinear nature of most dose dependencies, and negligible fading indicate the promise of the ceramics synthesized in this work for measuring high doses (several to tens of kGy). [ABSTRACT FROM AUTHOR]
- Published
- 2023
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11. Irradiation effect on infrared spectra of LiF:OH crystals: Theoretical modeling
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Inerbaev, Talgat, Dauletbekova, Alma, and Abdrakhmetova, Ainash
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- 2017
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12. Optical Characteristics of MgAl 2 O 4 Single Crystals Irradiated by 220 MeV Xe Ions.
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Akilbekov, Abdirash, Kiryakov, Arseny, Baubekova, Guldar, Aralbayeva, Gulnara, Dauletbekova, Alma, Akylbekova, Aiman, Ospanova, Zhulduz, and Popov, Anatoli I.
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SINGLE crystals ,OPTICAL spectra ,LIGHT absorption ,IONS ,OPTICAL properties ,RAMAN scattering ,VISIBLE spectra - Abstract
In In this study, the optical properties of magnesium-aluminate spinel were examined after being irradiated with 220 MeV Xe ions. The research aimed to simulate the impact of nuclear fuel fission fragments on the material. The following measurements were taken during the experiments: transmission spectra in the IR region (190–7000) nm, optical absorption spectra in the range (1.2–6.5) eV, and Raman spectra were measured along the depth of ion penetration from the surface to 30 µm. A peak with a broad shape at approximately 5.3 eV can be observed in the optical absorption spectrum of irradiated spinel crystals. This band is linked to the electronic color centers of F
+ and F. Meanwhile, the band with a maximum at ~(3–4) eV is attributed to hole color centers. Apart from the typical Raman modes of an unirradiated crystal, additional modes, A1g* (720 cm−1 ), and Eg* (385 cm−1 ), manifested mainly as an asymmetric shoulder of the main Eg mode, are also observed. In addition, the Raman spectroscopy method showed that the greatest disordering of crystallinity occurs in the near-surface layer up to 4 μm thick. At the same time, Raman scattering spectroscopy is sensitive to structural changes almost up to the simulated value of the modified layer, which is an excellent express method for certifying the structural properties of crystals modified by swift heavy ions. [ABSTRACT FROM AUTHOR]- Published
- 2023
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13. The Effect of Fast Kr Ion Irradiation on the Optical Absorption, Luminescence, and Raman Spectra of BaFBr Crystals.
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Akilbekov, Abdirash, Kenbayev, Daurzhan, Dauletbekova, Alma, Polisadova, Elena, Yakovlev, Victor, Karipbayev, Zhakyp, Shalaev, Alexey, Elsts, Edgars, and Popov, Anatoli I.
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LIGHT absorption ,RAMAN spectroscopy ,FAST ions ,ATOMIC force microscopy ,CRYSTALS ,IRRADIATION ,RUTHERFORD backscattering spectrometry - Abstract
In this work, using photoluminescence (PL), optical absorption (OA), Raman spectroscopy (RS), and atomic force microscopy (AFM), the radiation damage of BaFBr crystals irradiated with 147 MeV
84 Kr ions to fluences (1010 –1014 ) cm2 was investigated. The manifestations of the oxygen impurity contained in the studied crystals on the effects associated with ion irradiation are also considered. In unirradiated crystals, the PL spectra exhibited bands related to the oxygen impurity. Moreover, it was found that quenching and a shift of the PL maximum occur, which is due to the fact that, with increasing dose, aggregation of defects occurs. Electronic and hole aggregate color centers appear mainly in the bromide sublattice. A detailed study of the Raman spectra and comparison with the corresponding data for KBr single crystals made it possible to reveal the corresponding manifestations of the Raman modes of complex Br 3 − -type hole centers. [ABSTRACT FROM AUTHOR]- Published
- 2023
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14. Radiation damage caused by swift heavy ions in CaF2 single crystals
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Assylbayev, Ruslan, Akilbekov, Abdirash, Dauletbekova, Alma, Lushchik, Aleksandr, Shablonin, Evgeni, and Vasil'chenko, Evgeni
- Published
- 2016
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15. Influence of Neutron Irradiation Conditions on Maximal Frequency of IR Absorption Spectra of LiF:OH Single Crystal.
