Browsing Zinātniskie raksti (CFI) / Scientific articles by Title

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    • Magnon and Phonon Excitations in Nanosized NiO 

      Sildos, I.; Puust, L.; Grabis, J.; Mironova-Ulmane, Nina; Kuzmin, Alexei (Sciendo, 2019)
      Single-crystal, microcrystalline and nanocrystalline nickel oxides (NiO) have been studied by Raman spectroscopy. A new band at ~200 cm-1 and TO-LO splitting of the band at 350–650 cm-1 have been found in the spectra ...

    • Manifestation of dipole-induced disorder in self-assembly of ferroelectric and ferromagnetic nanocubes 

      Zablotsky, Dmitry; Rusevich, Leonid L.; Zvejnieks, Guntars; Kuzovkov, Vladimir (Royal Society of Chemistry, 2019)
      The colloidal processing of nearly monodisperse and highly crystalline single-domain ferroelectric or ferromagnetic nanocubes is a promising route to produce superlattice structures for integration into next-generation ...

    • Matching the Directions of Electric Fields from Triboelectric and Ferroelectric Charges in Nanogenerator Devices for Boosted Performance 

      Šutka, Andris; Mālnieks, Kaspars; Lapčinskis, Linards; Timusk, Martin; Pudzs, Kaspars; Rutkis, Martins (Elsevier Inc., 2020)
      Embedding additional ferroelectric dipoles in contacting polymer layers is known to enhance the performance of triboelectricnanogenerator (TENG) devices. However, the influence of dipoles formed between the triboelectric ...

    • Measurement of Low Concentration of Nanosized Objects Suspended in a Liquid Medium 

      Merkulovs, Dmitrijs; Vilitis, Oskars; Kozlovs, V. (De Gruyter Open Ltd, 2018)
      The new optical scheme of refractometer with temperature stabilisation 10-2 °C is developed, which allows measuring a refractive index of the sample with accuracy not worse than 10-5; dependence of refraction index on ...

    • Mechanical reinforcement of electrospun poly(vinyl alcohol) by α‐FeOOH nanowires 

      Šutka, Anna; Järvekülg, Martin; Šutka, Andris; Heinmaa, Ivo; Mäeorg, Uno; Šmits, Krišjānis; Timusk, Martin (Society of Plastics Engineers (SPE), 2018)
      We report the mechanical performance of α‐FeOOH nanowire reinforced poly(vinyl alcohol) (PVA) composite nanofiber mat, fabricated using straightforward aqueous processing methods. Goethite (α‐FeOOH) nanocrystals have a ...

    • Membrane-less amphoteric decoupled water electrolysis using WO3 and Ni(OH)2 auxiliary electrodes 

      Vanags, Martins; Kulikovskis, Guntis; Kostjukovs, Juris; Jekabsons, Laimonis; Sarakovskis, Anatolijs; Smits, Krisjanis; Bikse, Liga; Sutka, Andris (Royal Society of Chemistry, 2022)
      Energy storage and delivery play a crucial role in the effective management of renewable power sources such as solar and wind. Hydrogen energy is proposed to be one of the major substitutes to fill the gap between the ...

    • Metal–Organic Frameworks (MOFs) Containing Adsorbents for Carbon Capture 

      Ansone-Bertina, Linda; Ozols, Viesturs; Arbidans, Lauris; Dobkevica, Linda; Sarsuns, Kristaps; Vanags, Edgars; Klavins, Maris (MDPI, 2022)
      In this study, new composite materials of montmorillonite, biochar, or aerosil, containing metal–organic frameworks (MOF) were synthesized in situ. Overall, three different MOFs—CuBTC, UTSA‐16, and UiO‐66‐BTEC—were used. ...

    • Methoxycarbazolyl-disubstituted dibenzofuranes as holes- and electrons-transporting hosts for phosphorescent and TADF-based OLEDs 

      Bucinskas, Audrius; Bezvikonnyi, Oleksandr; Gudeika, Dalius; Volyniuk, Dmytro; Grazulevicius, Juozas V. (Elsevier Ltd, 2020)
      In the search of universal host materials for organic light emitting diodes a new series of bipolar host materials containing methoxy-substituted carbazoles as the electron-donating and dibenzofuran as an electron-accepting ...

    • Micromechanical Properties of Gd3Ga5O12 Crystals Irradiated with Swift Heavy Ions 

      Aralbayeva, G.M.; Manika, Ilze; Karipbayev, Zh.; Suchikova, Y.; Kovachov, S.; Sugak, D.; Popov, Anatoli I. (Sumy State University, 2023)
      This study investigated the optical absorption and mechanical behavior of Gd3Ga5O12 (GGG) single crystals exposed to fast 84 Kr ions at fluences ranging from 1013 to 1014 ion/cm2. We observed that the optical absorption ...

    • Microwave-assisted synthesis and characterization of undoped and manganese doped zinc sulfide nanoparticles 

      Kuzmin, Alexei; Dile, Milena; Laganovska, Katrina; Zolotarjovs, Aleksejs (Elsevier, 2022)
      Undoped and Mn-doped ZnS nanocrystals were produced by the microwave-assisted solvothermal method and characterized by X-ray diffraction, photoluminescence spectroscopy and scanning electron microscopy with energy-dispersive ...

