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1
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Growing Large Size Complex Oxide Single Crystals by Czochralski Technique for Electronic Devices

100%
Solskii I., Sugak D., Vakiv M.
Acta Physica Polonica A
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2013
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vol. 124
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issue 2
314-320
EN
This paper is devoted to the use and further development of the single crystal growing technique invented by Professor Jan Czochralski (1885-1953). The possibilities of the Czochralski technique are demonstrated. Further improvements were introduced at the Scientific Research Company "Carat" (Lviv, Ukraine) to grow large size complex oxide single crystals. The paper presents an overview of some single crystals grown with the use of a modified technology. Growth parameters and properties of resulting crystals are summarized to show a high potential of the Czochralski technique as an industrial technology to grow large-size, high quality, and structurally perfect single crystals of complex oxides.
2
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Induced Absorption in Gadolinium Gallium Garnet Irradiated by High Energy ^{235}U Ions

100%
Potera P., Ubizskii S., Sugak D., Schwartz K.
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EN
The present work is devoted to investigation of optical absorption in pure Gd_{3}Ga_{5}O_{12} (GGG) single crystals in the spectral range 0.2-1.1 μm induced under influence of the ^{235}U ions irradiation with energy 2640 MeV and a fluence 10^{9}-10^{11} cm^{-2}. The induced absorption for 10^{9} cm^{-2} is caused by recharging of point defects, both growth ones and impurities. After irradiation by ^{235}U ions with fluences starting from 3 × 10^{9} cm^{-2} the absorption rise is probably caused by contribution of the lattice destroying as a result of heavy ion bombardment as well as radiation displacement defects.
3
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NMR Analysis of Mg Ion Localization in LiNbO_{3} Crystal

100%
Yatsenko A., Yevdokimov S., Sugak D., Solskii I.
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EN
The analysis of cation sublattices population in magnesium doped LiNbO_{3} crystals is carried out. It is shown that volume concentration of lithium vacancies (V_{Li}) monotonously increases with increasing of MgO content in the crystal up to the threshold value. A series of LiNbO_{3} crystals with various concentration of Mg^{2+} were investigated by ^{7}Li and ^{93}Nb Nuclear Magnetic Resonance (NMR). It is concluded that the peculiarities of NMR spectra in Mg-doped LiNbO_{3} crystals can be explained by the formation of defect complexes including Mg_{Li} ions and V_{Li} on the shortest distances between them.
4
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Optical Properties of GGG Epitaxial Films Grown from PbO-B₂O₃-V₂O₅ Flux

88%
Syvorotka I., Sugak D., Luchechko A., Zhydachevskyy Y., Ubizskii S.
Acta Physica Polonica A
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2018
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vol. 133
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issue 4
954-958
EN
The paper reports a growth of the high-quality Gd₃Ga₅O₁₂ (GGG) homoepitaxial films by the liquid phase epitaxy technique using the PbO-B₂O₃ and PbO-B₂O₃-V₂O₅ fluxes. The influence of the flux composition containing V₂O₅ as well as the growth temperature is discussed basing on the optical absorption and the electron probe micro analysis results.
5
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The Passively Q-switched Microchip Nd:YAG Laser Optimization for Rangefinder Applications

76%
Buryy O., Iznin A., Syvorotka I., Sugak D., Ubizskii S., Vakiv M.
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issue 1
238-243
EN
The problem of Q-switched microchip Nd^{3+}:YAG/Cr^{4+}:YAG laser optimization is considered. In accordance with requirements of laser location, the optimization consists in determination of such values of the saturable absorber (Cr^{4+}:YAG) thickness, the output laser mirror reflectivity and the pumping power, that ensure the generation of the sufficiently short ( ≈0.5 ns) laser pulses at the repetition rate of about 10 kHz and the peak power of about 1 kW or higher. Firstly, the dependences of the laser radiation parameters on the constructive ones are analyzed in the frames of Xiao-Bass model of Q-switched microchip laser. The obtained dependences are used for laser optimization. As it is shown, the parameters of laser radiation close to predominating ones are achieved at the absorber thickness of 140 μm, the output mirror reflectivity of 0.97 and the pumping power of 2.5 W.
6
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Eight-Channel Optical Add Drop Multiplexer Based on Ring Resonator Using LNOI Channel Waveguides

76%
Kumar H., Janyani V., Buryy O., Ubizskii S., Sugak D., Singh G.
Acta Physica Polonica A
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2018
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vol. 133
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issue 4
997-999
EN
In this paper we report on an eight-channel optical add drop multiplexer based on ring resonator using lithium niobate on insulator channel waveguides. It is suitable for a DWDM-GPON network with channel spacing of 100 GHz in C-band and data rate is 10 Gbps. The insertion loss at the drop port is maximum 1.2 dB and the Q-factor is 1636. It can be used as multiplexer as well as demultiplexer in 8-channel DWDM systems.
7
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Possibility of Gamma-Induced Sensibilization Process in Rare-Earth Doped Yag Crystals