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Akhvlediani, Zaira, Dauletbekova, Alma, Baubekova, Guldar, Malikova, Zhadra, Sokhadze, Victor, Akilbekov, Abdirash, and Abdrakhmetova, Ainash
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SINGLE crystals , *ABSORPTION spectra , *NEUTRON irradiation , *IRRADIATION , *RADIOLYSIS , *CRYSTALS , *LITHIUM fluoride - Abstract
For many solids operating under irradiation conditions, the study of their behavior at the neutron irradiation is of importance. Herein, the influence of neutron irradiation conditions on the infrared (IR) absorption spectra of LiF crystals containing different amounts of hydroxyl and metallic impurities is considered. The investigations are carried out for discovering new peculiarities under the extreme irradiation conditions of LiF--being a very important material for practical applications. In the crystals with OH- impurity after the action of neutron irradiation, quite clear bands are appeared in the region of 1900-2200 cm-1. The delivered doses vary from 1014 to 3 x 1017nnvt. LiF crystals are investigated by differing both in qualitative and quantitative contents of OH- ions. With the increase in irradiation dose, the maximum IR absorption of all investigated groups of crystals shifts to the region of low energies. The appearance of a new band in the IR spectrum and its shift as a function of dose is associated with the radiolysis of OH- molecule. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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16. Synthesis of porous indium phosphide with nickel oxide crystallites on the surface
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Suchikova, Yana, Bohdanov, Ihor, Kovachov, Sergii, Lazarenko, Andriy, Bardus, Iryna, Dauletbekova, Alma, Kenzhina, Inesh, and Popov, Anatoli I.
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nickel oxalate ,annealing ,electrochemical etching ,coating ,EDX spectrum - Abstract
In this paper, the technology of synthesis of crystallites and nanocrystallites of nickel oxide on the surface of indium phosphide is described. This technology consists of two stages. In the first stage, porous indium phosphide is formed on the surface of a single crystal of indium phosphide. The formation of such a porous layer provides better adhesion to the surface of the sample. The second stage involves the preparation of the solution that contains nickel ions, application of this solution to the surface of porous indium phosphide, followed by annealing. As a result, NiO/NiC2O4∙2H2O/por- -InP/mono-InP structure was formed. Surface morphological parameters were obtained using scanning electron microscopy and EDX-analysis of chemical composition. Chemical analysis confirmed the partial formation of nickel oxide from nickel oxalate layer by thermal annealing. Using scanning electron microscopy, it has been established that the crystallites have a large scatter in diameter, but they may be divided into three characteristic groups: macro-; meso- and nanocrystallites. Such structures may find prospects for application in electrochemical capacitors and lithium-ion batteries. Further research is needed for methodology improvement to obtain structures with predetermined controlled properties.
- Published
- 2022
17. Paramagnetic Defects and Thermoluminescence in Irradiated Nanostructured Monoclinic Zirconium Dioxide.
- Author
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Ananchenko, Daria V., Nikiforov, Sergey V., Sobyanin, Konstantin V., Konev, Sergey F., Dauletbekova, Alma K., Akhmetova-Abdik, Gulzhanat, Akilbekov, Abdirash T., and Popov, Anatoli I.
