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Catherine Beaucaire - One of the best experts on this subject based on the ideXlab platform.

  • adsorptIon of strontium and caesium onto an na illite and na illite na smectite mixtures implementatIon and applicatIon of a multi Site Ion exchange model
    Applied Geochemistry, 2018
    Co-Authors: Brice Siroux, Aubery Wissocq, Catherine Beaucaire, Christelle Latrille, Cristina Petcut, Jordan Calvaire, Michel Tabarant, Marc F Benedetti, Pascal E Reiller
    Abstract:

    Abstract The applicatIon of a multi-Site Ion-exchange (MSIE) model to the predictIon of contaminant behaviour onto soils or sediments requires a coherent adsorptIon database. Following the same approach exposed in preceding works on smectite (Siroux et al., Appl. Geochem. 87, 167; Wissocq et al., Appl. Geochem., 93, 167), a database is here implemented to allow modelling the adsorptIon of radIonuclides 90Sr and 137Cs onto Na-illite, one of the major clay mineral encountered in the terrestrial environment. This database allows describing the adsorptIon properties of Sr2+ and Cs+ competing with major catIons H+ — considered as the reference catIon — and Na+ onto an Na-illite. To obtain the adsorptIon Site capacities and selectivity coefficients of illite Sites for Na+ towards H+, a saturatIon curve of Na+ on Na-conditIoned illite was acquired. AdsorptIon isotherms issued from literature have been reinterpreted using the MSIE model to obtain the adsorptIon properties of Sr2+ and Cs+ onto purified and Na-conditIoned illite. Afterwards, the predictability and robustness of the database were verified simulating experimental adsorptIon of Sr2+ and Cs+ onto Na-illite/Na-smectite mixtures.

  • applicatIon of the multi Site Ion exchanger model to the sorptIon of sr and cs on natural clayey sandstone
    Applied Geochemistry, 2017
    Co-Authors: Aubery Wissocq, Catherine Beaucaire, Christelle Latrille
    Abstract:

    Abstract To ensure the environmental monitoring of nuclear Sites, sorptIon models enabling the predictIon of contaminant migratIon (such as 90Sr and 137Cs) in soils, sediments and aquifers need to be developed. This paper aims 1) at developing a database containing the sorptIon properties of the pure mineral phases commonly encountered in natural environments and 2) at using this database in a multi-Site Ion exchange model to be applied on natural sediments. In additIon to some raw adsorptIon data issued from literature, different sorptIon experiments of Sr and Cs, on pure illite and smectite, in competitIon with calcium were carried out, as a functIon of pH and as well as concentratIons of Sr and Cs. These sorptIon data were interpreted using a multi-Site Ion-exchange model and contributed to the elaboratIon of a thermodynamic database gathering the retentIon properties of illite and smectite (Site capacities and selectivity coefficients) towards Cs+, Sr2+, H+ and Ca2+. A multi-Site Ion exchange model based on the mixture of pure mineral phases (illite and smectite) was successfully applied to simulate the Sr and Cs behavior in a natural clayey sandstone, indicating that the additivity of retentIon properties of the minerals constituting the sediment can be verified.

  • impact of the solutIon Ionic strength on strontium diffusIon through the callovo oxfordian clayrocks an experimental and modeling study
    Applied Geochemistry, 2015
    Co-Authors: Sebastien Savoye, Catherine Beaucaire, B Grenut, A Fayette
    Abstract:

    DiffusIon of catIons in clayrocks is widely investigated, because deep clay-rich formatIons are currently considered as one of the potential host rocks for radioactive waste repositories. However, several authors have already reported that sorbing catIons seem to diffuse at rates larger than those predicted by a simple pore diffusIon model from their sorptIon coefficients and from the diffusive flux of non-sorbing water tracers. This process has been attributed to the migratIon of catIons within the electrical double layer, next to the mineral surfaces, called the surface diffusIon phenomenon. The aim of this work was to verify whether this “enhanced” catIon diffusIon compared to neutral species was observed for strontium and, if so, to what extent this effect might vary with the salinity of the synthetic solutIons. These questIons were addressed by performing batch sorptIon, through-diffusIon and out-diffusIon experiments on rock samples from the Callovo-Oxfordian claystone formatIon (France). The results showed that there was a good agreement of the distributIon ratios (RD) determined on crushed and intact rocks by batch and through-diffusIon methods with a RD decrease related to the increase of the sodium concentratIon, a sorptIon competitor. Such a trend was also well reproduced by means of a geochemical modeling based on the multi-Site Ion exchange (MSIE) theory. Moreover, the “enhanced” diffusIon for strontium was clearly observed in this study: the Sr diffusive flux was almost five times higher than that for HTO in the cell with the lowest Ionic strength, and diminished to less than 1.5 times in the cell with the highest Ionic strength. The evolutIon of the Sr diffusive flux with the Ionic strength was qualitatively reproduced by a surface diffusIon model, based on the concept of relative diffusive mobility or mobile fractIon.

Christelle Latrille - One of the best experts on this subject based on the ideXlab platform.