76%
Kaczmarek S., Matkovskii A., Mierczyk Z., Kopczyński K., Sugak D., Durygin A., Frukacz Z.
Acta Physica Polonica A
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1996
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vol. 90
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issue 2
285-293
EN
The influence of gamma irradiation on optical and lasing properties of Nd:YAG, Er:YAG and CTH:YAG single crystals was studied. The increase in optical output was established for rods without thermal annealing. The possible mechanisms of radiation sensibilization are discussed.
8
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Optical Detection of Paramagnetic Centres in Activated Oxyfluoride Glass-Ceramics

76%
Rogulis U., Fedotovs A., Antuzevics A., Berzins D., Zhydachevskyy Y., Sugak D.
Acta Physica Polonica A
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2018
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vol. 133
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issue 4
785-788
EN
Electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD) and EPR detected via MCD (MCD-EPR) investigations have been performed on rare-earth activated oxyfluoride glasses and glass-ceramics. Er³⁺, Gd³⁺, and Mn²⁺ activators in oxyfluoride glass-ceramics show paramagnetic MCD behaviour and the MCD-EPR has been detected. The results of the MCD-EPR measurements for the Er-doped oxyfluoride glass-ceramics showed that Er³⁺ ions in the CaF₂ crystallites in these ceramics embed only in the cubic symmetry environment, similarly to the previous observations of cubic Gd³⁺ centres in the glass-ceramics containing CaF₂. Finally, the correlation of optics and paramagnetic centres is discussed for Mn-doped YAlO₃ ceramics.
9
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Optical Absorption and Luminescence of Gd_{3}Ga_{5}O_{12}:Cr,Mg Epitaxial Films

76%
Zakharko Y., Syvorotka I., Luchechko A., Syvorotka I., Sugak D., Vakiv M.
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issue 1
111-113
EN
The optical absorption, emission spectra and luminescence decay kinetics under photoexcitation of Gd_{3}Ga_{5}O_{12} (GGG) garnet epitaxial films doped with Cr^{3+} ions and co-doped with Cr^{3+} and Mg^{2+} ions have been investigated. Luminescence of the GGG:Cr films due to ^{4}T_{2} → ^{4}A_{2} and ^{2}E → ^{4}A_{2} transitions in Cr^{3+} ions have been observed. Increase of the activator ions concentration has an influence on the intensity and decay time of Cr^{3+} ions photoluminescence. Introduction of the magnesium ions leads to partial transformation of chromium valence state (Cr^{3+} → Cr^{4+}) and to the appearance of a broad absorption band with the maximum at 860 nm. The narrow lines with luminescence maxima at 704 and 706 nm have arisen in the highly doped GGG:Cr,Mg films.
10
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Thermal Behaviour of PrCo_{1-x}Fe_xO₃ Probed by X-ray Synchrotron Powder Diffraction and Impedance Spectroscopy Measurements

76%
Pekinchak O., Sugak D., Ubizskii S., Suhak Y., Fritze H., Vasylechko L.
Acta Physica Polonica A
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2018
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vol. 133
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issue 4
798-801
EN
Crystal structure and transport properties of the mixed praseodymium cobaltites-ferrites PrCo_{1-x}Fe_xO₃ have been studied in the temperature range of 298-1173 K by a combination of in situ X-ray synchrotron powder diffraction and temperature dependent impedance spectroscopy measurements. In situ high temperature powder diffraction examination of PrCo_{1-x}Fe_xO₃ series revealed considerable anomalies in the lattice expansion which are especially pronounced for the cobalt-rich specimens. These anomalies, which are reflected in a sigmoidal dependence of the unit cell dimensions and in the considerable increase of the thermal expansion coefficients, are obviously associated with transitions of Co^{3+} ions from low spin to the higher spin states and the coupled metal-insulator transitions, occurring in in rare earth cobaltites at the elevated temperatures. Indeed, the temperature-dependent impedance measurements clearly prove the change of conductivity type from dielectric to the metallic behaviour in the mixed cobaltite-ferrites PrCo_{1-x}Fe_xO₃ at the elevated temperatures.
11
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In situ Investigation of OH^{-} Absorption in LiNbO_{3} and LiNbO_{3}:MgO Crystals during Reducing/Oxidizing Annealing

76%
Sugak Y., Sugak D., Zhydachevskii Y., Solskii I., Buryy O., Ubizskii S., Becker K.
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EN
The work presents experimental results of an in situ investigation of the OH^{-} absorption in pure and MgO-doped LiNbO_{3} crystals during reducing (95% Ar + 5% H_{2}) and oxidizing (O_{2}) high-temperature treatments in the temperature range from room temperature to 820 K. The absorption spectra measured in situ at high temperatures in reducing/oxidizing atmospheres have been analyzed. The origin of the changes in optical absorption caused by heating of the crystal is discussed in terms of the OH-bonds orientation change.
12
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Design and Characterization of Resonator Mirrors for Microlasers on the Base of YAlO_3 Single Crystals Activated with Nd^{3+} and Tm^{3+} Ions