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ZIRCONIUM oxide ,THERMOLUMINESCENCE ,ION beams ,ELECTRONS ,IRRADIATION - Abstract
The ESR spectra of nanostructured samples of monoclinic ZrO
2 irradiated by electrons with energies of 130 keV, 10 MeV, and by a beam of Xe ions (220 MeV) have been studied. It has been established that irradiation of samples with electrons (10 MeV) and ions leads to the formation of radiation-induced F+ centers in them. Thermal destruction of these centers is observed in the temperature range of 375–550 K for electron-irradiated and 500–700 K for ion-irradiated samples. It is shown that the decrease in the concentration of F+ centers is associated with the emptying of traps responsible for thermoluminescence (TL) peaks in the specified temperature range. In the samples irradiated with an ion beam, previously unidentified paramagnetic centers with g = 1.963 and 1.986 were found, the formation of which is likely to involve Zr3+ ions and oxygen vacancies. Thermal destruction of these centers occurs in the temperature range from 500 to 873 K. [ABSTRACT FROM AUTHOR]- Published
- 2022
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18. Ab initio calculations of the atomic and electronic structure of MgF2 (011) and (111) surfaces
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Vassilyeva Anna, Eglitis Robert, Kotomin Eugene, and Dauletbekova Alma
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mgf2 ,ab initio calculations ,surfaces ,atomic and electronic structure ,Physics ,QC1-999 - Published
- 2011
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19. High-Energy Heavy Ion Tracks in Nanocrystalline Silicon Nitride.
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Janse van Vuuren, Arno, Mutali, Alisher, Ibrayeva, Anel, Sohatsky, Alexander, Skuratov, Vladimir, Akilbekov, Abdirash, Dauletbekova, Alma, and Zdorovets, Maxim
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PARTICLE tracks (Nuclear physics) ,HEAVY ions ,ELECTRON microscope techniques ,TRANSMISSION electron microscopy ,SILICON nitride ,GRAIN size - Abstract
At present, silicon nitride is the only nitride ceramic in which latent ion tracks resulting from swift heavy ion irradiation have been observed. Data related to the effects of SHIs on the nanocrystalline form of Si
3 N4 are sparse. The size of grains is known to play a role in the formation of latent ion tracks and other defects that result from SHI irradiation. In this investigation, the effects of irradiation with high-energy heavy ions on nanocrystalline silicon nitride is studied, using transmission electron microscopy techniques. The results suggest that threshold electronic stopping power, Set , lies within the range 12.3 ± 0.8 keV/nm to 15.2 ± 1.0 keV/nm, based on measurements of track radii. We compared the results to findings for polycrystalline Si3 N4 irradiated under similar conditions. Our findings suggest that the radiation stability of silicon nitride is independent of grain size. [ABSTRACT FROM AUTHOR]- Published
- 2022
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20. Optical, Structural, and Mechanical Properties of Gd3Ga5O12 Single Crystals Irradiated with 84Kr+ Ions.
- Author
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Karipbayev, Zhakyp T., Kumarbekov, Kuat, Manika, Ilze, Dauletbekova, Alma, Kozlovskiy, Artem L., Sugak, Dmitro, Ubizskii, Sergei B., Akilbekov, Abdirash, Suchikova, Yana, and Popov, Anatoli I.
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SINGLE crystals ,KRYPTON ,FAST ions ,IONS ,CRYSTAL lattices ,LIGHT absorption ,GARNET - Abstract
Herein, the optical absorption, X‐ray diffraction (XRD) analysis data, and mechanical properties along the ion path are analyzed for gadolinium gallium garnet (Gd3Ga5O12 or GGG) single crystals irradiated with fast 84Kr ions to fluences of 1013–1014 ion cm−2. It is found that the optical absorption spectra of Czochralski‐grown unirradiated GGG crystal consist of relatively narrow lines in the UV spectral range associated with the 4f–4f transitions in Gd3+ ions. Transitions from the 6S7/2 ground state to the 6P, 6J, and 6D states in the Gd3+ cation are visible. An additional absorption band is also observed at 350 nm, which is associated with an uncontrolled Ca impurity. In irradiated GGG single crystals, a shift of the fundamental absorption edge by ≈30 nm to the long‐wavelength part of the spectrum is observed. The observed changes are caused by structural disturbances caused by depletion of the surface layer and an increase in the number of displaced atoms accompanied by an increase in the crystal lattice parameter. XRD analysis shows the presence of size effects and deformation of interplanar distances due to the displacement of atoms from the sites of the crystal lattice with subsequent migration. Hardness measurements show ion‐induced softening, which may be due to ion‐induced amorphization. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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21. Ion-Track Template Synthesis and Characterization of ZnSeO 3 Nanocrystals.
