Перегляд за автором "Yunakov, N. N."

Зараз показано 1 - 9 з 9
  • Зображення мініатюри
    Публікація
    Absorption Spectra of Thin Films Compounds in the PbCl-CuCl System
    (Eskisehir Technical University, 2021) Kovalenko, E. N.; Yunakova, O. N.; Yunakov, N. N.
  • Зображення мініатюри
    Публікація
    Absorption Spectrum of KPb2Br5 Thin Films.
    (Eskisehir Technical University, 2021) Kovalenko, E. N.; Yunakova, O. N.; Yunakov, N. N.
  • Зображення мініатюри
    Публікація
    Effect of iodine impurity on the absorption spectrum and phase transitions in CsPbCl3 thin films
    (НТК “Інститут монокристалів” Національної академії наук України, 2018) Kovalenko, E. N.; Yunakova, O. N.; Yunakov, N. N.
    The absorption spectra of thin films of solid solutions CsPb(Cl1-xIx)3 0
  • Зображення мініатюри
    Публікація
    Exciton absorption spectra of KPb2Br5 thin films
    (Institute for Single Crystals, 2016) Kovalenko, E. N.; Kovalenko, V. V.; Yunakova, O. N.; Yunakov, N. N.
    The absorption spectrum of KPb2Br5 thin film of tetragonal (I) and monoclinic (II) structures were investigated in the spectral region of 2-6 eV and the temperature range 90-440K. It was found that KPb2Br5 (I) of the tetragonal structure irreversibly becomes in KPb2Br5(II) of the monoclinic structure when T = 293 K. It is found that low-frequency exciton excitations of KPb2Br5 (I, II) are localized in the sublattice, which contains ions Pb2+, and its are two-dimensional nature.
  • Зображення мініатюри
    Публікація
    Exciton absorption spectra of RbPb2Cl5 and Rb6Pb5Cl16 thin films
    (НТК “Інститут монокристалів” Національної академії наук України, 2019) Kovalenko, E. N.; Yunakova, O. N.; Yunakov, N. N.
    The absorption spectra of thin RbPb2Cl5 and Rb6Pb5Cl16 films were studied in the spectral range 2-6 eV and the temperature interval 90-500 K. A correlation was established between the absorption spectra and the crystal structure of the compounds. Excitons in both compounds are localized in a sublattice containing Pb2+ ions, and refer to excitons of the intermediate bond. An analysis of the temperature dependence of the half-width of exciton bands establishes a two-dimensional (2D) nature of the excitons in RbPb2Cl5 and three-dimensional (3D) in Rb6Pb5Cl16.
  • Зображення мініатюри
    Публікація
    Exciton absorption spectra of thin films of RbCu2Cl3 and Rb2Cu3Cl5 ternary compounds
    (2021) Kovalenko, E. N.; Yunakova, O. N.; Yunakov, N. N.
    The absorption spectra of RbCu2Cl3 and Rb2Cu3Cl5 thin films were studied in the 2–6 eV spectral and 90–450 K temperature ranges. The localization of excitons in 3–4CuCl structural elements of crystal lattice of compounds, three-dimensional nature of excitons in RbCu2Cl3 and two-dimensional nature of excitons in Rb2Cu3Cl5 were es-tablished. The exciton spectra of RbCu2Cl3 and Rb2Cu3Cl5 thin films were interpreted based on the transitions in the Cu+ ion.
  • Зображення мініатюри
    Публікація
    Exciton absorption spectrum of thin films of (CsxK1-x)2CuCl3 solid solutions.
    (2024) Kovalenko, E. N.; Yunakova, O. N.; Yunakov, N. N.
    The absorption spectra of thin films of (CsxK1-x)2CuCl3 0≤х≤1 (T=90K) solid solutions in the spectral range 2–6 eV were studied. According to the analysis of the spectra, the formation of two types of compounds was observed and studied: 1) compounds at x=0 and in the range of 0.4≤х≤1 which are isostructural to Cs2CuCl3 and K2CuCl3; 2) compounds at x=0.2 which are isostructural to CsCu2Cl3. The excitonic spectra of (CsxK1-x)2CuCl3 0≤х≤1compounds are caused by transitions in the Cu+ ion. The linear concentration dependences of the spectral position of exciton bands in both types of compounds confirm the localization of excitons in sublattices containing Cu+ ions.
  • Зображення мініатюри
    Публікація
    Exciton absorption spectrum of thin films of Cs1-xRbxCu2Cl3 solid solutions
    (Institute for Single Crystals, 2021) Kovalenko, E. N.; Yunakova, O. N.; Yunakov, N. N.
    The exciton absorption spectra of thin films of Cs1-xRbxPbCl3 solid solutions were studied in the spectral range 2 - 6 eV. The formation of solid solutions that are isostructural to CsCu2Cl3 was detected in the concentration range 0х0.6, the formation of solid solutions that are isostructural to RbCu2Cl3 was detected in the range 0.6<х≤1. A linear concentration dependences of the parameters of the exciton bands and the bandgap width were found in the intervals 0≤x≤0.6 and 0.6<х≤1. Exciton spectra of Cs1-xRbxCu2Cl3 0≤х≤1 solid solutions were interpreted based on the transitions in the Cu+ ion.
  • Зображення мініатюри
    Публікація
    Exciton absorption spectrum of thin films of ternary compounds in the CsCl-CuCl system
    (Фізико-технічний інститут низьких температур імені Б. І. Вєркіна, 2023) Kovalenko, E. N.; Yunakova, O. N.; Yunakov, N. N.
    The absorption spectra of thin films (CsCl)1-x(CuCl)x were studied at T=90K in the spectral range 2 – 6 eV. From the analysis of the spectra, the formation of CsCu2Cl3 and Cs2CuCl3 compounds in the CsCl – CuCl system was established. The Cs2CuCl3 compound is stable only in a vacuum; in air, it apparently decomposes into CsCu2Cl3 with a disordered crystal lattice and CsCl. The exciton spectrum of both compounds is interpreted on the basis of transitions in the Cu+ ion. A one-dimensional (1D) character of excitons in CsCu2Cl3 and a two-dimensional (2D) character in Cs2CuCl3 was established