Facultatea de Fizică şi Inginerie / Faculty of Physics and Engineering

Permanent URI for this communityhttps://msuir.usm.md/handle/123456789/7

Browse

Author: search.filters.author.Korotcenkov, GhenadiiStart date: 2021

Search Results

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    Current Trends in Nanomaterials for Metal Oxide-Based Conductometric Gas Sensors: Advantages and Limitations—Part 2: Porous 2D Nanomaterials [Articol]
    (2023) Korotcenkov, Ghenadii; Tolstoy, Valeri P.
    This article discusses the features of the synthesis and application of porous two-dimensional nanomaterials in developing conductometric gas sensors based on metal oxides. It is concluded that using porous 2D nanomaterials and 3D structures based on them is a promising approach to improving the parameters of gas sensors, such as sensitivity and the rate of response. The limitations that may arise when using 2D structures in gas sensors intended for the sensor market are considered.
  • Thumbnail Image
    Item
    Thermal transport evolution due to nanostructural transformations in ga-doped indium-tin-oxide thin films [Articol]
    (2021) Cocemasov, Alexandr; Brinzari, Vladimir; Jeong, Do-Gyeom; Korotcenkov, Ghenadii; Lee, Jong S.; Nika, Denis L.
    We report on a comprehensive theoretical and experimental investigation of thermal con- ductivity in indium-tin-oxide (ITO) thin films with various Ga concentrations (0–30 at. %) deposited by spray pyrolysis technique. X-ray diffraction (XRD) and scanning electron microscopy have shown a structural transformation in the range 15–20 at. % Ga from the nanocrystalline to the amorphous phase. Room temperature femtosecond time domain thermoreflectance measurements showed nonlinear decrease of thermal conductivity in the range 2.0–0.5 Wm−1 K−1 depending on Ga doping level. It was found from a comparison between density functional theory calculations and XRD data that Ga atoms substitute In atoms in the ITO nanocrystals retaining Ia-3 space group symmetry. The calculated phonon dispersion relations revealed that Ga doping leads to the appearance of hybridized metal atom vibrations with avoided-crossing behavior. These hybridized vibrations possess shortened mean free paths and are the main reason behind the thermal conductivity drop in nanocrystalline phase. An evolution from propagative to diffusive phonon thermal transport in ITO:Ga with 15–20 at. % of Ga was established. The suppressed thermal conductivity of ITO:Ga thin films deposited by spray pyrolysis may be crucial for their thermoelectric applications.
  • Thumbnail Image
    Item
    Metal oxides for biomedical and biosensor applications [Articol]
    (Elsevier, 2021) Mondal, Kunal; Korotcenkov, Ghenadii
    Metal Oxides for Biomedical and Biosensor Applications gives an in-depth overview of the emerging research in the biomedical and biosensing applications of metal oxides, including optimization of their surface and bulk properties. Sections cover biomedical applications of metal oxides for use in cell cultures, antibacterial and antimicrobial treatments, dental applications, drug delivery, cancer therapy, immunotherapy, photothermal therapy, tissue engineering, and metal oxide-based biosensor development. As advanced and biofunctionalized nano/micro structured metal oxides are finding applications in microfluidics, optical sensors, electrochemical sensors, DNA-based biosensing, imaging, diagnosis and analysis, this book provides a comprehensive update on the topic. Additional sections cover research challenges, technology limitations, and future trends in metal oxides and their composites regarding their usage in biomedical applications. © 2021 Elsevier Inc. All rights reserved.
  • Thumbnail Image
    Item
    Ozone sensing by In2O3 films modified with rh: Dimension effect [Articol]
    (MDPI, 2021) Korotcenkov, Ghenadii; Nehasil, Vaclav
    We considered the effect of coverage of the surface of In2O3 films with rhodium on the sensitivity of their electrophysical properties to ozone (1 ppm). The surface coverage with rhodium varied in the range of 0–0.1 ML. The In2O3 films deposited by spray pyrolysis had a thickness of 40–50 nm. The sensor response to ozone depends on the degree of rhodium coverage. This dependence has a pronounced maximum at a coverage of ~0.01 ML of Rh. An explanation is given for this effect. It is concluded that the observed changes are associated with the transition from the atomically dispersed state of rhodium to a 3D cluster state.
  • Thumbnail Image
    Item
    XPS study of Rh/In2O3 system [Articol]
    (Elsevier, 2021) Korotcenkov, Ghenadii; Brinzari, Vladimir; Nehasil, Vaclav
    The effect of surface modification of In2O3 films by rhodium atoms deposited by electron beam sputtering on the XP spectra is considered. The surface coverage with rhodium ranged from 0 to 0.1 ML. It was shown that the main changes in the XP spectra occur in the Rh3d region and are caused by the dimensional effect of rhodium particles. With an increase in the surface coverage with rhodium, Rh particles grow from an atomically dispersed state to relatively large clusters. As the particle size increases, its electronic structure tends to approach the state corresponding to the bulk Rh. Such a process is accompanied by a decrease in BE Rh3d5/2 by 0.3–0.6 eV, which behaviour depends on the surface structure of the used In2O3 films.
  • Thumbnail Image
    Item
    Thermal transport evolution due to nanostructural transformations in Ga-doped indium-tin-oxide thin films [Articol]
    (MDPI, 2021) Brinzari, Vladimir; Jeong, Do-Gyeom; Korotcenkov, Ghenadii; Vatavu, Sergiu; Lee, Jong S.; Nika, Denis; Cocemasov, Alexandr
    We report on a comprehensive theoretical and experimental investigation of thermal conductivity in indium-tin-oxide (ITO) thin films with various Ga concentrations (0–30 at. %) deposited by spray pyrolysis technique. X-ray diffraction (XRD) and scanning electron microscopy have shown a structural transformation in the range 15–20 at. % Ga from the nanocrystalline to the amorphous phase. Room temperature femtosecond time domain thermoreflectance measurements showed nonlinear decrease of thermal conductivity in the range 2.0–0.5 Wm−1 K−1 depending on Ga doping level. It was found from a comparison between density functional theory calculations and XRD data that Ga atoms substitute In atoms in the ITO nanocrystals retaining Ia-3 space group symmetry. The calculated phonon dispersion relations revealed that Ga doping leads to the appearance of hybridized metal atom vibrations with avoided-crossing behavior. These hybridized vibrations possess shortened mean free paths and are the main reason behind the thermal conductivity drop in nanocrystalline phase. An evolution from propagative to diffusive phonon thermal transport in ITO:Ga with 15–20 at. % of Ga was established. The suppressed thermal conductivity of ITO:Ga thin films deposited by spray pyrolysis may be crucial for their thermoelectric applications.