2. Articole

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    Purification of ZnSe crystals from electrically active background impurities by ytterbium doping [Articol]
    (John Wiley & Sons, 2014) Radevici, Ivan; Sushkevich, Konstantin; Sirkeli, Vadim; Nedeoglo, Dmitrii; Nedeoglo, Natalia; Huhtinen, Hannu; Paturi, Petriina
    Hall coefficient, electrical conductivity, and electron mobility are investigated for n-ZnSe:Yb single crystals with high concentration of electrically active background impurities
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    In2O3-based thermoelectric materials: the state of the art and the role of surface state in the improvement of the efficiency of thermoelectric conversion [Articol]
    (MDPI, 2018) Korotcenkov, Ghenadii; Brinzari, Vladimir; Ham, Moon-Ho
    In this paper, the thermoelectric properties of In2 O3 -based materials in comparison with other thermoelectric materials are considered. It is shown that nanostructured In2 O3 Sn-based oxides are promising for thermoelectric applications at moderate temperatures. Due to the nanostructure, specific surface properties of In2 O3 and filtering effects, it is possible to significantly reduce the thermal conductivity and achieve an efficiency of thermoelectric conversion inaccessible to bulk materials. It is also shown that a specific surface state at the intergrain boundary, optimal for maximizing the filtering effect, can be achieved through (1) the engineering of grain boundary parameters, (2) controlling the composition of the surrounding atmosphere, and (3) selecting the appropriate operating temperature.
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    Growth and characterization of eu doped GaSe single crystals by X-ray diffraction and raman spectroscopy [Articol]
    (CEP USM, 2017) Untila, Dumitru; Evtodiev, Igor; Caraman, Iuliana; Kantser, Valeriu; Spalatu, Nicolae; Dmitroglo, Liliana; Evtodiev, Silvia; Spoială, Dorin; Rotaru, Irina; Gașin, Petru
    GaSe single crystals doped with Eu (0.025, 0.05, 0.5, 1.0 and 3.0 at%) were grown by Bridgman method using Ga, Se and Eu elementary components. The crystalline structure and vibration modes of the GaSe: Eu crystals lattice were studied by X-ray diffraction and Raman spectroscopy. Eu atoms arranged in the van der Waals space of GaSe: Eu crystals form Eu-Se valence bonds and restructure hexagonal lattice of GaSe leading to EuGa2Se4 crystallites formation. Defects generated by EuGa2Se4 crystallites lead to broadening and shifting of single phonon peaks present in Raman spectra towards shorter wavenumbers, and at the same time, activate the longitudinal optical vibrations of EuSe sublattice.