Search results for " GAP"
showing 10 items of 811 documents
Precision mass measurements of neutron-rich nuclei between N=50 and 82
2012
Our knowledge of binding energies of neutron-rich nuclei has experienced a major revision during the last five years due to the introduction of Penning-trap based mass measurements. New mass values for nearly 300 nuclides produced in fission with uncertainties of 10 keV or less have become available. The data produced at three Penning trap facilities at Jyvaskyla, CERN-ISOLDE and Argonne cover all isotopic chains from Ni to Pr, except iodine. In this talk some of this data is reviewed and applied using the mass differentials such as two-neutron binding energy and odd-even staggering to probe their sensitivity on changes in nuclear structure and on the strength of the N=82 shell gap and asso…
Solvability of nonlinear equations in spectral gaps of the linearization
1992
Keywords: strongle indefinite ; nonlinear Hill's equation Reference ANA-ARTICLE-1992-002doi:10.1016/0362-546X(92)90116-VView record in Web of Science Record created on 2008-12-10, modified on 2016-08-08
Comparative ab initio calculations of SrTiO3/BaTiO3 and SrZrO3/PbZrO3 (0 0 1) heterostructures
2016
Abstract Using a B3PW hybrid exchange–correlation functional within the density functional theory (DFT) we calculated from the first principles the electronic structure of BaTiO 3 /SrTiO 3 and PbZrO 3 /SrZrO 3 (0 0 1) interfaces. The optical band gap of both BaTiO 3 /SrTiO 3 and PbZrO 3 /SrZrO 3 (0 0 1) interfaces depends mostly from BaO or TiO 2 and SrO or ZrO 2 termination of the upper layer, respectively. Based on the results of our calculations we predict increase of the Ti–O and Zr–O chemical bond covalency near the SrTiO 3 /BaTiO 3 and SrZrO 3 /PbZrO 3 (0 0 1) interfaces as compared to the BaTiO 3 and PbZrO 3 bulk.
Ion track template technique for fabrication of ZnSe2O5 nanocrystals
2020
The work was performed under the grant of the Ministry of Education and Science of the Republic of Kazakhstan AP05134367 and Latvian grant lzp
Impact of Electrical Stress and Neutron Irradiation on Reliability of Silicon Carbide Power MOSFET
2020
International audience; The combined effects of electrical stress and neutron irradiation of the last generation of commercial discrete silicon carbide power MOSFETs are studied. The single-event burnout (SEB) sensitivity during neutron irradiation is analyzed for unstressed and electrically stressed devices. For surviving devices, a comprehensive study of the breakdown voltage degradation is performed by coupling the electrical stress and irradiation effects. In addition, mutual influences between electrical stress and radiative constraints are investigated through TCAD modeling.
Effect of annealing on Zn1−xCoxO thin films prepared by electrodeposition
2009
Polycrystalline thin films of Zn"1"-"xCo"xO with different cobalt (Co) content were grown on indium tin oxide (ITO) substrates by cathodic electrodeposition technique and subsequently annealed in air at 400^oC. The effect of annealing in their structural, optical and chemical properties has been characterized by X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Raman scattering and optical spectroscopy. Our measurements indicate that moderate annealing increases the crystal quality of the films. The films are highly transparent in the visible range and evidence an increase of the band gap and of the intensity of three typical Co absorptio…
Influence of F centres on structural and electronic properties of AlN single-walled nanotubes
2007
We analyse the influence of uncharged N vacancies (neutral F centres), created either under conditions of AlN nanotube growth or by its soft irradiation, on the atomic and electronic structure. Periodic one-dimensional (1D) density functional theory (DFT) calculations on models of defective single-walled nanotubes (SW NTs) allow us to analyse how NT chirality and concentration of F centres change their properties compared to the corresponding defect-free nanotubes. We have simulated reconstruction around periodically repeated F centres on 1 nm AlN SW NTs with armchair- and zigzag-type chiralities. To achieve the limit of an isolated vacancy for both chiralities, we have considered different…
SrTiO3 Nanotubes with Negative Strain Energy Predicted from First Principles
2011
On the basis of hybrid density functional theory calculations, we predict that the most energetically favorable single-walled SrTiO3 nanotubes with negative strain energy can be folded from SrTiO3 (110) nanosheets of rectangular morphology. Further formation of multiwalled tubular nanostructure with interwall distance of ∼0.46 nm yields an additional gain in energy of 0.013 eV per formula unit. (The formation energy of the most stable nanotube is 1.36 eV/SrTiO3.) Because of increase in the Ti–O bond covalency in the outer shells, SrTiO3 nanotubes can demonstrate an enhancement of their adsorption properties. Quantum confinement leads to a widening of the energy band gap of single-walled SrT…
Theoretical determination of the geometric and electronic structures of oligorylenes and poli(peri‐naphthalene)
1992
We present a theoretical investigation of the electronic structure of oligorylenes (from perylene to heptarylene, including also the naphthalene molecule) and their corresponding polymer poly(peri‐naphthalene) (PPN) using the nonempirical valence effective (VEH) method. The geometry of the unit cell used to generate the polymer is extrapolated from the PM3‐optimized molecular geometries of the longest oligorylenes. That geometry shows some bond alternation along the perimeter carbon chains and a bond length of ≊1.46 Å is calculated for the peri bonds connecting the naphthalene units. The VEH one‐electron energy level distributions calculated for oligorylenes are used to interpret the experi…
Theoretical study of the effect of substituent and backbone conformation on the electronic properties of symmetrically substituted poly(di‐n‐alkylsil…
1994
We present the results of ab initio 3‐21G∗ geometry optimizations and valence effective Hamiltonian (VEH) band structure calculations aimed at determining the evolution of the geometric and electronic (ionization potential, electron affinities, and band gaps) properties of all‐trans poly(dimethylsilane), poly(diethylsilane), poly(di‐n‐propylsilane), and poly(di‐n‐butylsilane) when increasing the size of the alkyl group. In the latter polymer, we have also studied the 7/3 conformation, in order to analyze the effect of the backbone conformation on the geometric and electronic structure. The VEH ionization potentials of all‐trans poly(di‐n‐alkylsilanes) are almost equal, and as experimental p…