Search results for "GaP"
showing 10 items of 1144 documents
El oficio de la resistencia. <i>Salvem</i> y <i>Viu al Cabanyal</i> como formas de contención del urbanismo neoliberal
2014
This article puts the spotlight on the resistance being displayed in the face of the expropriation and gentrification process currently affecting Valencia’s Cabanyal district (Spain). El Cabanyal is a district that has been left to the whim of town planners wielding megaproject/events cloaked in high-sounding rhetoric proclaiming excellence and competiveness. Specifically, we shall be looking closely at « Salvem el Cabanyal » as a response to the execution of the new Town Planning Plan, and « Viu al Cabanyal » as a means of putting a halt to progressive degradation. Salvem , a platform comprising several different entities, enjoys the support of an array of political, academic and social gr…
Skaidrojošās vārdnīcas Tezaurs.lv mobilie lietojumi
2019
Šodien, vairāk kā jebkad, mēs informāciju iegūstam mobilajās ierīcēs, tādēļ ir vērts padarīt maksimāli lielu daļu digitālās informācijas tām pieejamu. Tezaurs.lv ir lielākā atvērto datu latviešu valodas vārdnīca un tā korekti attēlojas tikai ierīcēs ar lieliem ekrāniem. Šī darba mērķis ir padarīt Tēzauru pieejamu un ērti lietojamu mobilajās ierīcēs. Darbā tiek analizēta vietnes lietotāju statistika, lai noteiktu prasības; rīkā Sketch izveidots interaktīvs saskarnes prototips; pašreizējā vietne pārveidota par reaģējošu; satvarā Adobe PhoneGap izveidota Android lietotne, kā arī Tēzaura bezsaistes dati pārveidoti par MOBI vārdnīcu lietojumam Kindle e-lasītājos, kas ir pirmā šāda veida vārdnīca…
Anomalous d-like surface resonances on Mo(110) analyzed by time-of-flight momentum microscopy.
2015
The electronic surface states on Mo(110) have been investigated using time-of-flight momentum microscopy with synchrotron radiation (hν=35 eV). This novel angle-resolved photoemission approach yields a simultaneous acquisition of the E-vs-k spectral function in the full surface Brillouin zone and several eV energy interval. (kx,ky,EB)-maps with 3.4 A(-1) diameter reveal a rich structure of d-like surface resonances in the spin-orbit induced partial band gap. Calculations using the one-step model in its density matrix formulation predict an anomalous state with Dirac-like signature and Rashba spin texture crossing the bandgap at Γ¯ and EB=1.2 eV. The experiment shows that the linear dispersi…
Effect of pressure on the structural properties and electronic band structure of GaSe
2007
The structural properties of GaSe have been investigated up to 38 GPa by monochromatic X-ray diffraction. The onset of the phase transition from the e-GaSe to a disordered NaCi-type structural motif is observed near 21 GPa. Using the experimentally determined lattice parameters of the layered e-phase as input, constrained ab-initio total energy calculations were performed in order to optimize the internal structural parameters at different pressures. The results obtained for the nearest-neighbor Ga-Se distance agree with those derived from recent EXAFS measurements. In addition, information is obtained on the changes of Ga-Ga and Se-Se bond lengths which were not accessible to a direct expe…
Physical Properties of Ba0.95Pb0.05TiO3+0.1%Co2O3
2012
The single-phase perovskite structure of the Ba0.95Pb0.05TiO3+0.1%Co2O3 ceramics was confirmed by the X-ray diffraction method. Microstructural studies revealed that the samples were of good quality and chemically homogeneous. The thermal behaviour of ceramics was studied using the in situ high-temperature X-ray synchrotron powder diffraction investigation. The energy gap of about 3.2 eV was estimated using a reflectance spectroscopy. Measurements showed the influence of Pb and Co on the character of phase transition in the BaTiO3 structure. The results were compared to the ones obtained for pure BaTiO3.
Density variations in liquid tellurium: Roles of rings, chains and cavities
2010
Liquid tellurium has been studied by density-functional/molecular-dynamics simulations at 560, 625, 722, and 970 K and by high-energy x-ray diffraction (HEXRD) at 763 K and 973 K. The HEXRD measurements agree very well with earlier neutron-scattering data of Menelle et al. The density maximum near the melting point (722 K) reflects the competition between twofold and threefold local coordination, which results in chain formation and changed ring statistics at lower $T$, and the variation with $T$ of the volume of cavities ($26--35\text{ }\mathrm{%}$ of the total). A higher-order gradient expansion of the exchange-correlation functional is needed to describe structural details. Changes in th…
Defects at the TiO2(100) surface probed by resonant photoelectron diffraction.
2006
We report photoelectron diffraction (PED) experiments of weakly sub-stoichiometric TiO 2 (100) rutile surfaces. Apart from standard core-level PED from the Ti-2p3/2 line, we have studied valence band PED from the defect induced Ti-3d states in the insulating band gap. For maximum yield, the latter were resonantly excited at the Ti-2p absorption edge. The PED patterns have been analyzed within the forward scattering approximation as well as by comparison with simulated PED patterns obtained in multiple scattering calculations. The analysis shows that the defect induced Ti-3d charge is mainly located on the second layer Ti atoms. © 2007 Elsevier B.V. All rights reserved.
<title>Mechanisms of holographic recording in amorphous semiconductor films</title>
1998
The mechanisms of holographic recording in (mainly chalcogenide) amorphous semiconductor films are reviewed including photoinduced structural changes, relaxational structural changes, recharging of localized states in the band gap, and photoinduced anisotropy. The holographic properties in these cases are compared. Different effects of hologram self-enhancement are also considered.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
High-pressure vibrational and optical study of Bi2Te3
2011
We report an experimental and theoretical lattice dynamics study of bismuth telluride (Bi2Te 3 )u p to 23 GPa together with an experimental and theoretical study of the optical absorption and reflection up to 10 GPa. The indirect bandgap of the low-pressure rhombohedral (R-3m) phase (α-Bi2Te 3) was observed to decrease with pressure at a rate of − 6m eV/GPa. In regard to lattice dynamics, Raman-active modes of α-Bi2Te 3 were observed up to 7.4 GPa. The pressure dependence of their frequency and width provides evidence of the presence of an electronic-topological transition around 4.0 GPa. Above 7.4 GPa a phase transition is detected to the C2/m structure. On further increasing pressure two …
Highly angular resolving beam separator based on total internal reflection
2019
We present an optical element for the separation of superimposed beams that only differ in angle. The beams are angularly resolved and separated by total internal reflection at an air gap between two prisms. As a showcase application, we demonstrate the separation of superimposed beams of different diffraction orders directly behind acousto-optic modulators for an operating wavelength of 800 nm. The wavelength as well as the component size can easily be adapted to meet the requirements of a wide variety of applications. The presented optical element allows one to reduce the lengths of beam paths and thus to decrease laser system size and complexity.