Experimental and modeling study of fission products and minor actinides extraction with N,N-dialkylamides

International audienc

Experimental and modeling study of ruthenium extraction with TBP

International audienc

Density and activity of perrhenic acid aqueous solutions at T= 298.15 K

International audiencePublished isopiestic molalities for aqueous HReO4 solutions at T = 298.15 K are completed. Binary data (variation of the osmotic coefficient and activity coefficient of the electrolyte in solution in the water) at T = 298.15 K for perrhenic acid HReO4 are determined by direct water activity and osmolality measurements. The variation of the osmotic coefficient of this acid in water is represented mathematically according to a model recommended by the National Institute of Standards and Technology and according to the specific interaction theory. The data are also used to evaluate the parameters of the standard three-parameters of Pitzer’s ion-interaction model, along with the parameters of Archer’s four-parameter extended ion-interaction model, to higher molalities than previously advised. Experimental thermodynamic data are well represented by these models. Density variations at T = 298.15 K are also established and used to express the activity coefficient values on both the molar and molal concentration scales

A macroscopic and molecular study for a complete description of technetium (VII) and uranium (VI) co-extraction mechanism with monoamides

International audienc

Etude expérimentale et modélisation des équilibres d'extraction des produits de fission par les monoamides

Responsable CEA : Sorel ChristianDirecteur universitaire : Dufrêche Jean-FrançoisNational audienc

Wet and Siconi® cleaning sequences for SiGe p-type metal oxide semiconductor channels

International audienceThe low temperature integration of new materials (such as SiGe channels for the holes) is mandatory in advanced metal oxide semiconductor field effect transistors (i.e. in 14 nm technology node devices and beyond). In this paper, we have investigated the removal of SiGe oxides prior to Selective epitaxial Growth of Si or SiGe:B in Sources/Drains regions. A very efficient removal of contaminants (C, F, O…) is mandatory if the H2 bake that precedes epitaxy is removed because of thermal budget constraints. As germanium is very reactive in the air, in-situ surface preparation schemes (conducted for instance in a Siconi® chamber) might be useful on SiGe surfaces. This way, the queue-time issues associated with “HF-Last” (HF/HCl follow by deionization water rinse) processes in single wafer wet cleaning tools are avoided. Germanium-rich SiGe layers (Si0.6Ge0.4) were used to characterize the native oxide removal efficiency of “HF-Last” and Siconi® processes. Then, a new surface preparation strategy was developed based on i) a wet chemical oxide formation followed by ii) a standard Siconi® process whose efficiency towards SiO2 has conclusively been demonstrated. Parallel Angle Resolved X-ray Photoelectron Spectroscopy was used to study the chemical composition of the native or chemical oxide and evaluate the efficiency of that treatment on carbon, germanium oxide and silicon oxide

Experimental and modelling study of ruthenium extraction with tri-n-butylphosphate in the purex process

International audienceRuthenium extraction by tri-n-butylphosphate (TBP) from nitric acid was studied and modelled in the conditions of the PUREX process. Experimental distribution ratios obtained for water, nitric acid and ruthenium were described with a physicochemical model based on the application of the mass action law on each extraction equilibrium and by taking into account deviations from thermodynamic ideal behaviour both in aqueous and organic phase using Mikulin and Sergievskii-Dannus equations. The best agreement between experimental and calculated ruthenium extraction isotherms was obtained by considering the formation of two complexes TBP$_2$RuNO (NO$_3$)$_3$(H$_2$O)$_2$ and TBP$_3$RuNO (NO$_3$)$_3$(H$_2$O)$_2$ ̅̅in organic phase. This model was implemented in the CEA-AREVA PAREX process simulation code and used to simulate ruthenium behaviour in a counter-current PUREX hot test performed in mixer-settlers

Density and activity of pertechnetic acid aqueous solutions at T = 298.15 K

International audienceThe previous isopiestic investigations of HTcO4 aqueous solutions at T = 298.15 K are believed to be unreliable, because of the formation of a ternary mixture at high molality. Consequently, published isopiestic molalities for aqueous HTcO4 solutions at T = 298.15 K were completed and corrected. Binary data (variation of the osmotic coefficient and activity coefficient of the electrolyte in solution in the water) at T = 298.15 K for pertechnetic acid HTcO4 were determined by direct water activity measurements. These measurements extend from molality m = 1.4 mol · kg−1 to m = 8.32 mol · kg−1. The variation of the osmotic coefficient of this acid in water is represented mathematically. Density variations at T = 298.15 K are also established and used to express the activity coefficient values on both the molar and molal concentration scale. The density law leads to the partial molar volume variations for aqueous HTcO4 solutions at T = 298.15 K, which are compared with published data

WET and SiconiTM cleaning sequences for SiGe pMOS channel

International audienc