Bulgarian Academy of Sciences
Institute of Optical Materials and Technologies
"Acad. Jordan Malinowski"
Bulgarian Academy of Sciences
Institute of Optical Materials and Technologies
"Acad. Jordan Malinowski"
"Acad. Jordan Malinowski"
Acad. J. Malinowski (1923 - 1996)
Academician Jordan Malinowski was born on 03.06.1923 ...
National projects
National Science Infrastructure
INFRAMAT
National Science Infrastructure
INFRAMAT
INFRAMAT
Most significant scientific achievement for 2022
Most significant scientific achievement for 2022: Electronic structure and plasmonic activity in co-evaporated Ag-In bimetallic alloys, coordinator Assoc. Prof. Rosen Todorov
Thin Ag-In films, covering the whole range of compositions from 0 to 100 at. % In, were deposited by thermal co-evaporation. The conditions for preparation of samples with preliminary given composition and thickness were determined...
Most significant scientific achievement for 2022
Most significant scientific achievement for 2022: Electronic structure and plasmonic activity in co-evaporated Ag-In bimetallic alloys, coordinator Assoc. Prof. Rosen Todorov
Optical constants, Lorentzian component of the dielectric function of Ag-In films.
Band structure of intermetallic compounds and emission spectra of Ag-In nanoparticlesThin Ag-In films, covering the whole range of compositions from 0 to 100 at. % In, were deposited by thermal co-evaporation. The conditions for preparation of samples with preliminary given composition and thickness were determined. It has been established by X-ray diffraction that a chemical interaction between the two elements – silver and indium – leading to formation of solid solutions and intermetallic compounds, is realized without further processing of the coatings, and their phase composition corresponds well to that described in the T-x diagram of the Ag-In system. For the first time, through spectroscopic ellipsometry, the spectra of the complex dielectric permittivity, ε were determined for thin films from the investigated system. The compositional dependence of ε was analyzed according to the electronic structure, calculated using the Density Functional Theory (DFT).
It has been determined that the thin films, which contain the intermetallic crystalline compounds – Ag3In, Ag9In4 и AgIn2 in their structure, possess 2 times higher efficiency for excitement of a localized surface plasmon resonance (LSPR) in the ultraviolet (UV) spectral interval in comparison to the pure indium. The calculated Lorentz part of the complex dielectric permittivity reveals that the increase of the indium content in the thin Ag-In films leads to a decrease of the interband transitions energy up to 2 eV and, respectively, to a decrease of the number of electrons participating in interband transitions with energies from 4 to 6 eV. Due to this, a decrease of the optical losses in the UV spectral range is observed, while the real part of the dielectric function stays negative because of the metallic character of these compounds. As a result, an increase of the quality factor for excitation of LSPR – QLSPR = -ε′/ε′′ is acquired. The obtained new materials are useful for application in methods with ultra-high sensitivity, such as surface-enhanced UV fluorescence and attosecond spectroscopies.
The scientific research was financed by the National Science Fund, contract КП-06-38/8 – 2019, and its main results were published in: R. Todorov, T. Hristova-Vasileva, V. Katrova, A. Atanasova, G. Milushev, Electronic structure and plasmonic activity in co-evaporated Ag-In bimetallic alloys, Journal of Alloys and Compounds 897 (2022) 163253 (WoS IF = 6.371, Q1), https://doi.org/10.1016/j.jallcom.2021.163253.
Most significant scientific achievement for 2022
Most significant scientific achievement for 2022: Electronic structure and plasmonic activity in co-evaporated Ag-In bimetallic alloys, coordinator Assoc. Prof. Rosen Todorov
Optical constants, Lorentzian component of the dielectric function of Ag-In films.
Band structure of intermetallic compounds and emission spectra of Ag-In nanoparticles
Thin Ag-In films, covering the whole range of compositions from 0 to 100 at. % In, were deposited by thermal co-evaporation. The conditions for preparation of samples with preliminary given composition and thickness were determined. It has been established by X-ray diffraction that a chemical interaction between the two elements – silver and indium – leading to formation of solid solutions and intermetallic compounds, is realized without further processing of the coatings, and their phase composition corresponds well to that described in the T-x diagram of the Ag-In system. For the first time, through spectroscopic ellipsometry, the spectra of the complex dielectric permittivity, ε were determined for thin films from the investigated system. The compositional dependence of ε was analyzed according to the electronic structure, calculated using the Density Functional Theory (DFT).Band structure of intermetallic compounds and emission spectra of Ag-In nanoparticles
It has been determined that the thin films, which contain the intermetallic crystalline compounds – Ag3In, Ag9In4 и AgIn2 in their structure, possess 2 times higher efficiency for excitement of a localized surface plasmon resonance (LSPR) in the ultraviolet (UV) spectral interval in comparison to the pure indium. The calculated Lorentz part of the complex dielectric permittivity reveals that the increase of the indium content in the thin Ag-In films leads to a decrease of the interband transitions energy up to 2 eV and, respectively, to a decrease of the number of electrons participating in interband transitions with energies from 4 to 6 eV. Due to this, a decrease of the optical losses in the UV spectral range is observed, while the real part of the dielectric function stays negative because of the metallic character of these compounds. As a result, an increase of the quality factor for excitation of LSPR – QLSPR = -ε′/ε′′ is acquired. The obtained new materials are useful for application in methods with ultra-high sensitivity, such as surface-enhanced UV fluorescence and attosecond spectroscopies.
