Isabelle Bardez
Chimie ParisTech
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Featured researches published by Isabelle Bardez.
Inorganic Chemistry | 2009
Damien Hudry; Aydar Rakhmatullin; Catherine Bessada; Isabelle Bardez; Florence Bart; Stéphane Jobic; Philippe Deniard
The synthesis of lanthanum phosphates in molten LiCl-KCL eutectic was chosen to address the preliminary treatment of chlorinated wastes containing fission products that are already present in a Li/Cl eutectic. The obtained monazite compound shows interesting properties to be considered as a good candidate to trap lanthanum for a long-time. The synthesis route based on LaCl(3) reaction with NH(4)H(2)PO(4) in a stoichiometric amount is a key point to obtain monazite as a pure phase. Hence, the salt composition is not modified during the synthesis reaction. The chemical reactivity of ammonium dihydrogenphosphate (NH(4)H(2)PO(4), hereafter abbreviated ADP) toward lanthanum chloride (LaCl(3)) in molten LiCl-KCl eutectic is probed by NMR spectroscopy to follow the formation of LaPO(4). Formally, a direct transformation of the two aforementioned precursors into LaPO(4), NH(4)Cl and HCl can be discarded on the basis of the low thermal stability of ADP. To shed some light on the formation of LaPO(4), in situ and ex situ NMR experiments were carried out on LiCl-KCl/LaCl(3)/ADP, as well as LiCl-KCl/ADP, KCl/ADP, and LiCl/ADP mixtures. First, the reactivity of the precursors in contact with the eutectic was studied from room temperature to 600 degrees C by means of (31)P, (35)Cl, and (139)La high temperature NMR. Second, ex situ room temperature magic angle spinning (MAS) and RadioFrequency driven recoupling (RFDR) (31)P solid-state NMR experiments were carried out on solid samples prepared in different conditions (i.e., temperature and atmosphere) and quenched at room temperature to identify frozen intermediate species in their metastable state. On the basis of this approach, we propose a model for the LaPO(4) formation based on a multistep mechanism which highlights the strong reactivity of ADP toward the alkaline salts but without final change in the composition of the solvent.
MRS Proceedings | 2003
Isabelle Bardez; Daniel Caurant; F. Ribot; Pascal Loiseau; J. L. Dussossoy; F. Villain; N. Baffier; C. Fillet
Local environments of rare earth ions are studied in a rare earth rich glass (Glass A wt%: 51.0SiO 2 -8.5B 2 O 3 -12.2Na 2 O-4.3Al 2 O 3 -4.8CaO-3.2ZrO 2 -16.0RE 2 O 3 with RE=Nd or La) developed for radioactive waste immobilisation. The aim is to determine the structural environment of rare earths in this glass according to their concentrations, and to study the influence of the peralkaline or peraluminous character of the glass on these environments. To achieve this objective, two series of glasses were prepared from Glass A. The first one contains variable amounts of rare earth oxide (from 0 to 30 wt% RE 2 O 3 ) and the second one is a series of peralkaline (R>50%) and peraluminous (R<50%) glasses, with R=([Na 2 O]+[CaO])/([Na 2 O]+[CaO] +[Al 2 O 3 ]) at fixed RE 2 O 3 contents (16 wt%). The coupling of characterisation methods such as EXAFS (extended x-ray absorption fine structure) spectroscopy at the neodymium L I I I -edge, optical absorption spectroscopy, Raman spectroscopy and 1 1 B, 2 9 Si and 2 7 Al MAS-NMR, enables discussion of several hypotheses concerning both the nature of rare earth neighbourhoods and the glassy network structure.
Microporous and Mesoporous Materials | 2009
Juliette van der Meer; Isabelle Bardez; Florence Bart; Pierre-Antoine Albouy; Gilles Wallez; Anne Davidson
Journal of Nuclear Materials | 2010
Daniel Caurant; Pascal Loiseau; Isabelle Bardez
Journal of Nuclear Materials | 2008
Damien Hudry; Isabelle Bardez; Aydar Rakhmatullin; Catherine Bessada; Florence Bart; Stéphane Jobic; Philippe Deniard
Journal of Non-crystalline Solids | 2011
Odile Majérus; Daniel Caurant; A. Quintas; Jean-Luc Dussossoy; Isabelle Bardez; Pascal Loiseau
Journal of Materials Science | 2007
Daniel Caurant; Pascal Loiseau; Isabelle Bardez; Christel Gervais
Journal of Materials Science | 2007
Daniel Caurant; Isabelle Bardez; Pascal Loiseau
Journal of Materials Science | 2007
Daniel Caurant; Isabelle Bardez; Pascal Loiseau
MRS Proceedings | 2002
Pascal Loiseau; Daniel Caurant; Isabelle Bardez; Odile Majérus; N. Baffier; C. Fillet