Oxidation of uranium mononitride

“…Using techniques similar to those described by Oi, Cleveland, and Bauer, [57,60,61], Paljevic, et al [62] also synthesized UN starting with pure uranium metal. The metal was first cleaned with ethanol and concentrated HNO 3 prior to drying in H 2 and being subjected to 250°C, where the metal was converted to UH 3 .…”

Section: Synthesis Of Uranium Mononitride (Un)mentioning

confidence: 99%

“…In order to form the desired mononitride, the U 2 N 3 was heated at 1200°C in vacuum for 1 hour resulting in UN (94.38 percent uranium and 5.54 percent nitrogen by weight). Paljevic, et al [62] then used this material to study the oxidation kinetics of UN. Olschewski, et al [17] used a very similar method to achieve similar results.…”

Section: Synthesis Of Uranium Mononitride (Un)mentioning

confidence: 99%

“…Accordingly, this hydride-nitride method to the synthesis of UN and the previous ball-milling method both use pure uranium metal as the starting material. The work in this section is adapted from a limited number of available published works describing the synthesis of UN from pure uranium metal [17,57,[60][61][62]71]. …”

Section: Hydride Prior To Nitridation Synthesis Route To Unmentioning

confidence: 99%

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Synthesis and Optimization of the Sintering Kinetics of Actinide Nitrides

Butt¹,

Jaques²

2009

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“…The oxidation of uranium mononitride in an oxygen atmosphere was systematically studied both experimentally and theoretically, as mentioned in many references [1][2][3]. It was demonstrated that oxygen impurities' incorporation even in little quantities into this fuel alters its physical properties (thermal conductivity,…); however for dinitrides and sesquinitrides, only some efforts have been devoted to these types of fuel.…”

mentioning

confidence: 99%

Adsorption and diffusion of oxygen atom on UN2(100) surface and subsurface: a density functional theory study (DFT and DFT + U)

et al. 2014

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In the present work, adsorption and diffusion of oxygen (O) atom on uranium dinitride (UN 2 ) is studied to map out the preferential UN 2 (100) surface site. The first principle method based on density functional theory (DFT) within the generalized gradient approximation PBE and the covariant version energy functional PBE ? U correction were used. The supercell approach and a coverage dependence of the adsorption structures and energetic were studied in detail for several monolayers' (ML) range. Potential energy surfaces (PES) corresponding to the interaction between O atom and UN 2 (100) on surface and subsurface for several sites and layers (Top U and Top N slabs) were calculated and favorable sites were identified with their maxima energy stable positions, which were then analyzed. For all positions, the PES show the same system behavior, when the O atom is sufficiently far from the UN 2 surface, and the energy of the system tends to the sum of free UN 2 slab and free oxygen atom energies. In return, when the distances decrease, strong interactions appear with presence of important potential wells. Calculation results showed that favored on-surface site for O atom adsorption were found to be near the bridge one for the UN (Top U slab) corresponding to five layers, uranium terminated and top one for (Top N slab) corresponding to six layers nitrogen terminated, the maximum system energy is situated at a position of about 1.2 and 1.5 Å from the surface for the two layers types calculations respectively. For subsurface results, only Top N presents a favorable incorporation site at the hollow position and the penetration of O atom is about -0.5 Å from the surface. DFT ? U study confirms all the results obtained by DFT calculations; that is, the maxima site positions for oxygen atom and the adhesion energy values per atom are of the same order of magnitudes. The adsorption energy per oxygen atom and the mean distance from the top surface gradually decrease with the coverage of O atoms for both on-surface cases, Top U and Top N slabs, with oxygen occupying the favorable site. For the Top N slab hollow site, the incorporation of oxygen through the surface becomes effective from a coverage of 3/8 ML with an encrustation of about -0.3 Å .

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Oxidation of uranium mononitride

Cited by 38 publications

References 7 publications

First Principles Simulations on Surface Properties and Oxidation of Nitride Nuclear Fuels

First Principles Simulations on Surface Properties and Oxidation of Nitride Nuclear Fuels

Synthesis and Optimization of the Sintering Kinetics of Actinide Nitrides

Adsorption and diffusion of oxygen atom on UN2(100) surface and subsurface: a density functional theory study (DFT and DFT + U)

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