- Author
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Dauletbekova, Alma, Akylbekova, Aiman, Sarsekhan, Gulnaz, Usseinov, Abay, Baimukhanov, Zein, Kozlovskiy, Artem, Vlasukova, Liudmila A., Komarov, Fadey F., Popov, Anatoli I., and Akilbekov, Abdirash T.
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BAND gaps ,LATTICE constants ,X-ray diffraction ,COMPUTER software ,PHOTONS - Abstract
ZnSeO
3 nanocrystals with an orthorhombic structure were synthesized by electrochemical and chemical deposition into SiO2 /Si ion-track template formed by 200 MeV Xe ion irradiation with the fluence of 107 ions/cm2 . The lattice parameters determined by the X-ray diffraction and calculated by the CRYSTAL computer program package are very close to each other. It was found that ZnSeO3 has a direct band gap of 3.8 eV at the Γ-point. The photoluminescence excited by photons at 300 nm has a low intensity, arising mainly due to zinc and oxygen vacancies. Photoluminescence excited by photons with a wavelength of 300 nm has a very low intensity, presumably due to electronic transitions of zinc and oxygen vacancies. [ABSTRACT FROM AUTHOR]- Published
- 2022
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22. CdTe Nanocrystal Synthesis in SiO2/Si Ion‐Track Template: The Study of Electronic and Structural Properties.
- Author
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Balakhayeva, Rakhima, Akilbekov, Abdirash, Baimukhanov, Zein, Usseinov, Abay, Giniyatova, Sholpan, Zdorovets, Maxim, Vlasukova, Luydmila, Popov, A. I., and Dauletbekova, Alma
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NANOCRYSTAL synthesis ,BRILLOUIN zones ,PARTICLE tracks (Nuclear physics) ,CURRENT-voltage characteristics ,LATTICE constants - Abstract
The synthesis of CdTe nanocrystals (NCs) is performed by electrochemical deposition into prepared ion tracks in a a‐SiO2/Si‐n template. As a result, CdTe NCs are obtained in a wurtzite (WZ) crystal phase. The measurement of the current–voltage characteristics shows that the CdTe (WZ NC)/SiO2/Si system obtained in this way has n‐type conductivity. Computer simulations using the CRYSTAL computer code show good agreement between experimental and calculated lattice parameters. The theoretical calculations also show that the crystal has a direct bandgap at the Γ point of the Brillouin zone. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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23. Luminescence of LiF crystals doped with uranium
- Author
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Lisitsyna, Ludmila, Denisov, Gennady, Dauletbekova, Alma, Karipbayev, Zhakyp, Valiev, Damir Talgatovich, Marhabaeva, Aiymgul, and Lisitsyn, Viktor Mikhailovich
- Subjects
уран ,люминесценция ,катодолюминесценция ,photoluminescence ,cathodoluminescence ,фотолюминесценция ,кристаллы ,luminescence centers - Published
