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Your search keyword '"Miodrag Oljaca"' showing total 3 results
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3 results on '"Miodrag Oljaca"'

1. Metal doping of dielectric thin layers by electric field assisted film dissolution

Author

Vesna Janicki, Jordi Sancho-Parramon, Miodrag Oljaca, and Boris Okorn

Subjects
010302 applied physics, Materials science, Thin layers, Dopant, Borosilicate glass, 02 engineering and technology, Dielectric, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, Condensed Matter::Materials Science, Chemical engineering, Ellipsometry, Glass Poling, Atomic and Molecular Physics, 0103 physical sciences, Materials Chemistry, Ceramics and Composites, Thin film, Metal doping, Glass poling, Electric field assisted dissolution, Refractive index, 0210 nano-technology, Dissolution
Abstract

The incorporation of metal ions in dielectric layers by means of electric field assisted film dissolution is investigated. The samples consist of alkali-containing glass substrates coated first with SiO 2 and then Ag thin films. The application of moderately elevated temperatures and DC voltages induces thermal poling in the glass matrix and metal film dissolution, resulting in the incorporation of metal ions in both dielectric layer and glass matrix. First, the process dynamics are simulated by modelling the migration of metal film ions and alkali species under an applied electric field. Numerical solution of the model indicates that metal ions progressively dope the dielectric layer until they reach the glass matrix. Then the dopant distribution in the layer becomes steady-state and further injection of ions contributes to increase the dopant concentration in glass. The influence on the process of alkali and dopant ion mobilities and alkali ion concentration is analysed. Additionally, Ag doping of SiO 2 layers deposited on soda-lime and borosilicate glasses is experimentally carried out and characterized using spectroscopic ellipsometry. The evolution of refractive index profiles through both, SiO 2 layer and glass substrate, is correlated with ion migration and confirms the model trends. Overall, this study shows that glass poling and film dissolution can be used to control metal doping of dielectric layers, with potential application in optical and photonic devices.

Published
2021

2. Influence of thermal treated carbon black conductive additive on the performance of high voltage spinel Cr-doped LiNi0.5Mn1.5O4 composite cathode electrode

Author

Tobias Placke, Miodrag Oljaca, Archit Lal, Xin Qi, Martin Winter, Dupasquier Aurelien L, Berislav Blizanac, Philip Niehoff, and Jie Li

Subjects
Materials science, Renewable Energy, Sustainability and the Environment, Spinel, Cr doped, High voltage, Carbon black, engineering.material, Condensed Matter Physics, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Thermal, Electrode, Materials Chemistry, Electrochemistry, engineering, Composite cathode, Composite material, Electrical conductor
Published
2015

3. The effects of induced dissipative small-scale motions and mixing on optical distortion in a plane shear layer.

Author

MIODRAG OLJACA and ARI GLEZER

Subjects
SHEAR waves, FLUORESCENCE, LASERS, REFRACTION (Optics), TURBULENT boundary layer, IMAGING systems, OPTICS
Abstract

Optical distortion through a plane shear layer between two uniform streams of unequal temperatures is investigated using imaging of scalar mixing by planar laser-induced fluorescence (LIF). Simultaneous fluorescence intensity measurements of disodium fluorescein and rhodamine B (the fluorescence of the latter is temperature dependent) are used to extract the temperature distribution within the plane of a laser sheet. This planar imaging technique allows a direct measurement of the index of refraction field, which is used to determine optical distortions in the imaging plane. While a given ray within the sheet is refracted at a cumulative angle that depends on the local index of refraction gradient along its path, LIF measurements in the cross-stream plane of the flow show substantial optical distortions near the upstream and downstream edges of the primary vortices where the angle between the local temperature (or index) gradient and the wavevector of the incident light is large. These distortions are manifested by the appearance of low- and high-intensity streaks that are advected with the flow and whose characteristic spatial scales significantly diminish with the onset of small-scale (mixing) transition. The formation of secondary (streamwise) vortical structures leads to substantial spanwise variations in index of refraction and consequently to optical distortions that vary with the phase of the base flow and can exceed the distortions in the cross-stream plane. An important aim of the present research is the investigation of the effects of direct actuation of small-scale motions on the mixing and consequently on optical distortion within the shear layer. The actuation suppresses the formation of the large coherent vortical structures and leads to localized enhancement of dissipation and reduction in turbulent kinetic energy. The actuation enhances mixing across the entire width of the forced shear layer and leads to significant reduction of optical distortion, suggesting that active small-scale mixing can play a significant role in the mitigation of aero-optical effects through turbulent shear flows. [ABSTRACT FROM AUTHOR]

Published
2009
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