Étude des propriétés physicochimiques de verres borosilicatés et de borosilicates de lanthane par dynamique moléculaire à partir d’un champ de force polarisable

Abstract : As result of the nuclear waste vitrification, the knowledge and understanding of the dynamic and structural properties of glasses, including the behavior of radionuclides, is important (in liquid and solid phases). It can influence the glass waste properties, the lifetime of the vitrification process and the amount of radionuclides introduced in the glass matrix. Molecular dynamic simulations have been done to study the influence of the glass matrix composition into the structural and dynamic properties of the glass. A simplified glass, with 3 major oxides of the R7T7 glass such as SiO2, B2O3 and Na2O, have been used to simulate the R7T7 industrial nuclear glass (a 30 oxides glass). The inclusion of La2O3 allows us to simulate the impact of fission products and minor actinides into the properties of the glass matrix. Both systems, the SiO2-B2O3-Na2O and SiO2-B2O3-Na2O-La2O3, allow us to study the sodium and lanthanum effect on the properties of the glass. During this work, a polarizable force field has been developed to do these simulations. The results obtained at room temperature let us reproduce the experimental results of the structure, the distribution of BIII/BIV and the density. A study has been done on the viscosity and electrical conductivity of the liquid. The distribution BIV/BIII and the influence of the structural changes on the density along with the temperature have also been observed with thermal quenchings. The current limits of this approach are also described.
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Fabien Pacaud. Étude des propriétés physicochimiques de verres borosilicatés et de borosilicates de lanthane par dynamique moléculaire à partir d’un champ de force polarisable. Chimie théorique et/ou physique. Université Pierre et Marie Curie - Paris VI, 2016. Français. ⟨NNT : 2016PA066504⟩. ⟨tel-01525820⟩

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