The scientific research was financed by the National Science Fund, contract КП-06-38/8 – 2019, and its main results were published in: R. Todorov, T. Hristova-Vasileva, V. Katrova, A. Atanasova, G. Milushev, Electronic structure and plasmonic activity in co-evaporated Ag-In bimetallic alloys, Journal of Alloys and Compounds 897 (2022) 163253 (WoS IF = 6.371, Q1), https://doi.org/10.1016/j.jallcom.2021.163253.
Most significant applied scientific achievement for 2022
Structural, Morphological and Optical Properties of Nanostructured ZrO2 Films Obtained by an Electrochemical Process at Different Deposition Temperatures, coordinator Assoc. Prof. Konstantin Lovchinov
The impact of the deposition temperature (in the range from 60 to 80 °C) in ZrO2 films obtained by...
Most significant applied scientific achievement for 2022
Structural, Morphological and Optical Properties of Nanostructured ZrO2 Films Obtained by an Electrochemical Process at Different Deposition Temperatures, coordinator Assoc. Prof. Konstantin Lovchinov
Electrochemical deposition of ZrO2 layers; characterization of structure, surface roughness and morphology of the deposited layers.The impact of the deposition temperature (in the range from 60 to 80 °C) in ZrO2 films obtained by the electrochemical deposition process on SnO2-covered glass substrates is studied. The solution in which the deposition takes place is aqueous, containing ZrOCl2 with a concentration of 3 × 10−5 M and KCl with a concentration of 0.1 M. By implementing X-ray diffraction (XRD), optical profilometry, scanning electron microscopy (SEM), and UV-VIS-NIR spectroscopy, the temperature dependence of ZrO2 films properties was revealed. The X-ray Diffraction XRD spectra showed six different diffraction maxima ((−111)M, (101)T, (111)M, (112)M, (202)M, and (103)M) associated with the electrochemical ZrO2 layers, and the polycrystalline structure of the films was confirmed at all deposition temperatures. The determination of the average roughness did not indicate significant temperature dependence in the deposited layers. SEM micrographs showed that the layers were composed of grains, most of them of a regular shape, although their size increased slightly with an increased deposition temperature. The coarsest-grained structure was observed for the layers deposited at 80 °C. It was demonstrated that the deposition temperature weakly impacts the reflectance and transmittance spectra of the ZrO2 layers. Such layers with low values of specular and high values of diffuse transition, and reflection in the spectral range from 380 to 800 nm, can be applied to various optoelectronic devices such as thin-film solar cells.
The research was carried out in cooperation with the Central Laboratory of Solar Energy and New Energy Sources - BAS and with the Faculty of Physics of SU "St. Kliment Ohridski". It is financially supported by FNI (grant KΠ–06–H38/7/2019). The results were published in the special issue "Electrochemical Deposition: Properties and Applications", edited by Assoc. Prof. Konstantin Lovchynov and Assoc. Prof. Gergana Alexieva, of the journal "Coatings" (IF=3.236, Q2): Lovchinov, K., Gergova, R., Alexieva, G., “Structural, Morphological and Optical Properties of Nanostructured ZrO2 Films Obtained by an Electrochemical Process at Different Deposition Temperatures”, Coatings, 12 (2022) 972, DOI: 10.3390/coatings12070972.
Most significant applied scientific achievement for 2022
Structural, Morphological and Optical Properties of Nanostructured ZrO2 Films Obtained by an Electrochemical Process at Different Deposition Temperatures, coordinator Assoc. Prof. Konstantin Lovchinov
Electrochemical deposition of ZrO2 layers; characterization of structure, surface roughness and morphology of the deposited layers.
The impact of the deposition temperature (in the range from 60 to 80 °C) in ZrO2 films obtained by the electrochemical deposition process on SnO2-covered glass substrates is studied. The solution in which the deposition takes place is aqueous, containing ZrOCl2 with a concentration of 3 × 10−5 M and KCl with a concentration of 0.1 M. By implementing X-ray diffraction (XRD), optical profilometry, scanning electron microscopy (SEM), and UV-VIS-NIR spectroscopy, the temperature dependence of ZrO2 films properties was revealed. The X-ray Diffraction XRD spectra showed six different diffraction maxima ((−111)M, (101)T, (111)M, (112)M, (202)M, and (103)M) associated with the electrochemical ZrO2 layers, and the polycrystalline structure of the films was confirmed at all deposition temperatures. The determination of the average roughness did not indicate significant temperature dependence in the deposited layers. SEM micrographs showed that the layers were composed of grains, most of them of a regular shape, although their size increased slightly with an increased deposition temperature. The coarsest-grained structure was observed for the layers deposited at 80 °C. It was demonstrated that the deposition temperature weakly impacts the reflectance and transmittance spectra of the ZrO2 layers. Such layers with low values of specular and high values of diffuse transition, and reflection in the spectral range from 380 to 800 nm, can be applied to various optoelectronic devices such as thin-film solar cells.The research was carried out in cooperation with the Central Laboratory of Solar Energy and New Energy Sources - BAS and with the Faculty of Physics of SU "St. Kliment Ohridski". It is financially supported by FNI (grant KΠ–06–H38/7/2019). The results were published in the special issue "Electrochemical Deposition: Properties and Applications", edited by Assoc. Prof. Konstantin Lovchynov and Assoc. Prof. Gergana Alexieva, of the journal "Coatings" (IF=3.236, Q2): Lovchinov, K., Gergova, R., Alexieva, G., “Structural, Morphological and Optical Properties of Nanostructured ZrO2 Films Obtained by an Electrochemical Process at Different Deposition Temperatures”, Coatings, 12 (2022) 972, DOI: 10.3390/coatings12070972.