Publications

We present a node-centered finite volume method for computing a representative range of eigenvalues and eigenvectors of the Schrodinger operator on a three-dimensional cylindrically symmetric bounded domain with mixed boundary conditions. The three-dimensional Schrodinger operator is reduced to a family of two-dimensional Schrodinger operators distinguished by a centrifugal potential. We consider a uniform, boundary conforming Delaunay mesh, which additionally conforms to the material interfaces. We study how the anisotropy of the effective mass tensor acts on the uniform approximation of the first K eigenvalues and eigenvectors and their sequential arrangement. There exists an optimal uniform Delaunay discretization with matching anisotropy with respect to the effective masses of the host material. For a centrifugal potential one retrieves the theoretically established first-order convergence, while second-order convergence is recovered only on uniform grids with an anisotropy correction. (C) 2013 Elsevier Inc. All rights reserved.

To study the suitability of using graphite as material for high-power targets for rare isotope production at the future Facility for Rare Isotope Beams (FRIB) in the USA and at the Facility for Antiproton and Ion Research (FAIR) in Germany, thin foils of polycrystalline graphite were exposed to 8.6-MeV/u Au ions reaching a maximum fluence of 1 x 10(15) ions/cm(2). Foil irradiation temperatures of up to 1800 degrees C were obtained by ohmic heating. In-situ monitoring of the electrical resistance of the graphite foils during and after irradiation provided information on beam-induced radiation damage. The rate of electrical resistance increase as a function of fluence was found to decrease with increasing irradiation temperature, indicating a more efficient annealing of the irradiation-produced defects. This is corroborated by the observation that graphite foils irradiated at temperatures below about 800 degrees C showed cracks and pronounced deformations, which did not appear on the samples irradiated at higher temperatures. (C) 2013 Elsevier B.V. All rights reserved.

Glass-ceramics containing Er3+/Yb3+ codoped CaF2 nanocrystals have been prepared by using the controlled crystallization above 650 degrees C of the (Yb3+/Er3+) codoped CaF2-SiO2 xerogels. X-ray diffraction and scanning electron microscopy data have revealed the formation of CaF2 nanoctystals of about 16 nm size. For pumping at 973 nm, this glass-ceramics shows, besides green and red up-conversion luminescence, violet (at similar to 408 nm) and near-ultraviolet emission (at similar to 380 nm). The mechanisms responsible for the upconversion luminescence are presented and discussed. The fluorescence lifetimes of the metastable levels responsible for violet, green and red luminescence are measured and their quantum efficiencies are estimated. (C) 2013 Elsevier B.V. All rights reserved.

A complex structure of four double layers of Ag / As2S3 has been deposited by Pulsed Laser Deposition method on a glass substrate. The effects of thermal annealing on the structural and optical properties were investigated. An effect of layer mixing has been evidenced.

We have prepared complex multilayer films based on Barium stearate. The multilayer samples have been deposited by the Langmuir-Blodgett technique. The complex multilayers were also deposited on body sensor. The sample was then subjected to the illumination with UV light. We observed changes in the resistivity of the multilayer during the illumination

Tungsten-tantalum composites with 10 and 20 at.% Ta were prepared by ball milling W powder with Ta fibers and by consolidating the milled materials with spark plasma sintering. The composites were implanted at room temperature with He (30 key with a fluence 5 x 10(21) at/m(2)) and/or D+ (15 keV with a fluence 5 x 10(21) at/m(2)) ion beams. The materials were studied by scanning and high-resolution transmission electron microscopy, both coupled with energy dispersive X-ray spectroscopy, and by X-ray diffraction, Rutherford backscattering spectrometry and nuclear reaction analysis. The microstructure observations revealed that the milling operation resulted in severe fragmentation of the Ta fibers. Furthermore, during the consolidation process the Ta phase acted as oxygen getter and reduced the W oxide present in the original material. The surface of the tungsten-tantalum composites implanted with D+ remained essentially unaltered, while the materials implanted with He+ evidenced blisters on the Ta-rich regions. D retention in the composites increased with He pre-implantation. (C) 2013 Elsevier B.V. All rights reserved.

This paper is an overview of the very first results obtained on pure tungsten (W) and oxide dispersed strengthened (ODS) W alloys produced by the Metal Injection Molding (MIM) technique for fusion applications. An extensive mechanical and physical characterization was performed, together with microstructural material investigation. The reported work was accomplished within the framework of the European Fusion Development Agreement work program. The main objective was to develop suitable tungsten grades for structural and armor divertor applications in the future DEMO fusion reactor. (C) 2013 Elsevier B.V. All rights reserved.

Double perovskite Sr2FeMoO6 was prepared by two ways consisting in sol gel technique and solid-state reaction method. The resulting powders from gel and mixed oxides precursors showed microstructures consisting of very fine grains (0.5-0.8 mu m) and a crystalline perovskite structure. The structural and microstructural properties of the double perovskite Sr2FeMoO6 powders as-prepared and ceramics were compared. Tetragonal Sr2FeMoO6 pellets were prepared from the two powders by spark plasma sintering at: 1000, 1100 and 1200 degrees C and then annealing at 1200 degrees C, 2 h in 5%H-2/Ar. The pellets presented different magnetic characteristics. The saturation magnetization of the samples prepared by sol-gel is close to those prepared by conventional synthesis method. (C) 2013 Elsevier Ltd. All rights reserved.

Sol-gel chemistry within the pores of a polycarbonate template membrane was used for the preparation of Eosin Y-SiO2 hybrid nano- and microrods, using tetraethylorthosilicate [TEOS, Si(OC2H5)(4)] as the precursor in the presence of trifluoroacetic acid (TFA) catalyst. The ethanolic solution of Eosin-Y was added to the silica sal to trap dye molecules inside the SiO2 gel network during the gelation. Structural and morphological characterization using scanning electron microscopy (SEM) and luminescence microscopy have shown the formation of rods with 200 nm and 1.2 mu m diameter and about 30 mu m length, exhibiting luminescence properties. Spectroscopic characterization has shown that the luminescence is due to Eosin-Y molecule in the xerogel porous network, surrounded by a solvation shell given mainly by the water. (C) 2013 Elsevier B.V. All rights reserved.