Browsing Zinātniskie raksti (CFI) / Scientific articles by Title

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    • Unraveling the Structure and Properties of Layered and Mixed ReO3–WO3 Thin Films Deposited by Reactive DC Magnetron Sputtering 

      Polyakov, Boris; Butanovs, Edgars; Ogurcovs, Andrejs; Sarakovskis, Anatolijs; Zubkins, Martins; Bikse, Liga; Gabrusenoks, Jevgenijs; Vlassov, Sergei; Kuzmin, Alexei; Purans, Juris (American Chemical Society, 2022)
      Tungsten trioxide (WO3) is a well-known electrochromic material with a wide band gap, while rhenium trioxide (ReO3) is a “covalent metal” with an electrical conductivity comparable to that of pure metals. Since both WO3 ...

    • Untangling the controversy on Ce3+luminescence in LaAlO3crystals 

      Pejchal, Jan; Babin, Vladimir; Buryi, Maksym; Laguta, Valentyn; Hájek, František; Páterek, Juraj; Procházková-Prouzová, Lenka; Havlák, Lubomír; Czerneková, Vladimíra; Vaněček, Vojtěch; Doležal, Václav; Havlíček, Jan; Rubešová, Kateřina; Zemenová, Petra; Falvey, Alexandra; Král, Robert; Pankratov, Vladimir; Chernenko, Kirill (Royal Society of Chemistry, 2022)
      Aluminum perovskites represent an important group of promising scintillation materials with excellent proportionality and energy resolution, but due to difficulties in crystal growth not much attention has been paid to ...

    • Unveiling Molecular Changes in Water by Small Luminescent Nanoparticles 

      Labrador-Páez, Lucía; Jovanović, Dragana J.; Marqués, Manuel I.; Šmits, Krišjānis; Dolić, Slobodan D.; Jaqué, Francisco H.; Stanley, H. Eugene; Dramićanin, Miroslav D.; García-Solé, José Antonio; Haro-González, Patricia; Jaque, Daniel (Wiley-VCH Verlag, 2017)
      Nowadays a large variety of applications are based on solid nanoparticles dispersed in liquids—so called nanofluids. The interaction between the fluid and the nanoparticles plays a decisive role in the physical properties ...

    • Up-conversion luminescence of GdVO4:Nd3+/Er3+ and GdVO4:Nd3+/Ho3+ T phosphors under 808 nm excitation 

      Jovanović, Dragana J.; Gavrilović, Tamara V.; Dolić, Slobodan D.; Marinović-Cincović, Milena; Smits, Krisjanis; Dramićanin, Miroslav D. (Elsevier B.V., 2018)
      In recent years, there exists a tendency in research of up-conversion materials to shift excitation from 980 nm to shorter wavelengths. Here, in order to produce up-conversion luminescence emission of GdVO4-based materials ...

    • Upconversion luminescence in transparent oxyfluoride glass ceramics containing hexagonal NaErF4 

      Krieke, Guna; Antuzevics, Andris; Springis, Maris; Rogulis, Uldis (Elsevier, 2019)
      Transparent oxyfluoride glass ceramics containing hexagonal NaErF4 nanocrystals were synthesized by a heat treatment of a precursor glass obtained by the melt quenching technique. Combined X-ray diffraction (XRD) and ...

    • Upconversion luminescence in transparent oxyfluoride glass ceramics containing hexagonal NaErF4 

      Krieke, Guna; Antuzevics, Andris; Springis, Maris; Rogulis, Uldis (Elsevier B.V., 2019)
      Transparent oxyfluoride glass ceramics containing hexagonal NaErF4 nanocrystals were synthesized by a heat treatment of a precursor glass obtained by the melt quenching technique. Combined X-ray diffraction (XRD) and ...

    • Upconversion luminescence of a transparent glass ceramics with hexagonal Na(Gd,Lu)F4 nanocrystals 

      Krieke, Guna; Sarakovskis, Anatolijs; Springis, Maris (Elsevier B.V., 2017)
      Novel Er3+ doped transparent glass ceramics containing hexagonal Na(Gd,Lu)F4 nanocrystals were prepared from oxyfluoride glasses. The distribution of rare earth ions in the crystalline and glassy phase has been analyzed ...

    • Upconversion luminescence of Er3 +/Yb3 + and their role in the stabilization of cubic NaLaF4 nanocrystals in transparent oxyfluoride glass ceramics 

      Krieke, Guna; Sarakovskis, Anatolijs; Springis, Maris (Elsevier B.V., 2018)
      Novel Er3 + and Yb3 + doped transparent oxyfluoride glass ceramics containing NaLaF4 nanocrystals were prepared from oxyfluoride glasses with general composition of Na2O-NaF-LaF3-Al2O3-SiO2. The crystallization processes, ...

    • Use of site symmetry in supercell models of defective crystals: Polarons in CeO2 

      Évarestov, Robert A.; Gryaznov, D.; Arrigoni, Marco; Kotomin, Eugene A.; Chesnokov, Andrei; Maier, Joachim (Royal Society of Chemistry, 2017)
      In supercell calculations of defective crystals, it is common to place a point defect or vacancy in the atomic position with the highest possible point symmetry. Then, the initial atomic structure is often arbitrary distorted ...

