Boron-speciation and aluminosilicate crystallization in alkali boroaluminosilicate glasses along the NaAl1-xBxSiO4 and LiAl1-xBxSiO4 joins

Abstract The influences of boron on silicate glass dissolution behavior and crystallization have long been important in the nuclear waste glass and technical glass communities. Boron is a challenging component to model due to this ability to assume three- and four-fold coordinations with oxygen, as well as its ability to form complex structural units with silicate tetrahedra. Furthermore, the low atomic mass limits the available characterization techniques. In the present work, recent literature findings on the compositional influence on boron speciation are implemented to interpret new data on alkali boroaluminosilicate glasses studied with 11B nuclear magnetic resonance (NMR), synchrotron X-ray scattering (s-XRS), and chemical durability measurements. The purpose of this study is to understand the influence of boron on the crystallization behavior of sodium and lithium aluminosilicate systems, NaAl1-xBxSiO4 and LiAl1-xBxSiO4, as applied to problems in nuclear waste vitrification. Comparisons are drawn between the alkali coordination number and crystallization behavior as a function of boron addition, as obtained through modeling of synchrotron X-ray total scattering using Empirical Potential Structural Refinement.