Search results for "Yttrium"
showing 10 items of 179 documents
Separation of fission products by the ion guide fed isotope separator, IGISOL
1987
Abstract The performance of the ion guide method in the on-line mass separation of fission products has been investigated. Activity was produced by bombarding nat. U targets with a beam of 20 MeV protons. All the mass chains from A = 95 through A = 120 have been scanned using conventional methods of nuclear spectroscopy. No chemical selectivity in the separation was observed; isotopes of highly nonvolatile elements from yttrium to palladium were produced with efficiencies equal to those for the more volatile ones. The boundary of known neutron-rich nuclides was reached throughout the mass region from A = 106 to A = 118. During the course of this preliminary study the new isotope 116 Rh was …
Ab initio modelling of titanium impurities in α-Fe lattice
2020
Abstract Reduced activation ferritic-martensitic (RAFM) as well as ferritic steels strengthened by yttrium oxide are considered as candidate materials for future fusion and advanced fission reactors. Addition of Ti during the manufacturing of the oxide dispersed strengthened (ODS) leads to the formation of yttrium titanium oxide particles, which size is smaller compared to yttrium oxide particles. This improves the mechanical properties and radiation resistance of the ODS steels. DFT calculations of Ti impurities have been performed to determine the factors contributing to the formation of the nanoparticles in α-Fe (bcc-Fe) based steels. The interaction energies between TiFe-OFe, TiFe-Ooct,…
ODS ferritic steels obtained from gas atomized powders through the STARS processing route: Reactive synthesis as an alternative to mechanical alloying
2018
Authors acknowledge ALBA synchrotron (Spain) for the provision of beamtime on the beam line BL22-CLAESS (Proposal 2016081797). Transmission electron microscopy observations were accomplished at Centro Nacional de Microscopía Electrónica, CNME-UCM. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. Financial support from Basque Government through the ELKARTEK ACTIMAT 2016 project is also acknowledged.
Modeling of yttrium, oxygen atoms and vacancies in γ-iron lattice
2011
Abstract Development of the oxide dispersion strengthened (ODS) steels for fission and fusion reactors requires a deep understanding of the mechanism and kinetics of Y 2 O 3 nanoparticle precipitation in the steel matrix. Therefore, it is necessary to perform a large-scale theoretical modeling of the Y 2 O 3 formation. In the current study, a series of first-principles calculations have been performed on different elementary clusters consisting of pair and triple solute atoms and containing: (i) the Y–Fe-vacancy pairs, (ii) the two Y atoms substituted for Fe lattice atoms and (iii) the O impurity atoms dissolved in the steel matrix. The latter is represented by a face-centered cubic γ-Fe si…
The role of yttrium and titanium during the development of ODS ferritic steels obtained through the STARS route: TEM and XAS study
2018
Abstract Oxide Dispersion Strengthened Ferritic Steels (ODS FS) are candidate materials for structural components in future fusion reactors. Their high strength and creep resistance at elevated temperatures and their good resistance to neutron radiation damage is obtained through extremely fine microstructures containing a high density of nanometric precipitates, generally yttrium and titanium oxides. This work shows transmission electron microscopy (TEM) and extended X-ray absorption fine structure (EXAFS) characterization of Fe-14Cr-2W-0.3Ti-0.24Y ODS FS obtained by the STARS route (Surface Treatment of gas Atomized powder followed by Reactive Synthesis), an alternative method to obtain O…
The shape transition in the neutron-rich yttrium isotopes and isomers
2007
Abstract Laser spectroscopy has been used to study 86–90,92–102Y and isomeric states of 87–90,93,96,97,98Y. Nuclear charge radii differences, magnetic dipole and electric quadrupole moments have been obtained. Information on the nature of the Z ≈ 40 , N ≈ 60 sudden onset of deformation has been derived from all three parameters. It is seen that with increasing neutron number from the N = 50 shell closure that the nuclear deformation becomes increasingly oblate and increasingly soft. At N = 60 a transition to a strongly deformed rigid prolate shape occurs but prior to this, although the nuclear deformation is increasing with N, a proportionate increase in softness is also observed.
First observation of nonyrast levels inZr103and level systematics ofN= 63 Sr, Zr, and Mo isotones
1996
The {beta} decay of the very-neutron-rich nucleus {sup 103}Y has been studied at the isotope separator IGISOL, allowing for the first time the observation of nonyrast levels in its daughter {sub 40}{sup 103}Zr{sub 63}. The level structure is similar to that of its isotones {sup 101}Sr and {sup 105}Mo, suggesting a large ground-state deformation of {beta}{approx_equal} 0.4. Level systematics allows for new level assignments in both {sup 103}Zr and {sup 105}Mo. {copyright} {ital 1996 The American Physical Society.}
Preparation and characterization of Ce:YAG-PMMA and Ce:YAG-PC composites for white LED
2015
Polymeric composites of lanthanide-doped materials were considered as potential candidates for the development of white LED. Ce:YAG-PMMA and Ce:YAG-PC composites were prepared by melt compounding. The characterization was performed using transmission electron microscopy, X-ray diffractometry, thermogravimetry and photoluminescence spectroscopy. The effect of filler quantity, in the range 0.1-5 wt.%, on the morphology, optical and thermal properties was investigated.
Lattice dynamics ofYVO4at high pressures
2010
We report an experimental and theoretical lattice-dynamics study of yttrium orthovanadate $({\text{YVO}}_{4})$ up to 33 GPa together with a theoretical study of its structural stability under pressure. Raman-active modes of the zircon phase are observed up to 7.5 GPa, where the onset of an irreversible zircon-to-scheelite phase transition is detected, and Raman-active modes in the scheelite structure are observed up to 20 GPa, where a reversible second-order phase transition occurs. Our ab initio total-energy calculations support that the second-order phase transition in ${\text{YVO}}_{4}$ is from the scheelite to the monoclinic M-fergusonite structure. The M-fergusonite structure remains u…
Lattice dynamics study of nanocrystalline yttrium gallium garnet at high pressure
2014
This work reports an experimental and theoretical lattice dynamics study of nanocrystalline Y3Ga5O12 (YGG) garnet at high pressures. Raman scattering measurements in nanocrystalline Tm3+-doped YGG garnet performed up to 29 GPa have been compared to lattice dynamics ab initio calculations for bulk garnet carried out up to 89 GPa. Good agreement between the theoretical vibrational modes of bulk crystal and the experimental modes measured in the nanocrystals is found. The contribution of GaO4 tetrahedra and GaO6 octahedra to the different phonon modes of YGG is discussed on the basis of the calculated total and partial phonon density of states. Symmetries, frequencies, and pressure coefficient…