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Chen P.H.,State Key Laboratory for Surface Physics and Chemistry | Wang X.L.,China Academy of Engineering Physics | Lai X.C.,State Key Laboratory for Surface Physics and Chemistry | Li G.,State Key Laboratory for Surface Physics and Chemistry | And 2 more authors.
Journal of Nuclear Materials | Year: 2010

Based on the Chen-Möbius lattice inversion and a series of pseudopotential total-energy curves, interionic pair potentials for UN were derived. By means of molecular dynamic (MD), we have examined this interionic potentials. Comparing with the experimental data, the thermal expansion coefficient and the compressibility were well reproduced by this potentials. © 2010 Elsevier B.V.


Zhang Y.,State Key Laboratory for Surface Physics and Chemistry | Meng D.,State Key Laboratory for Surface Physics and Chemistry | Xu Q.,State Key Laboratory for Surface Physics and Chemistry | Zhang Y.,China Academy of Engineering Physics
Journal of Nuclear Materials | Year: 2010

Pulsed laser nitriding offers several advantages such as high nitrogen concentration, low matrix temperature, fast treatment, simple vacuum chamber and precise position control compare to ion implantation, which is favorable for radioactive material passivation. In this work, uranium metal was nitrided using an excimer laser for the first time. The nitrided layers are characterized by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The nitride layer is composed mainly of UN and U2N3 and depends on nitriding process. The amount of nitride increases with energy density and pressure. The irradiated area has a wavy structure which increases the roughness, while scratches and asperities caused by sand paper polishing were eliminated. Scan speed has a profound influence on the nitride layer, at low speed U2N3 is more likely to form and the nitride layer tends to crack. XPS analysis shows that nitrogen has diffused into interior, while oxygen is only present on the surface. Ambient and humid-hot corrosion tests show the nitrided sample has good anticorrosion property. © 2009 Elsevier B.V. All rights reserved.


Shi H.,CAS Beijing Institute of Applied Physics And Computational Mathematics | Shi H.,CAS Institute of Semiconductors | Chu M.,State Key Laboratory for Surface Physics and Chemistry | Zhang P.,CAS Beijing Institute of Applied Physics And Computational Mathematics | Zhang P.,Beijing University of Technology
Journal of Nuclear Materials | Year: 2010

We perform first-principles calculations of electronic structure and optical properties for UO 2 and PuO 2 based on the density functional theory using the generalized gradient approximation (GGA) + U scheme. The main features in orbital-resolved partial density of states for occupied f and p orbitals, unoccupied d orbitals, and related gaps are well reproduced compared to experimental observations. Based on the satisfactory ground-state electronic structure calculations, the dynamical dielectric function and related optical spectra, i.e., the reflectivity, adsorption coefficient, energy-loss, and refractive index spectrum, are obtained. These results are consistent with the available experiments. © 2010 Elsevier B.V. All rights reserved.

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