Browsing by Author "Burak, Ya. V."
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Item AFM study of Ni- and Cu-doped Li2B4O7 lass surface(Видавництво Львівської політехніки, 2012) Adamiv, V. T.; Bolesta, I. M.; Burak, Ya. V.; Kushnir, O. O.; Karbovnyk, I. D.The results of atomic force microscopy (AFM) studies of surface of the lithium tetraborate glasses doped with Cu, Ni and annealed in the hydrogen (H2) atmosphere are presented.Item Cathodoluminescence of the un-doped and doped noncrystalline lithium – potassium – borate compounds(Видавництво національного університету „Львівська політехніка”, 2009) Adamiv, V. T.; Padlyak, B. V.; Savczyn, V. P.; Teslyuk, I. M.; Burak, Ya. V.Item Current-voltage characteristics of MDM and MDSCM structures on basis of lithium borates(Видавництво Львівської політехніки, 2012) Adamiv, V. T.; Burak, Ya. V.; Say, I. S.; Teslyuk, I. M.; Turko, B. S.; Panasyuk, M. R.The results of investigations of current-voltage characteristics for metal dielectric-metal and metaldielectric-semiconductor-metal structures, where crystalline and glass lithium borates used as dielectrics, are presented.Item Epr spectroscopy of the Mn2+ and Cu2+ centres in lithium and potassium-lithium tetraborate glasses(Видавництво національного університету “Львівська політехніка”, 2009) Padlyak, B. V.; Wojtowicz, W.; Adamiv, V. T.; Burak, Ya. V.; Teslyuk, I. M.Item Optical spectroscopy of Nd-doped borate glasses(Видавництво Львівської політехніки, 2012) Padlyak, B. V.; Ryba-Romanowski, W.; Lisiecki, R.; Adamiv, V. T.; Burak, Ya. V.; Teslyuk, I. M.Optical absorption, luminescence excitation and emission spectra as well as luminescence kinetics of the Nd3+ centres in glasses with Li2B4O7:Nd, LiCaBO3:Nd, and CaB4O7:Nd compositions containing 0.5 and 1.0 mol. % Nd2O3 have been investigated and analyzed. Using Judd-Ofelt theory oscillator strengths (f) and phenomenological intensity parameters W t ( W 2, W 4, and W 6) for all investigated glasses were determined. Radiative transitions rates (Wr), radiative lifetimes (τrad), and branching ratios (β) for Nd3+ centres have been calculated. Measured lifetimes for Nd3+ centres in the 4F3/2 emitting level are compared with those calculated and quantum efficiency (h) have been estimated.Item Optical, elastical and piezooptical properties of the β-BaB2O4 and Li2B4O7 borate crystals(Видавництво Національного університету «Львівська політехніка», 2002) Adamiv, V. T.; Burak, Ya. V.; Martynyuk-Lototska, I. Yu.; Kostyrko, M. E.; Vlokh, R. O.; Romanyuk, G. M.; Shranz, W.; Institute of the Physical Optics, Ukraine; Lviv Polytechnic National University; Institut fur Experimental Physic, AustriaThe optical, elastic and piezooptical properties of the borate crystals have been investigated. The dispersions of the indexes refraction of the Li2B4O7 crystals have been determinated in wavelength range 350 - 650 nm. The results of the measurement velocity of the longitudinal and transverse ultrasonic waves on borate crystals are presented. Using ultrasonic velocity measurements the components of the elastic matrix Cmn of these crystals have been determined. Using the determined values of the elastooptical tensor components the acoustooptical quality M2 of β-BaB2O4 crystals has been calculatedItem Pulse X-Ray conductivity of MDM and MDSCM structures on basis of lithium borates(Видавництво Львівської політехніки, 2012) Adamiv, V. T.; Burak, Ya. V.; Say, I. S.; Teslyuk, I. M.; Turko, B.; Panasyuk, M. R.The results of investigations of pulse X-ray conductivity for metal-dielectric-metal and metal-dielectricsemiconductor-metal structures, where thin plates of Li2B4O7 or Li6GdB3O9 single crystals, and Li2B4O7 glasses used as dielectrics, have been presented.Item Synthesis and optical spectroscopy of borate glasses, doped with terbium and dysprosium(Видавництво Львівської політехніки, 2012) Padlyak, B. V.; Pieprzyk, B.; Drzewiecki, A.; Adamiv, V. T.; Burak, Ya. V.; Teslyuk, I. M.The high optical quality glasses with CaB4O7:Tb, LiCaBO3:Tb, CaB4O7:Dy, and LiCaBO3:Dy compositions containing 0.5 and 1.0 mol. % Tb2O3 and Dy2O3 have been obtained. By electron paramagnetic resonance (EPR) and optical spectroscopy it was shown that the Tb and Dy impurities are incorporated in the CaB4O7 and LiCaBO3 glass network as Tb3+ (4f8, 7F6) and Dy3+ (4f9, 6H15/2) ions, exclusively. All observed f – f transitions of Tb3+ and Dy3+centres in optical absorption, luminescence excitation and emission spectra have been identified. Luminescence kinetic shows single exponential decay for Tb3+ and Dy3+ centres in the CaB4O7 and LiCaBO3 glasses. Lifetimes for main emitting levels of Tb3+ and Dy3+ centres in all investigated glasses were determined at T = 300 K. Spectroscopy shows that obtained glasses are promising luminescent materials.