Search results for "Doping"
showing 10 items of 801 documents
Ab initiomodeling of sulphur doped TiO2nanotubular photocatalyst for water-splitting hydrogen generation
2012
In order to construct an efficient visible-light-driven TiO2 photocatalyst for water splitting applications, one has to perform improvements of its electronic structure. In this theoretical study we consider single-walled anatase TiO2 nanotubes having following morphologies: (101) 3-layered wall with chirality indexes (n,0) and (n,n), (101) 6-layered wall with (n,0) and (0,n), (001) 6-layered wall with (n,0) and (0,n), and (001) 9-layered wall with (n,0) and (0,n). The latter configuration occurs to be the most energetically stable, due to possessing negative strain energy. In our study the most stable 9-layered anatase (001) (0,n) nanotube has been doped with sulphur. According to obtained…
Transient and stable color centers in pure and Cu-doped LiNbO3
2003
The present work is devoted to investigation of stable and transient color centers that are induced by radiation and temperature in pure and Cu-doped LiNbO 3 single crystals. The transient changes of absorption of the crystals induced by pulsed electron beam (E=0.25 MeV) are studied in 0-5000 ns time range, as well as stable changes of absorption induced by reducing annealing and irradiation with γ-quanta, high energy electrons or fast reactor neutrons.
Should TiO2 nanostructures doped with Li+ be used as photoanodes for photoelectrochemical water splitting applications?
2017
[EN] Different TiO2 nanostructures, nanotubes and nanosponges, were obtained by anodization of Ti under stagnant and hydrodynamic conditions. Samples were doped with Li+ before and after annealing at 450 degrees C during 1 h. The nanostructures were characterized by different microscopy techniques: Field Emission Scanning Electron Microscopy (FE-SEM) and Raman Confocal Laser Microscopy. Additionally, Incident Photon-to-electron Conversion Efficiency (IPCE), photoelectrochemical water splitting and stability measurements were also performed. According to the results, TiO2 nanostructures doped before annealing present the worst photocurrent response, even if compared with undoped samples. On …
Size-selective incorporation of DNA nanocages into nanoporous antimony-doped tin oxide materials.
2011
A conductive nanoporous antimony-doped tin oxide (ATO) powder has been prepared using the sol-gel method that contains three-dimensionally interconnected pores within the metal oxide and highly tunable pore sizes on the nanoscale. It is demonstrated that these porous materials possess the capability of hosting a tetrahedral-shaped DNA nanostructure of defined dimensions with high affinity. The tunability of pore size enables the porous substrate to selectively absorb the DNA nanostructures into the metal oxide cavities or exclude them from entering the surface layer. Both confocal fluorescence microscopy and solution FRET experiments revealed that the DNA nanostructures maintained their int…
Effect of Zr4+Doping on the Electrical Properties of BaTiO3Ceramics
2011
The BaZrxTi1-xO3 for 0⩽x⩽15 ceramics were prepared by a conventional solid state reaction method and were determined by an X-ray diffraction (XRD) and scanning electron microscopy (SEM) for crystallographic, surface morphological and compositional studies. A single phase with perovskite structure was identified in the samples at room temperature. No significant impurities were detected in an EDS spectrum and the samples are in good stoichiometric ratio. The temperature dependence of electric conductivity was evaluated in the temperature range from 300 to 550 K for a selected frequency by a HP4284 LCR meter. The activation energy was calculated from the Arrhenius plots.
The effects of Pr3+ doping on the dielectric and photoluminescence properties of BaTi0.9(Yb0.5Nb0.5)0.1O3 ceramic
2019
Abstract The praseodymium Pr3+ doped BaTi0.9(Yb0.5Nb0.5)0.1O3 (BTYN01) ceramic, under low concentration (0.1%), was prepared by a conventional ceramic fabrication technique and its phase structure, microstructure, dielectric, vibrational and photoluminescence (PL) properties was studied. Both X-ray diffraction (XRD) and Raman studies confirmed the incorporation of Pr3+ into A-site lattice of BTYN01. The structure of Ba0.9985Pr0.001□0.0005Ti0.9(Yb0.5Nb0.5)0.1O3 (BTYN01-Pr) shows the coexistence of Pm 3 ¯ m -cubic symmetry (∼10%) and P4mm-tetragonal symmetry (∼90%) at room temperature. The dielectric study reveals that the maximum of the dielectric constant of BTYN01-Pr occurred at 283 K. The…
Atbildība par nelikumīgām darbībām sportā
2019
Šī darba temats ir atbildība par nelikumīgām darbībām sportā, konkrētāk, par manipulācijām ar sporta sacensībām un antidopinga noteikumu pārkāpumiem, skatoties uz faktu, ka par pirmo Krimināllikumā iekļauts atsevišķs pants, bet par dopinga lietošanu nav un kriminālatbildību iespējams piemērot tikai ļoti retos gadījumos. Tālākai tēmas analīzei būtiski izprast jēdzienu saturu, šo darbību praktisko izpausmi un ietekmi uz sportistu tiesībām, interesēm, kā arī uz sabiedrību kopumā. Bakalaura darba mērķis ir apskatīt minēto neatļauto rīcību aktualitāti Latvijā, regulējumu un tā atbilstību starptautiskajiem tiesību aktiem, kā arī regulējumu ārvalstīs, kurās par manipulācijām ar sporta sacensībām u…
Factors associated with potential doping behavior in Olympic-sailing: A gender-specific analysis
2019
BACKGROUND: Olympic-sailing is not contaminated with doping, and special efforts are needed to keep this sport free of doping. The aim of this study was to evaluate factors associated with potential doping behavior (PDB) in professional Olympic sailors. METHODS: The sample of participants were professional Olympic Laser class athletes (N.=80, 39 females ; all >18 years). Data were collected through previously validated questionnaires, utilizing sociodemographic-variables, sport- related- factors, and various factors of hesitation against doping (predictors), and PDB (criterion). To calculate the associations between predictors and the criterion, gender- stratified logistic regression models…
A theoretical investigation on the Cd doping of Cu-depleted CuInSe<inf>2</inf> materials
2011
Because of their outstanding characteristics and affordable price, polycrystalline thin film solar cells based on CuIn 1−x Ga x Se 2 (CIGS) absorber layer have emerged to be one of the most promising materials for photovoltaic applications [1–2]. To further enhance the efficiency of these solar cells much effort is spent on the in-depth investigation of the production methods. However, the effect of structural defects and dopants upon the macroscopic properties and morphology of epitaxially grown CIGS films is not yet fully understood [3]. More importantly, it is well established that the best cells can be prepared by growing the CIGS absorber layer under Cu-poor conditions [4]. Thus, it is…
Study of the use of methanol-filled Er-doped suspended-core fibres in a temperature-sensing ring laser system
2013
We report on an experimental/numerical investigation into the use of methanol-filled Er-doped suspended-core fibres (SCFs) in temperature-sensing ring laser systems. We have adopted a ring laser configuration that includes an Er-doped SCF as a temperature-dependent attenuator (TDA) with a step-index Er-doped fibre (EDF) as the laser active medium. The laser performance dependence on the temperature was measured both in continuous wave (CW) and transient regimes. CW laser output power and build-up time values are compared with those of similar laser systems based on other types of Er-doped PCFs or using other laser configurations. A notable variation of 0.73% °C−1 was achieved in CW operatio…