International Conference on Functional Materials and Nanotechnologies (FM&NT2012)
The International Conference Functional Materials and Nanotechnologies (FMN ferroics; multiscale and multiphenomenal material modeling and simulation 2. Nanotechnologies including progressive methods, technologies and design for investigation of nanoparticles, nanostructures, nanocomposites, thin films and coatings; 3. Energy including perspective materials and technologies for renewable and hydrogen energy, fuel cells, photovoltaics and developing diverse energy systems. A special section devoted to Organic Materials was organized to commemorate a long-time organizer of the FM&NT conference series, Dr. habil. phys, academician Inta Muzikante who passed away on 15 February 2012. The number …
Oxygen influence on luminescence properties of rare-earth doped NaLaF 4
Abstract Luminescence properties of erbium and europium doped NaLaF4 with different oxygen content have been studied. Vacuum ultraviolet (VUV) excitation luminescence spectroscopy technique has been applied by using synchrotron radiation excitation. It was found that oxygen impurity leads to significant degradation of Er3+ or Eu3+ emission under VUV excitation. The intensive O2−–Er3+ charge transfer excitation band has been detected from oxygen abundant NaLaF4 in the 150–165 nm spectral range. This band reveals a competing absorption mechanism in oxygen containing NaLaF4. It is clearly demonstrated that one reason for the Er3+ emission degradation in oxygen abundant NaLaF4 is strong suppres…
Hydrogen Adsorption in Zeolite Studied with Sievert and Thermogravimetric Methods
Natural clinoptilolite (mixture from clinoptilolite, quartz and muscovite) is activated with palladium and tested for hydrogen adsorption capability at temperatures RT - 200 o C. Thermogravimetric and volumetric methods showed that zeolite activated with palladium (1.25%wt) shows markedly high hydrogen adsorption capacity - up to 3 wt%. Lower amount of adsorbed hydrogen (~1.5 wt%) was found for raw zeolite and activated with higher amount of palladium sample. Hypothesis is proposed that the heating of zeolite in argon atmosphere forms and activates the pore structure in zeolite material, where hydrogen encapsulation (trapping) is believed to occur when cooling down to room temperature. An e…
Modified Graphene Sheet Stacks for Hydrogen Binding
Results are partially obtained using infrastructure of Lithuanian Energy Institute with support of COST Action MP1103 “Nanostructured materials for solid-state hydrogen storage”. Latvian National Research program IMIS2 is greatly acknowledged for financial support
Photo-Activity Research of Nano-Structured TiO2Layers
Titania with anatase structure is investigated due to its photo-active properties that can be used in the water photocatalysis applications and in the organic photovoltaic devices. In this work the anodization conditions are described to obtain stable thin film TiO2 layers formed from vertically oriented nanotubes with approximate height 358 nm, inner tube diameter 48 nm and wall thickness 20 nm, but centre to centre distance 100 nm. Annealed at 500 o C TiO2 layer mostly consists from oxide with anatase structure, though XRD spectroscopy shows rutile impurities as well. Obtained nanotube layers are sensitive mostly to UV light.
Guest Editorial
Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²
Comprehensive study on different crystal field environments in highly efficient NaLaF4:Er3+ upconversion phosphor
Abstract Complex fluorides, especially rare-earth doped NaREF 4 (RE = Y 3+ , La 3+ or Gd 3+ ), are promising materials for the upconversion luminescence mostly due to low phonon energy of their matrices and multisite nature of the crystalline lattice. Although multisite formation in hexagonal NaREF 4 structures has generally been proved, the actual number of the active sites in different structures varies from two (NaGdF 4 ) to seven (NaYF 4 ). The aim of this work has been to study multisite formation in NaLaF 4 :Er 3+ . For this purpose low-temperature site-selective spectroscopy measurements in hexagonal NaLaF 4 :Er 3+ have been performed. Excitation at different wavelengths correspondin…
Raman spectral identification of phase distribution in anodic titanium dioxide coating
Growing need for cleaner environment and energy production has brought about a hunt for perspective materials. One of such perspective materials is titanium dioxide (TiO2, titania) due to its chemical stability and photocatalytic properties. Titania can be synthesized through many methods but anodization process is one of the prevailing methods to produce high active surface nanostructured titania. Various anodization electrolytes produce different polymorphs of TiO2. Uniform phase distribution on the surface is crucial for higher photocatalytic activity. In this research, the influence of two electrolytes on polymorph phase distribution of TiO2 was investigated. Phase distribution correlat…
Catalyst activation of silica nano-based pore structure material for hydrogen storage
Silica based composite material with palladium synthesized by extractive-pyrolytic method is used for hydrogen absorption-desorption experiments. The results obtained of the study on dynamic sorption experiments showed that Pyrex glass based composite sample reaches high hydrogen concentration in the material quite fast. Thought silica gel based composite material rapidly reaches 1/2 of hydrogen load but afterwards the amount of hydrogenation increases slowly. The overall amount of absorbed hydrogen for Pyrex glass based material exceeds the amount of absorbed hydrogen by silica gel based material approximately 5.6 times.
Complex multilayer carbon structures for green energetics
The authors greatly acknowledge the IMIS2 project of the National Reform Programme of Latvia for financial support. The publication costs of this article were covered by the Estonian Academy of Sciences and the University of Tartu.
Photocatalytic activity of non-stoichiometric ZnFe2O4under visible light irradiation
Nanostructured zinc ferrites with different excess iron contents (ZnFe2+zO4, where z = 0.00, 0.05, 0.10 and 0.15) have been synthesized using the sol–gel auto-combustion method. The effect of excess iron on the structural, optical and visible light photocatalytic activity of zinc ferrite samples has been investigated. X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), x-ray magnetic circular dichroism (XMCD), Brunauer–Emmett–Teller theory, scanning electron microscopy (SEM), diffuse reflectance spectroscopy (UV–Vis) and photoluminescence spectroscopy were used to characterize the synthesized non-stoichiometric ZnFe2O4 powders. The XRD patterns demonstrated that the samples con…