Search results for "Application"
showing 10 items of 5559 documents
Time-Resolved Luminescence of Nanocrystalline Inorganic Complex Oxides
2007
Two types of complex nanosized oxides – cerium doped Y3Al5O12 (YAG) and CaWO4– have been studied by means of time-resolved luminescence spectroscopy. Comparative study of time-resolve luminescence characteristics of cerium doped YAG single crystal, nanopowders and nanoceramic as well as for CaWO4 macro- and nanocrystals has been done. Two components in the decay kinetic of Ce3+ related emission in YAG nanocrystals were detected and it was suggested that a different energy transfer rate to volume and surface Ce3+ ions takes place. It is shown that the segregation of Ce3+ ions near nanoparticles surface and/or dislocation lines plays a crucial role in degradation of light yield of cerium rela…
Nano composite membrane-electrode assembly formation for fuel cell-modeling aspects
2007
Long term stability is an essential requirement for fuel cell applications in automobile and stationary energy systems. In these systems the agglomeration of the catalyst nanoparticles is a well-known phenomenon which cannot be easily overcome or compensated for by re-designing the system. A direct result of this occurrence is the irreversible decrease of the electrochemical performance. Irregularities in electric field distribution are one root cause for migration and subsequent agglomeration of the catalyst nanoparticle. In this work, the impact of the electrode mechanical deformation on electric field distribution was studied using a computer modeling approach. Model of a Proton Exchange…
Microfabrication of hybrid fluid membrane for microengines
2015
International audience; This paper describes the microfabrication and dynamic characterization of thick membranes providing a technological solution for microengines. The studied membranes are called hybrid fluid-membrane (HFM) and consist of two thin membranes that encapsulate an incompressible fluid. This work details the microelectromechanical system (MEMS) scalable fabrication and characterization of HFMs. The membranes are composite structures based on Silicon spiral springs embedded in a polymer (RTV silicone). The anodic bonding of multiple stacks of Si/glass structures, the fluid filling and the sealing have been demonstrated. Various HFMs were successfully fabricated and their dyna…
Normal metal - insulator - superconductor thermometers and coolers with titanium-gold bilayer as the normal metal
2018
We have fabricated superconductor - insulator - normal metal - insulator - superconductor (SINIS) tunnel junctions in which Al acts as the superconductor, AlOx is the insulator, and the normal metal consists of a thin Ti layer (5 nm) covered with a thicker Au layer (40 nm). We have characterized the junctions by measuring their current-voltage curves between 60 mK and 750 mK. For comparison, the same measurements have been performed for a SINIS junction pair whose normal metal is Cu. The Ti-Au bilayer decreases the SINIS tunneling resistance by an order of magnitude compared to junctions where Cu is used as normal metal, made with the same oxidation parameters. The Ti-Au devices are much mo…
Riga Group’s recent results on laser applications for skin diagnostics
2021
Abstract The laser-related activities are reviewed of the Biophotonics Laboratory at UL Institute of Atomic Physics and Spectroscopy following the previous ICSQE-2018 conference. Four recent research projects are considered, including one EC Horizon-2020 project, two European Regional Development Fund (ERDF) projects and one project funded by the Latvian Council of Science (LCS). The projects are generally aimed at developing new optical methods and technologies for non-invasive in-vivo skin assessment to facilitate the early diagnostics of skin malformations (including cancers). Most of the projects explore novel approaches of camera-based biomedical imaging to the clinical diagnostics and…
Effect of the milling conditions on the degree of amorphization of selenium by milling in a planetary ball mill
2007
The effect of the milling parameters (rotation speed of the milling device and duration of milling) on the phase composition of the products of milling of fully crystalline selenium has been investigated. The milling was conducted using a planetary micromill and the phase composition of the milling products was determined by differential thermal analysis. It has been found that ball milling leads to the partial amorphization of the starting crystalline material. The content of amorphous phase in the milling products depends, in a rather complicated way, on the milling parameters. At the milling parameters adopted in the present study, the milling product was never fully amorphous. The compl…
Film-substrate lattice-engineering of HTS thin films
2008
Materials may show anisotropic properties on different crystal directions and this is also the case of High Temperature Superconductors (HTS). To take advantage of the materials anisotropy one concept of interest is 'orientation engineering' in thin films. This can be realized through the control of the film-substrate lattice relationship. Some examples in this regard are presented in this work and through comparative analysis we try to evaluate the viability of this approach and of he entcountered problems. It is expected that in the future this approach will generate new nano composite materials with new properties and effects leading to development of new devices with new or improved fun…
Efficiency investigation of a negative hydrogen ion beam production with the use of the gasdynamic ECR plasma source
2020
Abstract Negative hydrogen ion sources are of great demand in modern physics as injectors into accelerators and drivers for neutral beam injectors for fusion devices. It has been shown earlier that the use of the gasdynamic ECR discharge provides the opportunity to extract up to 80 mA/cm2 of negative ion current density. We studied experimentally the volumetric negative hydrogen ion production and vacuum ultraviolet emission in a gasdynamic ECR discharge. The high-density plasma was sustained by the pulsed 37 GHz / 100 kW gyrotron radiation in a magnetic configuration consisting of two consecutive simple mirror traps. The future prospects of the volumetric H− source based on the gasdynamic …
Investigation of the effect of intensive ball milling in a planetary ball mill on the thermal decomposition of cadmium carbonate and basic zinc carbo…
2007
The kinetics of thermal decomposition of cadmium carbonate CdCO3 and basic zinc carbonate ZnCO3?nZn(OH)2 and the effect of intensive milling in a planetary ball mill on its parameters, have been investigated. The values of the reaction heat and of the activation energies of thermal decomposition have been determined for both the compounds. Investigations of the thermal decomposition of the products of ball milling of investigated compounds revealed a slight effect of milling conditions on the reaction temperature and heat consumed during the thermal decomposition of ZnCO3?nZn(OH)2. No effect of ball milling on the thermal decomposition of CdCO3 has been found.
Mechanical properties of materials obtained via alkaline activation of illite-based clays of Latvia
2015
Materials has been synthesized in the temperature range from 60-100 °C from two illite based clays of Latvia under activation of KOH and NaOH solutions (4-6 M). Compressive strength and apparent porosity were measured. The effect of concentration of KOH and NaOH solutions on the material mechanical properties was investigated by means of infrared spectroscopy (IR). Compressive strength data of the materials showed that via such activation could obtain building materials with good quality.