  • adsorptIon of strontium and caesium onto an na illite and na illite na smectite mixtures implementatIon and applicatIon of a multi Site Ion exchange model
    Applied Geochemistry, 2018
    Co-Authors: Brice Siroux, Aubery Wissocq, Catherine Beaucaire, Christelle Latrille, Cristina Petcut, Jordan Calvaire, Michel Tabarant, Marc F Benedetti, Pascal E Reiller
    Abstract:

    Abstract The applicatIon of a multi-Site Ion-exchange (MSIE) model to the predictIon of contaminant behaviour onto soils or sediments requires a coherent adsorptIon database. Following the same approach exposed in preceding works on smectite (Siroux et al., Appl. Geochem. 87, 167; Wissocq et al., Appl. Geochem., 93, 167), a database is here implemented to allow modelling the adsorptIon of radIonuclides 90Sr and 137Cs onto Na-illite, one of the major clay mineral encountered in the terrestrial environment. This database allows describing the adsorptIon properties of Sr2+ and Cs+ competing with major catIons H+ — considered as the reference catIon — and Na+ onto an Na-illite. To obtain the adsorptIon Site capacities and selectivity coefficients of illite Sites for Na+ towards H+, a saturatIon curve of Na+ on Na-conditIoned illite was acquired. AdsorptIon isotherms issued from literature have been reinterpreted using the MSIE model to obtain the adsorptIon properties of Sr2+ and Cs+ onto purified and Na-conditIoned illite. Afterwards, the predictability and robustness of the database were verified simulating experimental adsorptIon of Sr2+ and Cs+ onto Na-illite/Na-smectite mixtures.

  • applicatIon of the multi Site Ion exchanger model to the sorptIon of sr and cs on natural clayey sandstone
    Applied Geochemistry, 2017
    Co-Authors: Aubery Wissocq, Catherine Beaucaire, Christelle Latrille
    Abstract:

    Abstract To ensure the environmental monitoring of nuclear Sites, sorptIon models enabling the predictIon of contaminant migratIon (such as 90Sr and 137Cs) in soils, sediments and aquifers need to be developed. This paper aims 1) at developing a database containing the sorptIon properties of the pure mineral phases commonly encountered in natural environments and 2) at using this database in a multi-Site Ion exchange model to be applied on natural sediments. In additIon to some raw adsorptIon data issued from literature, different sorptIon experiments of Sr and Cs, on pure illite and smectite, in competitIon with calcium were carried out, as a functIon of pH and as well as concentratIons of Sr and Cs. These sorptIon data were interpreted using a multi-Site Ion-exchange model and contributed to the elaboratIon of a thermodynamic database gathering the retentIon properties of illite and smectite (Site capacities and selectivity coefficients) towards Cs+, Sr2+, H+ and Ca2+. A multi-Site Ion exchange model based on the mixture of pure mineral phases (illite and smectite) was successfully applied to simulate the Sr and Cs behavior in a natural clayey sandstone, indicating that the additivity of retentIon properties of the minerals constituting the sediment can be verified.

Aubery Wissocq - One of the best experts on this subject based on the ideXlab platform.

  • adsorptIon of strontium and caesium onto an na illite and na illite na smectite mixtures implementatIon and applicatIon of a multi Site Ion exchange model
    Applied Geochemistry, 2018
    Co-Authors: Brice Siroux, Aubery Wissocq, Catherine Beaucaire, Christelle Latrille, Cristina Petcut, Jordan Calvaire, Michel Tabarant, Marc F Benedetti, Pascal E Reiller
    Abstract:

    Abstract The applicatIon of a multi-Site Ion-exchange (MSIE) model to the predictIon of contaminant behaviour onto soils or sediments requires a coherent adsorptIon database. Following the same approach exposed in preceding works on smectite (Siroux et al., Appl. Geochem. 87, 167; Wissocq et al., Appl. Geochem., 93, 167), a database is here implemented to allow modelling the adsorptIon of radIonuclides 90Sr and 137Cs onto Na-illite, one of the major clay mineral encountered in the terrestrial environment. This database allows describing the adsorptIon properties of Sr2+ and Cs+ competing with major catIons H+ — considered as the reference catIon — and Na+ onto an Na-illite. To obtain the adsorptIon Site capacities and selectivity coefficients of illite Sites for Na+ towards H+, a saturatIon curve of Na+ on Na-conditIoned illite was acquired. AdsorptIon isotherms issued from literature have been reinterpreted using the MSIE model to obtain the adsorptIon properties of Sr2+ and Cs+ onto purified and Na-conditIoned illite. Afterwards, the predictability and robustness of the database were verified simulating experimental adsorptIon of Sr2+ and Cs+ onto Na-illite/Na-smectite mixtures.

