Technetium Encapsulation by A Nanoporous Complex Oxide 12CaO•7Al2O3 (C12A7)

Technetium (99Tc) is an important long-lived radionuclide released from various activities including nuclear waste processing, nuclear accidents and atmospheric nuclear weapon testing. The removal of 99Tc from the environment is a challenging task, and chemical capture by stable ceramic host systems is an efficient strategy to minimise the hazard. Here we use density functional theory with dispersion correction (DFT+D) to examine the capability of the porous inorganic framework material C12A7 that can be used as a filter material in different places such as industries and nuclear power stations to encapsulate Tc in the form of atoms and dimers. The present study shows that both the stoichiometric and electride forms of C12A7 strongly encapsulate a single Tc atom. The electride form exhibits a significant enhancement in the encapsulation. Although the second Tc encapsulation is also energetically favourable in both forms, the two Tc atoms prefer to aggregate, forming a dimer.

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Migration Barriers and Evolution of Mechanical Properties of Oxide Nanoclusters Containing Helium

MRS Proceedings ◽

10.1557/opl.2015.180 ◽

2015 ◽

Vol 1743 ◽

Author(s):

Thomas Danielson ◽

Celine Hin

Keyword(s):

Mechanical Properties ◽

Density Functional ◽

Complex Oxide ◽

Functional Theory ◽

Ferritic Alloys ◽

Helium Concentration ◽

Migration Barriers ◽

Bcc Iron ◽

And Migration ◽

Trapping Sites

ABSTRACTHigh number densities of complex oxide nanoclusters in nanostructured ferritic alloys have been shown to act as effective trapping sites for the transmutation product helium. Density functional theory has been used to investigate the evolution of the mechanical properties of oxide nanoclusters as helium concentration increases. The migration barrier and migration path of helium in the oxide has also been tested in order to make a comparison with the barriers in BCC iron and offer insight to the helium trapping mechanisms of the oxides.

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Synthesis, Characterization, and Electronic Structures of Organically Templated Lead Halides with One- and Two-Dimensional Hybrid Structures, [(nbq)(PbI3)]n and {[(CH3)3NC2H4N(CH3)3]3(Pb6I18)}n

Australian Journal of Chemistry ◽

10.1071/ch07003 ◽

2007 ◽

Vol 60 (8) ◽

pp. 595 ◽

Cited By ~ 10

Author(s):

Hao-Hong Li ◽

Zhi-Rong Chen ◽

Liang-Qia Guo ◽

Kai-Ning Ding ◽

Jun-Qian Li ◽

...

Keyword(s):

Quaternary Ammonium ◽

Density Functional ◽

Crystal Packing ◽

Density Functional Theory Calculations ◽

Building Blocks ◽

Two Dimensional ◽

Functional Theory ◽

Structure Directing Agents ◽

Inorganic Framework ◽

Ammonium Compounds

Two new organically templated lead(ii) iodide complexes, [(nbq)(PbI3)]n 1 and {[(CH3)3NC2H4N(CH3)3]3(Pb6I18)}n 2, have been synthesized in the presence of aromatic and aliphatic quaternary ammonium compounds, N-(n-butyl)quinolinium (nbq+) and [(CH3)3NC2H4N(CH3)3]2+, respectively, acting as structure-directing agents. Both 1 and 2 consist of uncoordinated structure-directing agents and inorganic moieties bound to the organic structure-directing agents. In 1, an inorganic (PbI3–)n one-dimensional polyanion chain is built up by face-sharing of distorted PbI6 tetrahedra. The inorganic framework of 2 presents a two-dimensional arrangement that could be discussed in terms of [Pb3I10]4– building blocks. Static attractive interactions between organic countercations and inorganic moieties were revealed through the crystal packing. Density functional theory calculations indicate that 1 possesses semiconductor properties, tuned by the π-electrons of nbq+. In contrast, 2 is conductive in the direction of aliphatic quaternary ammonium moiety.

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Atomic Scale Simulation of the Effect of Hydrogen on Dislocations in Zr

MRS Proceedings ◽

10.1557/proc-653-z3.8 ◽

2000 ◽

Vol 653 ◽

Author(s):

C. Domain ◽

A. Legris

Keyword(s):

Nuclear Power ◽

Density Functional ◽

Power Plants ◽

Core Structure ◽

Atomic Scale ◽

Primary Coolant ◽

Functional Theory ◽

Screw Dislocations ◽

The Density Functional Theory ◽

Stacking Fault Energies

AbstractIn nuclear power plants, Zr–based cladding is corroded by the primary coolant. Concomitantly, it undergoes hydrogen pick–up which induces modifications of its mechanical properties, especially creep and recrystallization rates. Below 600K, the deformation in hcp Zr is partially controlled by screw dislocations, which due to their intricate core structure have reduced intrinsic mobility. Here, we address the possible hydrogen induced modifications of the core structure of screw dislocations. We used first–principle calculations based on the density functional theory to evaluate the interaction between hydrogen and screw dislocation cores and also to evaluate the hydrogen induced modifications of the prismatic and basal gamma surfaces. We show that the presence of hydrogen results in significant reductions of the stacking fault energies.

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Doping effects on the geometric and electronic structure of tin clusters

Physical Chemistry Chemical Physics ◽

10.1039/c9cp05124d ◽

2019 ◽

Vol 21 (44) ◽

pp. 24478-24488 ◽

Cited By ~ 1

Author(s):

Martin Gleditzsch ◽

Marc Jäger ◽

Lukáš F. Pašteka ◽

Armin Shayeghi ◽

Rolf Schäfer

Keyword(s):

Density Functional Theory ◽

Electronic Structure ◽

Density Functional ◽

Beam Deflection ◽

Functional Theory ◽

Doping Effects ◽

Depth Analysis ◽

Trajectory Simulations

In depth analysis of doping effects on the geometric and electronic structure of tin clusters via electric beam deflection, numerical trajectory simulations and density functional theory.

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