64%
Ilyina O., Hajduchok V., Izhnin O., Sugak D., Kuzmak R., Syvorotka I., Dyachok Y., Groshovyy I., Vakiv M.
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issue 1
244-247
EN
Most of the challenges in laser technology can be overcome by using yttrium-aluminum perovskite (YAlO_3, YAP). These crystals are characterized by more advantages than typical Y_3Al_{5}O_{12} (YAG) crystals. However, the creation of microlasers with these materials is just under development. The aim of the work was to theoretically design the input and output cavity mirrors for microlasers on the base of YAlO_3:Nd or YAlO_3:Tm single crystals, and to investigate those resonators obtained according to the theoretical design using electron beam evaporation method.
13
Content available remote

UV and Gamma Irradiation Effect in Spectroscopic and Lasing Properties of Er^{3+} doped Yttrium-Aluminium Garnet, Yttrium Orthoaluminate and Lithium Niobate Crystals

64%
Kaczmarek S., Pracka I., Mierczyk Z., Kopczyński K., Piramidowicz R., Malinowski M., Kisielewski J., Matkovskii A., Sugak D.
Acta Physica Polonica A
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1996
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vol. 90
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issue 2
411-418
EN
Optical features (absorption and luminescence spectra) for Er^{3+} doped yttrium-aluminium garnet (YAG), yttrium orthoaluminate (YAP) and LiNbO3 crystals as well as their changes after UV and gamma irradiations are presented. Possibility of gamma-induced sensibilization process in Er^{3+} doped crystals is discussed. Positive result for non-pre-annealed gamma-irradiated rods of Er^{3+}:YAG crystal was stated.
14
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Influence of the γ-Radiation on the Generation Characteristics of the YAlO_{3}:Nd Crystals

64%
Sugak D., Matkovskii A., Grabovskii V., Prokhorenko V., Suchocki A., Durygin A., Solskii I., Shakhov A.
Acta Physica Polonica A
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1998
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vol. 93
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issue 4
643-648
EN
The results of investigation of the influence of γ-radiation by ^{60}Co-source on the YAlO_{3}:Nd laser generation characteristics are presented in this paper. The significant decrease in the output energy after γ-irradiation was obtained. The energetic characteristics are restored after illumination of the γ-irradiated laser rods by 1000-10000 pulses of the pumping lamp light. The additional absorption spectrum is induced by γ-irradiation in the crystals. The nature of the created in this way colour centres is discussed. The mechanism of influence of the colour centres on generation properties of the crystals is discussed.
15
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Investigation of Co Ions Diffusion in Gd₃Ga₅O₁₂ Single Crystals

52%
Sugak D., Syvorotka I., Yakhnevych U., Buryy O., Vakiv M., Ubizskii S., Włodarczyk D., Zhydachevskyy Y., Pieniążek A., Jakiela R., Suchocki A.
Acta Physica Polonica A
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2018
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vol. 133
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issue 4
959-964
EN
Spatial changes of properties of Gd₃Ga₅O₁₂ (GGG) single crystals caused by diffusion of cobalt ions during high-temperature annealing (1200°C, 24 h) in Co₃O₄ powder are investigated. The registration of these changes was carried out by optical spectrophotometry, microscopy and micro-Raman scattering methods. Changes in structure of near-surface layers of the crystal were investigated by X-ray diffraction technique. It was shown that the additional absorption induced by annealing is related to intra-center optical transitions in Co²⁺ ions, which occupy tetrahedral positions in the garnet structure at the distances of 250-500 μm from the crystal surface. The dependence of induced absorption with depth has got a non-monotonous character with a maximum at 400 μm. A comparison of the results obtained by different methods allows to suppose that the thermal treatment of GGG in the presence of cobalt ions leads to formation of the structurally and chemically non-uniform layer with a width about 500 μm.
16
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Optical Investigation of the Cu Ions Diffusion into Bulk Lithium Niobate

52%
Sugak D., Syvorotka I., Yakhnevych U., Buryy O., Martynyuk N., Ubizskii S., Zhydachevskyy Y., Suchocki A., Kumar H., Janyani V., Singh G.
Acta Physica Polonica A
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2018
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vol. 133
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issue 4
965-972
EN
Spatial changes of optical properties of bulk LiNbO₃ crystal were investigated after annealing in CuO powder. The incorporation of copper ions into the crystal was confirmed by registration of additional absorption spectra that revealed formation of the absorption bands of both Cu⁺ (400 nm) and Cu²⁺ (1000 nm) ions. The changes of optical absorption caused by thermal treatment were registered along the direction of diffusion by the probe beam perpendicular to this direction. The anisotropy of diffusion was revealed. The maxima were observed on the depth dependences of additional absorption both for the wavelengths of 400 and 1000 nm for all main crystallographic directions. The concentrations of copper ions were calculated in accordance with the Smakula-Dexter formula. The X-ray diffraction study revealed reflexes which probably belong to CuNb₂O₆, CuNbO₃ and CuO. The halo was observed on these diffraction patterns that confirms the formation of the scattering centers (about 1 nm in diameter) in the near-surface region.
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