    • UV light induced processes in pure and doped AlN ceramics 

      Trinkler, Laima; Trukhin, Anatoli; Cipa, Janis; Berzina, Baiba (Elsevier, 2021)
      AlN ceramics samples, pure and doped with Y2O3, Eu2O3 and GaN, and produced from the same AlN powder, were studied for photoelectric effect, photoluminescence spectra and kinetics and thermoluminescence under irradiation ...

    • Vacancy defects in Ga2O3: First-principles calculations of electronic structure 

      Usseinov, Abay; Koishybayeva, Zhanymgul; Platonenko, Alexander; Pankratov, Vladimir; Suchikova, Yana; Akilbekov, Abdirash; Zdorovets, Maxim; Purans, Juris; Popov, Anatoli I. (Multidisciplinary Digital Publishing Institute (MDPI), 2021)
      First-principles density functional theory (DFT) is employed to study the electronic structure of oxygen and gallium vacancies in monoclinic bulk β-Ga2 O3 crystals. Hybrid exchange– correlation functional B3LYP within the ...

    • Variation of Nonlinear Refraction and Three-Photon Absorption of Indium–Tin Oxide Quantum Dot Thin Films and Solutions in Near Infrared Range 

      Bundulis, Arturs; Berzina, Anete; Kim, Vyacheslav V.; Polyakov, Boris; Novikovs, Aleksandrs; Ganeev, Rashid A. (MDPI, 2023)
      We characterize the nonlinear optical properties of indium–tin oxide (ITO) quantum dots (QDs) in the IR range using the Z-scan method. We present results of three-photon absorption (3PA), third harmonic generation (3HG), ...

    • Vibrational analysis of paraelectric–ferroelectric transition of linbo3: An ab-initio quantum mechanical treatment 

      Gentile, Francesco Silvio; Diana, Rosita; Panunzi, Barbara; Caruso, Ugo; Platonenko, Alexander; Pascale, Fabien; Dovesi, Roberto (MDPI, 2021)
      The phase transitions between paraelectric (PE) and ferroelectric (FE) isomorph phases of LiNbO3 have been investigated quantum mechanically by using a Gaussian-type basis set, the B3LYP hybrid functional and the CRYSTAL17 ...

    • Water Splitting on Multifaceted SrTiO3 Nanocrystals: Calculations of Raman Vibrational Spectrum 

      Krasnenko, Vera; Rusevich, Leonid L.; Platonenko, Aleksander; Mastrikov, Yuri A.; Sokolov, Maksim; Kotomin, Eugene A. (MDPI, 2022)
      Various photocatalysts are being currently studied with the aim of increasing the photocatalytic efficiency of water splitting for production of hydrogen as a fuel and oxygen as a medical gas. A noticeable increase of ...

    • Water Splitting on Multifaceted SrTiO3 Nanocrystals: Computational Study 

      Sokolov, Maksim; Mastrikov, Yuri A.; Zvejnieks, Guntars; Bocharov, Dmitry; Kotomin, Eugene A.; Krasnenko, Veera (Multidisciplinary Digital Publishing Institute (MDPI), 2021)
      Recent experimental findings suggest that strontium titanate SrTiO3 (STO) photocatalytic activity for water splitting could be improved by creating multifaceted nanoparticles. To understand the underlying mechanisms and ...

    • WO3 as Additive for Efficient Photocatalyst Binary System TiO2/WO3 

      Knoks, Ainars; Kleperis, Janis; Bajars, Gunars; Grinberga, Liga; Bogdanova, Olga (Walter de Gruyter, 2021)
      Two different methods of synthesis of TiO2/WO3 heterostructures were carried out with the aim to increase photocatalytic activity. In this study, anodic TiO2 nanotube films were synthesized by electrochemical anodization ...

    • Wood and Black Liquor-Based N-Doped Activated Carbon for Energy Application 

      Plavniece, Ance; Volperts, Aleksandrs; Dobele, Galina; Zhurinsh, Aivars; Kruusenberg, Ivar; Kaprans, Kaspars; Knoks, Ainars; Kleperis, Janis (Multidisciplinary Digital Publishing Institute (MDPI), 2021)
      Fuel cells, batteries and supercapacitors are critical to meet the rising global demand for clean, sustainable energy. Biomass-derived activated carbon can be obtained with tailored properties to fulfil the extensive need ...

    • X-ray absorption and Raman spectroscopy studies of tungstates solid solutions ZncNi1-cWO4 (c=0.0-1.0) 

      Bakradze, Georgijs; Kalinko, Aleksandr; Kuzmin, Alexei (AIP Publishing, 2020)
      The influence of thermal disorder and static distortions on the local structure in microcrystalline solid solutions of tungstates ZncNi1-cWO4 with c = 0.0–1.0 was investigated using temperature-dependent (10–300 K) x-ray ...

    • X-ray absorption near edge spectroscopy of thermochromic phase transition in CuMoO4 

      Jonane, Inga; Cintins, Arturs; Kalinko, Aleksandr; Chernikov, Roman V.; Kuzmin, Alexei (Institute for Low Temperature Physics and Engineering, 2018)
      Thermochromic phase transition was studied in CuMoO4 using the Cu and Mo K-edge x-ray absorption spec-troscopy in the temperature range of 10-300 K. The hysteretic behavior has been evidenced from the tempera-ture dependence ...

    • X-ray excited luminescence of SrAl2O4:Eu,Dy at low temperatures 

      Liepina, Virginija; Millers, Donats; Smits, Krisjanis; Zolotarjovs, Aleksejs; Bite, Ivita (Elsevier B.V., 2018)