- 2016
24. MeV-energy Xe ion-induced damage in LiF: The contribution of electronic and nuclear stopping mechanisms.
- Author
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Zabels, Roberts, Manika, Ilze, Schwartz, Kurt, Baizhumanov, Muratbek, Grants, Rolands, Tamanis, Edmunds, Dauletbekova, Alma, and Zdorovets, Maxim
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DISLOCATIONS in metals ,IONS ,IRRADIATION ,NANOINDENTATION ,MICROELECTROMECHANICAL systems - Abstract
The contribution of electronic and nuclear damage mechanisms in the modification of structure and micromechanical properties of LiF crystals irradiated with 52, 224, and 450 MeV Xe ions at fluences 10
10 -1014 ions cm−2 has been studied. The ion-induced formation of dislocations and hardening in LiF at fluences above 1010 ions cm−2 has been observed. The depth profiles of nanoindentation show a joint contribution of electronic excitation and nuclear (impact) mechanisms to the ion-induced hardening. The electronic excitation mechanism dominates in the major part of the ion range while the impact mechanism prevails in a narrow zone at the end of the ion range. The efficiency of hardening produced by electronic excitations is by one order of magnitude higher than that produced by the impact mechanism. Ion-induced prismatic dislocation loops are the main cause of the hardening. At an electronic energy loss above the threshold of 10 keV nm−1 , an ordered dislocation structure is created. HRXRD measurements on heavily irradiated LiF crystals (at fluences above 1012 Xe cm−2 ) reveal a mosaic type substructure composed of nanosize domains tilted under low angles. [ABSTRACT FROM AUTHOR]- Published
- 2016
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25. Preface
- Author
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Dauletbekova, Alma, Skuratov, Vladimir, Kotomin, Eugene A., and Popov, Anatoli I.
- Published
- 2021
- Full Text
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26. SIMULATION OF LATENT TRACK PARAMETERS FOR SiO2 AND Si3N4 IRRADIATED WITH SWIFT IONS.
- Author
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Vlasukova, Ludmila, Komarov, Fadei, Yuvchenko, Vera, Dauletbekova, Alma, and Akilbekov, Abdirash
- Subjects
SILICA ,IONS ,IRRADIATION ,AMORPHOUS substances ,SILICON nitride ,PARAMETER estimation ,ION accelerators - Abstract
The possibility of nanochannel formation in Si-based dielectrics by means of the latent track etching has been estimated in the frame of thermal spike model. We have calculated radii and lifetime of the molten regions or the regions heated to the melting point in amorphous SiO
2 and Si3 N4 irradiated with swift ions. The simulation was carried out using swift ion irradiation regimes available at an ion cyclotron accelerator DC-60 (Astana, Kazakhstan). The radius of molten region along swift ion trajectory was chosen as a criterion for track "etchability" in the case of SiO2 . [ABSTRACT FROM AUTHOR]- Published
- 2014
27. Raman Study of Polycrystalline Si 3 N 4 Irradiated with Swift Heavy Ions.
- Author
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Zhumazhanova, Ainash, Mutali, Alisher, Ibrayeva, Anel, Skuratov, Vladimir, Dauletbekova, Alma, Korneeva, Ekaterina, Akilbekov, Abdirash, and Zdorovets, Maxim
- Subjects
HEAVY ions ,RAMAN spectroscopy technique ,SILICON nitride ,POLYCRYSTALLINE silicon ,RAMAN spectroscopy - Abstract
A depth-resolved Raman spectroscopy technique was used to study the residual stress profiles in polycrystalline silicon nitride that was irradiated with Xe (167 MeV, 1 × 10
11 cm−2 ÷ 4.87 × 1013 cm−2 ) and Bi (710 MeV, 1 × 1011 cm−2 ÷ 1 × 1013 cm−2 ) ions. It was shown that both the compressive and tensile stress fields were formed in the irradiated specimen, separated by a buffer zone that was located at a depth that coincided with the thickness of layer, amorphized due to multiple overlapping track regions. The compressive stresses were registered in a subsurface region, while at a greater depth, the tensile stresses were recorded and their levels reached the maximum value at the end of ion range. The size of the amorphous layer was evaluated from the dose dependence of the full width at half maximum (FWHM) (FWHM of the dominant 204 cm−1 line in the Raman spectra and scanning electron microscopy. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
