Characterization of Chemical Speciation in Ultrathin Uranium Oxide Layered Films

Abstract

A unique approach to detect chemical speciation and distribution on nanometer-scale nuclear materials has been achieved by the combination of neutron reflectometry and shell-isolated surface-enhanced Raman spectroscopy. Both surface and underlying layers of the uranium oxide materials were determined with angstrom-level resolution. Our results reveal that the UO(x) film is composed of three sublayers: an ∼38 Å thick layer of U(3)O(8) formed along the UO(x)/substrate interface; the adjacent sublayer consists of an ∼900 Å thick single phase of α-UO(3), and the top layer is γ-UO(3) with a thickness of ∼115 Å.

Environmental modeling of uranium interstitial compositions of non-stoichiometric oxides: experimental and theoretical analysis

“…Notwithstanding that our continues research interest for methodological MS developments and analytical implementation has been focused on elaboration of analytical protocols for environmental assessment mainly of organic contaminations, foodstuffs monitoring, and drugs of abuse analysis (Sukul et al 2010;Kusari et al 2009;Banerjee et al 2006;Smejkalova et al 2006;Frimmel et al 2002;Choi et al 2012;Spiteller 2012a, b, c, 2014;Lamshoeft et al 2011;Spiteller 1985Spiteller , 1987Spiteller , 2012Spiteller and Saiz-Jimenez 1990), the herein presented study is focused on uranium speciation in gas and condense phase, utilizing mass spectrometry and vibrational spectroscopy. Nevertheless of the generally higher method detection limits of the vibrational spectroscopic methods, the characteristic vibrational profile [ 970-900 cm -1 of m O=U=O as (m 3 ) stretching vibration (Best et al 1988;Guimbretiere et al 2012;Liang et al 2005;Mueller et al 2009;He et al 2002;Ivanova and Spiteller 2014) enable the utilization of the method for quantitative purposes. The full method validation applicable to real environmental problematic.…”

Probing Interfaces in Metals Using Neutron Reflectometry

“…The work of He et al illustrates the utility of NR for investigating imperfect uranium oxide films [75]. They deposited uranium oxide on silicon substrates (with a thin native layer of oxide) using a combination of DC magnetron and reactive sputtering.…”

A Review of Neutron Scattering Applications to Nuclear Materials

“…Using the neutron reflectometer SPEAR at LANSCE [202], He et al [203] characterized the surface of an ultrathin (<100 nm thickness) film of uranium oxide UO deposited on a quartz substrate. This technique allows to measure thicknesses and scattering characteristics of homogeneous layers.…”

“…Layer thicknesses of different urania phases as derived from differences in scattering length densities obtained in a neutron reflectometry experiment. The inset shows the neutron reflectivity data as circles with the model fit (after[203]). …”