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Instruments / Technical Area	Publication Details	Published
B18-Core EXAFS	Electrochemical evaluation of Pb, Ag, and Zn cyanamides/carbodiimides Jeethu Jiju Arayamparambil , Markus Mann , Xiaohui Liu , Maria Alfredsson , Richard Dronskowski , Lorenzo Stievano , Moulay Tahar Sougrati Acs Omega 4, 4339 - 4347 DOI: 10.1021/acsomega.8b02748 Open Access Show Abstract ▼ Abstract: PbNCN, Ag2NCN, and ZnNCN were tested as negative electrode materials for Li-ion batteries. A thorough analysis of the electrochemical mechanism by X-ray diffraction and X-ray absorption spectroscopy showed that, unlike transition metal carbodiimides, these compounds react with lithium via a two-step reaction, starting with conversion followed by alloying. The conversion reaction is highly irreversible for the three compounds, whereas the reversibility of the alloying reaction depends on the metal, that is, highly irreversible for PbNCN and Ag2NCN which contain the cyanamide group (N≡C–N2–) and more reversible for ZnNCN containing carbodiimide (−N═C═N–). In the case of the more covalent, cyanamide-type PbNCN and Ag2NCN, the conversion reaction occurs at a higher voltage compared to the more ionic, carbodiimide-type ZnNCN, correlated with the nature of bonding in the NCN group and in the phases themselves. Compared to transition metal carbodiimides, these materials show rather low performance, with no improvement in capacity as it would have been expected from the combination of conversion and alloying.	Feb 2019
B18-Core EXAFS	Electrochromic performances of nonstoichiometric NiO thin films H. Moulki , C. Faure , M. Mihelcic , A. Surca Vuk , F. Svegl , B. Orel , G. Campet , M. Alfredsson , A. V. Chadwick , D. Gianolio , A. Rougier Thin Solid Films DOI: 10.1016/j.tsf.2013.10.154 Show Abstract ▼ Abstract: Electrochromic (EC) performances of Ni3 + containing NiO thin films, called modified NiO thin films, prepared either by pulsed laser deposition or by chemical route are reported. When cycled in lithium based electrolyte, the comparison of the EC behavior of nonstoichiometric NiO thin films points out a larger optical contrast for the films synthesized by chemical route with the absence of an activation period on early electrochemical cycling due in particular to a larger porosity. Herein we demonstrate faster kinetics for modified NiO thin films cycled in lithium ion free electrolyte. Finally, X-ray absorption spectroscopy is used for a preliminary understanding of the mechanism involved in this original EC behavior linked to the film characteristics including their disorder character, the presence of Ni3 + and their porous morphology.	Nov 2013
I18-Microfocus Spectroscopy	Cycling of As, P, Pb and Sb during weathering of mine tailings: implications for fluvial environments D. Kossoff , K. A. Hudson-Edwards , W. E. Dubbin , M. Alfredsson , T. Geraki Mineralogical Magazine 76 (5), 1209-1228 DOI: 10.1180/minmag.2012.076.5.14 Diamond Proposal Number(s): [6543] Show Abstract ▼ Abstract: The weathering and oxidation of mine tailings has the potential to contaminate water and soil with toxic elements. To understand the mechanisms, extent and products of the long-term weathering of complex Bolivian tailings from the Cerro Rico de Potosí, and their effects on As, Pb, P and Sb cycling, three-year long laboratory column experiments were carried out to model 20 years of dry- and wet-season conditions in the Pilcomayo basin. Chemical analysis of the leachate and column solids, optical mineralogy, X-ray diffraction, scanning electron microscopy, electron probe microanalysis, microscale X-ray absorption near edge structure spectroscopy, Bureau Commun de Référence sequential extraction and water-soluble chemical extractions, and speciation modelling have shown that the weathering of As-bearing pyrite and arsenopyrite, resulted in a loss of 13–29% of the original mass of As. By contrast, Pb and Sb showed much lower mass losses (0.1–1.1% and 0.6–1.9%, respectively) due to the formation of insoluble Pb- and Sb(V)-rich phases, which were stable at the low pH (~2) conditions that prevailed by the end of the experiment. The experiment also demonstrated a link between the cycling of As, Sb, and the oxidation of Fe(II)-bearing sphalerite, which acted as a nucleation point for an Fe-As-Sb-O phase. Phosphorus was relatively immobile in the tailings columns (up to 0.3% mass loss) but was more mobile in the soil-bearing columns (up to 10% mass loss), due to the formation of soluble P-bearing minerals or mobilization by organic matter. These results demonstrate the influence of mine tailings on the mobility of P from soils and on the potential contamination of ecosystems with As, and strongly suggest that these materials should be isolated from fluvial environments.	Oct 2012

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