28. First-principles modeling of the H color centers in MgF2 crystals.
- Author
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Dauletbekova, Alma, Abuova, Fatima, Akilbekov, Abdirash, Kotomin, Eugene, and Piskunov, Sergey
- Abstract
MgF2 with a rutile structure is important wide-gap optical material with numerous applications. We present and discuss the results of calculations for basic hole defects - interstitial F atoms (called also the colour H centers). This study is based on the large scale ab initio DFT calculations using hybrid B3PW exchange-correlation functional as implemented into CRYSTAL computer code. The electronic structure, atomic geometry, charge density distribution are calculated and compared with similar defects in CaF2 fluorite. It is shown that the H centers oriented nearly parallel to the (110) axis are energetically more favourable than those oriented along the (001) axis, in agreement with experiment. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
29. Radiation transformation of the oxygen-containing impurity in LiF crystals doped with different polyvalent cations.
- Author
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Dauletbekova, Alma, Lisitsyna, Liudmila, Korepanov, Vladimir, Lisitsyn, Victor, Trefilova, Larisa, and Kassymkanova, Raigul
- Abstract
Time-resolved spectroscopy and infrared spectroscopy were used to investigate radiation transformation of the oxygen-hydrogen impurity in LiF crystals doped with oxides of different metals Li, W, Ti and Fe with the ab-sorbed dose range of 101-105Gy in the time interval of 10-9-10-1s and in the temperature interval of 15-300 K (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
30. Ab initio calculations of the atomic and electronic structure of MgF (011) and (111) surfaces.
- Author
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Vassilyeva, Anna, Eglitis, Robert, Kotomin, Eugene, and Dauletbekova, Alma
- Abstract
The results of ab initio slab calculations of surface relaxations, rumplings and charge distribution for the different terminations of the MgF (011) and (111) polar surfaces are presented and discussed. We have employed the computer code CRYSTAL with the Gaussian basis set and the hybrid B3PW exchange-correlation functional. Despite the ionic nature of the chemical bonding at both surfaces, a considerable decrease of the optical band gap is predicted (1.3 eV or 10%) for the (111) surface as compared to the bulk. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
31. Electron color center creation in LiF irradiated with Kr ions.
- Author
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Dauletbekova, Alma, Akilbekov, Abdirash, and Zdorovets, Maxim
- Published
- 2010
- Full Text
- View/download PDF
32. Synthesis of ZnO Nanocrystals in SiO2/Si Track Template: Effect of Electrodeposition Parameters on Structure.
- Author
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Dauletbekova, Alma, Vlasukova, Liudmila, Baimukhanov, Zein, Akilbekov, Abdirash, Kozlovskyi, Artem, Giniyatova, Sholpan, Seitbayev, Aibek, Usseinov, Abai, and Akylbekova, Aiman
- Subjects
- *
SPHALERITE , *NANOCRYSTAL synthesis , *SCANNING electron microscopes , *ELECTROPLATING , *AMORPHOUS silicon , *SILICA - Abstract
This paper presents a study of nanoclusters obtained by electrochemical deposition (ECD) of zinc in the a‐SiO2/Si‐n track template. The nanoporous SiO2 layer on Si substrate (track template) has been created by irradiation with swift Xe ions and further etching in HF solution. The morphology of SiO2/Si‐n track templates and precipitated Zn‐based clusters are examined using a scanning electron microscope JSM 7500F. The crystallographic structure of the Zn‐based precipitates was investigated by means of X‐ray diffraction (XRD). X‐ray analysis is carried out on a D8 ADVANCE ECO X‐ray diffractometer. The Bruker AXSDIFFRAC.EVAv.4.2 software and the international ICDD PDF‐2 database are used to identify the phases and study the crystal structure. From XRD data, it has been found the formation of three crystalline phases of zinc oxide nanocrystals electro‐deposited into SiO2/Si track template: wurtzite, sphalerite, and rock salt structures. Wurtzite is obtained on an amorphous surface of silicon dioxide. Possible mechanisms of ZnO formation instead of metal Zn nanocrystals are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
33. The Synthesis of porous indium phosphide with nickel oxide crystallites on the surface
- Author
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Suchikova, Yana, Bohdanov, Ihor, Kovachov, Sergii, Lazarenko, Andriy, Bardus, Iryna, Dauletbekova, Alma, Kenzhina, Inesh, and Popov, Anatoli I.
- Full Text
- View/download PDF
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