  • applicatIon of the multi Site Ion exchanger model to the sorptIon of sr and cs on natural clayey sandstone
    Applied Geochemistry, 2017
    Co-Authors: Aubery Wissocq, Catherine Beaucaire, Christelle Latrille
    Abstract:

    Abstract To ensure the environmental monitoring of nuclear Sites, sorptIon models enabling the predictIon of contaminant migratIon (such as 90Sr and 137Cs) in soils, sediments and aquifers need to be developed. This paper aims 1) at developing a database containing the sorptIon properties of the pure mineral phases commonly encountered in natural environments and 2) at using this database in a multi-Site Ion exchange model to be applied on natural sediments. In additIon to some raw adsorptIon data issued from literature, different sorptIon experiments of Sr and Cs, on pure illite and smectite, in competitIon with calcium were carried out, as a functIon of pH and as well as concentratIons of Sr and Cs. These sorptIon data were interpreted using a multi-Site Ion-exchange model and contributed to the elaboratIon of a thermodynamic database gathering the retentIon properties of illite and smectite (Site capacities and selectivity coefficients) towards Cs+, Sr2+, H+ and Ca2+. A multi-Site Ion exchange model based on the mixture of pure mineral phases (illite and smectite) was successfully applied to simulate the Sr and Cs behavior in a natural clayey sandstone, indicating that the additivity of retentIon properties of the minerals constituting the sediment can be verified.

Anthony K Cheetham - One of the best experts on this subject based on the ideXlab platform.

  • am mn h2poo 3 a new family of hybrid perovskites based on the hypophosphite ligand
    Journal of the American Chemical Society, 2017
    Co-Authors: Sammy Shaker, Federico Brivio, Ramaswamy Murugavel, P D Bristowe, Anthony K Cheetham
    Abstract:

    A family of five hybrid ABX3 perovskites has been synthesized using hypophosphite (H2POO)- as the X-Site Ion. These compounds adopt the general formula [Am]Mn(H2POO)3, where Am = guanidinium (GUA), formamidinium (FA), imidazolium, triazolium, and dabconium. We explore the diverse structural and phase transitIon behavior of these materials through single-crystal diffractIon measurements and demonstrate contrasting magnetism in two of the phases, Am = GUA and FA, that arises from structural distortIons. The results show that hypophosphite perovskites offer a promising platform for generating new functIonal materials.

  • [Am]Mn(H2POO)3: A New Family of Hybrid Perovskites Based on the Hypophosphite Ligand
    2017
    Co-Authors: Sammy Shaker, Federico Brivio, Ramaswamy Murugavel, P D Bristowe, Anthony K Cheetham
    Abstract:

    A family of five hybrid ABX3 perovskites has been synthesized using hypophosphite (H2POO)− as the X-Site Ion. These compounds adopt the general formula [Am]­Mn­(H2POO)3, where Am = guanidinium (GUA), formamidinium (FA), imidazolium, triazolium, and dabconium. We explore the diverse structural and phase transitIon behavior of these materials through single-crystal diffractIon measurements and demonstrate contrasting magnetism in two of the phases, Am = GUA and FA, that arises from structural distortIons. The results show that hypophosphite perovskites offer a promising platform for generating new functIonal materials

O Chmaissem - One of the best experts on this subject based on the ideXlab platform.

  • relatIonship between structural parameters and the neel temperature in sr 1 x ca x mno 3 0 x 1 and sr 1 y ba y mno 3 y 0 2
    Physical Review B, 2001
    Co-Authors: O Chmaissem, B Dabrowski, S Kolesnik, J Mais, Dennis E Brown, R Kruk, P Prior
    Abstract:

    The crystal and magnetic structures of newly synthesized ${\mathrm{Sr}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ $(0l~xl~1)$ and ${\mathrm{Sr}}_{1\ensuremath{-}y}{\mathrm{Ba}}_{y}{\mathrm{MnO}}_{3}$ $(yl~0.2)$ perovskite materials (of the $\mathrm{AB}{\mathrm{O}}_{3}$ type) were investigated using neutron and synchrotron x-ray powder diffractIon at temperatures between 10 and 530 K. Upon decreasing the size of the A-Site Ion (or the unit-cell size) a series of structural transitIons appears at room temperature from cubic $\mathrm{Pm}3\ifmmode\bar\else\textasciimacron\fi{}m$ to tetragonal $I4/mcm$ (at $x\ensuremath{\sim}0.3)$ to orthorhombic Pbnm at $x\ensuremath{\sim}0.4.$ In agreement with neutron-diffractIon data, resistive and magnetic measurements show that the samples are antiferromagnetic with N\'eel temperatures ${T}_{N},$ varying from 233 to \ensuremath{\sim}125 K and from 233 to 212 K by increasing the Ca and Ba contents, respectively. The observed variatIon of ${T}_{N}$ cannot be solely explained by the changes of the unit-cell size or the average Mn-O-Mn bond angle \ensuremath{\theta}. The behavior of ${T}_{N}$ can be satisfactorily described as a functIon of $〈{\mathrm{cos}}^{2}\ensuremath{\theta}〉$ related to the superexchange interactIon integral, and ${\ensuremath{\sigma}}^{2},$ the A-Site Ionic size variance [L. M. Rodriguez-Martinez and J. P. Attfield, Phys. Rev. B 54, R15 622 (1996)] regardless of the structural symmetry of the perovskite material.