    • Modeling of the Lattice Dynamics in Strontium Titanate Films of Various Thicknesses: Raman Scattering Studies 

      Krasnenko, Veera; Platonenko, Alexander; Liivand, Aleksandr; Rusevich, Leonid L.; Mastrikov, Yuri A.; Zvejnieks, Guntars; Sokolov, Maksim; Kotomin, Eugene A. (MDPI, 2023)
      While the bulk strontium titanate (STO) crystal characteristics are relatively well known, ultrathin perovskites’ nanostructure, chemical composition, and crystallinity are quite complex and challenging to understand in ...

    • Modelling IR Spectra of Sulfonated Polyether Ether Ketone (SPEEK) Membranes for Fuel Cells 

      Vaivars, Guntars; Krūkle-Bērziņa, Kristīne; Markus, Madara (Scientific.Net, 2020)
      SPEEK (sulfonated polyether ether ketone) membranes have been prepared and characterized. The SPEEK membrane geometry and theoretical vibration spectra calculated using density functional theory (DFT) as depending from ...

    • Modification of free-volume defects in the GaS2–Ga2S3– CsCl glasses 

      Klym, H.; Calvez, L.; Popov, Anatoli I. (Springer, 2023)
      Modification of free-volume positron trapping defects in the GaS2–Ga2S3–CsCl chalcogenide glasses was studied using positron annihilation lifetime spectroscopy and Doppler broadening of annihilation radiation methods. It ...

    • Modification of polyoxymethylene for increased thermal resistance 

      Merijs Meri, Remo; Zicans, J.; Ābele, Agnese; Ivanova, Tatjana; Kalniņš, Märtiņš M.; Kundzinš, Kārlis (John Wiley and Sons Inc., 2017)
      Ternary nanocomposites, composed of polyoxymethylene (POM), ethylene octene copolymer and zinc oxide (ZnO), are prepared by melt compounding. The effects of two types of ethylene-octene copolymers, differing with α-octene ...

    • Modified graphene sheet stacks for hydrogen binding 

      Lesnicenoks, Peteris; Zemitis, Janis; Grinberga, Liga; Chikvaidze, George; Kleperis, Janis; Urbonavičius, Marius; Tačkute, Simona; Milčius, Darius (Kauno Technologijos Universitetas, 2017)
      Graphene sheet stacks were obtained using electrochemical exfoliation method. The morphology, distribution of elements and structure of the obtained samples were investigated using scanning electron microscopy, energy ...

    • Morphology Influence on Wettability and Wetting Dynamics of ZnO Nanostructure Arrays 

      Gerbreders, V.; Krasovska, M.; Mihailova, I.; Sledevskis, E.; Ogurcovs, A.; Tamanis, E.; Auksmuksts, V.; Bulanovs, A.; Mizers, V. (Walter de Gruyter, 2022)
      Changes in nanostructure morphology and size may result in very different surface wettability. In this research, the impact of different morphological parameters on the wetting dynamics of ZnO nanostructured layers is ...

    • Multifunctional derivatives of dimethoxy-substituted triphenylamine containing different acceptor moieties 

      Gudeika, Dalius; Bundulis, Arturs; Benhattab, Safia; Ben Manaa, Marwa; Berton, Nicolas; Bouclé, Johann; Tran Van, François; Schmalt, Bruno; Volyniuk, Dmytro; Rutkis, Martins; Grazulevicius, Juozas V. (Springer Nature Switzerland AG, 2020)
      Two compounds, having dimethoxy-substituted triphenylamino groups and fragments of cyanoacrylic acid or rhodanine-3-acetic acid were prepared and characterized. Their optical, photophysical, thermal, electrochemical, ...

    • Multimode Representation of the Magnetic Field for the Analysis of the Nonlinear Behavior of Solar Activity as a Driver of Space Weather 

      Popova, Elena; Popov, Anatoli I.; Sagdeev, Roald (MDPI, 2022)
      Estimating and predicting space weather is important to the space industry and space missions. The driver of space weather, especially near the Earth, is solar activity, the study of which is an important task. In particular, ...

    • Multimode time-dependent gyrotron equations for different time scales 

      Dumbrajs, Olgierd V.; Kalis, Harijs (American Institute of Physics Inc., 2017)
      Development of gyrotrons requires careful understanding of different regimes of gyrotron oscillations. For a long time, the gyrotron theory was developed assuming that the transit time of electrons through the interaction ...

    • Multisite formation in gadolinium doped SrF2 nanoparticles 

      Antuzevics, Andris; Kemere, Meldra; Krieke, Guna (Elsevier B.V., 2018)
      Gadolinium doped SrF2 nanoparticles have been synthesized by the precipitation method and characterized by site-selective optical spectroscopy and electron paramagnetic resonance (EPR) spectroscopy methods at cryogenic ...