Search results for "GST"

Pedagoģiskā prakse kā studentu topošo mūzikas skolotāju profesionālās kompetences veidošanās līdzeklis: augstskolas pedagoģija

1998

Al2O3 apvalka ietekme uz ZnO nanovadu morfoloģisko stabilitāti pie paaugstinātas temperatūras ZnO/Al2O3/MoS2 heterostrukturētās kodola-apvalka nanova…

2021

Al2O3 apvalka ietekme uz ZnO nanovadu morfoloģisko stabilitāti pie paaugstinātas temperatūras ZnO/Al2O3/MoS2 heterostrukturētās kodola-apvalka nanovadu sistēmās. Ozols A., darba vadītājs Dr. phys., vadošais pētnieks (LU CFI) Poļakovs B. Bakalaura darbs, 34 lappuses, 42 attēli, 37 literatūras avoti, 1 pielikums. Latviešu valodā. Šajā bakalaura darbā tika pētīts, kā alumīnija oksīda pārklājums ietekmē cinka oksīda nanovadu morfoloģisko stabilitāti pie paaugstinātas temperatūrās, molibdēna trioksīda slāni mēģinot pārvērst par molibdēna disulfīdu sēra tvaikos. Cinka oksīda nanovadu sintēzi veica ar ķīmiskā tvaika transporta reakciju. Alumīnija oksīda pārklājums tika uzklāts uz nanovadiem izmant…

Latvijas Vēstures Institūta Žurnāls. 2017, Nr. 4 (105)

2017

Valsts kultūrkapitāla fonds

Innovative electronic lithography using self-assembly films in order to modify material surfaces at nanometric scale

2013

The concept of electon beam decomposition has been developed in order to create smaller patterns than those achieved by conventional lithographic methods. This work aimed to go further about this concept through a separation of the involved mechanisms in order to better understand them and thus reach a better control of process.A device was designed and a protocol was defined where the first stage is the adsorption at cryogenic temperature of metal-carbonyl compounds. The adsorbate is then decomposed by a focused electron beam and fragmentation residues are removed through annealing allowing the deposit reorganization. The study of the different steps of the elaboration method was followed …

Raman study of the phase transitions sequence in pure WO3 at high temperature and in HxWO3 with variable hydrogen content

1999

Abstract An extensive investigation of the temperature dependence of Raman spectra has been carried out on WO 3 powders from room temperature to 800°C. In particular the orthorhombic-to-tetragonal phase transition occurring at about 740°C has been studied for the first time. The Raman active mode at 710 cm −1 of the orthorhombic phase disappears from the spectrum at temperature below the phase transition point and the Raman activity in the tetragonal phase results very low. A comparative study of hydrogenated tungsten bronzes H x WO 3 ( x ≤0.23), where the same transition sequence is driven by an increase of the proton concentration from x =0 to 0.23, reveals similar behaviour of the high f…

Local structure of nanosized tungstates revealed by evolutionary algorithm

2015

Nanostructured tungstates, such as CoWO4 and CuWO4, are very promising catalytic materials, particularly for photocatalytic oxidation of water. The high catalytic activity of tungstate nanoparticles partially is a result of their extremely small sizes, and, consequently, high surface-to-volume ratio. Therefore their properties depend strongly on the atomic structure, which differ significantly from that of the bulk material. X-ray absorption spectroscopy is a powerful technique to address the challenging problem of the local structure determination in nanomaterials. In order to fully exploit the structural information contained in X-ray absorption spectra, in this study we employ a novel ev…

3D superconducting hollow nanowires with tailored diameters grown by focused He+ beam direct writing

2020

Currently, the patterning of innovative three-dimensional (3D) nano-objects is required for the development of future advanced electronic components. Helium ion microscopy in combination with a precursor gas can be used for direct writing of three-dimensional nanostructures with a precise control of their geometry, and a significantly higher aspect ratio than other additive manufacturing technologies. We report here on the deposition of 3D hollow tungsten carbide nanowires with tailored diameters by tuning two key growth parameters, namely current and dose of the ion beam. Our results show the control of geometry in 3D hollow nanowires, with outer and inner diameters ranging from 36 to 142 …

Improvement in photocatalytic activity of stable WO3 nanoplatelet globular clusters arranged in a tree-like fashion: Influence of rotation velocity d…

2016

This study investigates the influence of controlled hydrodynamic conditions during anodization of tungsten (W) on the morphological, electrochemical and photocatalytic properties of a novel WO3 nanostructure: globular clusters of nanoplatelets associated in a tree-like fashion. For this purpose different techniques such as Field-Emission Scanning Electronic Microscopy (FE-SEM), electrochemical impedance spectroscopy (EIS) measurements, Mott-Schottky (M-S) analysis and photoelectrochemical water splitting tests have been carried out. Photoanodes obtained at 375 rpm showed the best photoresponse, much higher than that of conventional WO3 nanoplatelets, which can be ascribed to a noteworthy in…

Hierarchical Assembly of TiO2 Nanoparticles on WS2 Nanotubes Achieved Through Multifunctional Polymeric Ligands

2007

Thefunctionalization of nanotubes is required in order to bene-fit from their outstanding properties, as any application inmaterials and devices is hindered by processing and manipu-lation difficulties. Only the attachment of appropriate chem-ical functionalities on the nanotube surface allows tailoringof the properties for the respective applications. As an ex-ample, the enhancement of the nanotube solubility is onemajor task since most pristine nanotubes are insoluble inboth water and organic solvents. Thus, the improvement ofthe solubility by chemical functionalization is an importantconcept for synthetic chemists and materials scientists. Tai-loring of the surface chemical bonds might a…

Restricting Magnetic Interaction Pathways in Polyoxometalate Salts of Cationic Nitronyl Nitroxide Free Radicals

2004

Abstract : Salts 1 and 2 that combine the [W 6 O 19 ] 2- Lindqvist anion with the cationic nitronyl nitroxide (NN) free radicals p -MepyNN + and n Bu 3 NCH 2 NN + , respectively, have been synthesized and their structural and magnetic properties have been studied. Keywords: Nitroxide radicals, polyoxometalates, magnetism. Introduction Ferromagnetism based on purely organic materials has raised a lot of interest during the last decade [1]. Most of the studies have been performed with nitronyl nitroxide (NN) radicals due to their persistence, stability and ease of functionalization [2]. Bulk ferromagnetism in these compounds arises from ferromagnetic interactions between open-shell molecules …