Percolation channels: a universal idea to describe the atomic structure and dynamics of glasses and melts

Reference	Presenter	Authors (Institution)	Abstract
10-068	Daniel R. Neuville	Neuville, D.R.(CNRS-IPGP); Le Losq, C.(ANU- Canberra); Chen, W.(State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan); Florian, P.(CNRS-CEMHTI Orléans); Massiot, D.(CNRS-CEMHTI Orléans); Zhou, Z.(Department of Mathematics and Physics, Aberystwyth University, Physical Sciences Building, Aberystwyth); Greaves, N.(Department of Mathematics and Physics, Aberystwyth University, Physical Sciences Building, Aberystwyth, Ceredigion, SY23 3BZ, UK University of Cambridge, Department of Materials Science & Metallurgy, Cambridge CB3 0FS, UK. State Key Laboratory of Silicat);	Understanding the links between chemical composition, nano-structure and the dynamic properties of silicate melts and glasses is fundamental to both Earth and Materials Sciences. Central to this, is whether the distribution of mobile metallic ions is random or not. In silicate systems, such as window glass, it is well-established that the short-range structure is not random but metal ions cluster to form percolation channels through a partly broken network of corner-sharing SiO4 tetrahedra. In alumino-silicate glasses and melts, extensively used in industry and representing most of the Earth magmas, metal ions compensate the electrical charge deficit of AlO4- tetrahedral, but until now clustering has not been confirmed. Here we report how major changes in melt viscosity, together with glass Raman and Nuclear Magnetic Resonance measurements and Molecular Dynamics simulations, all demonstrate metal ions nano-segregating into channels, making this a universal phenomenon of oxide glasses and melts. Furthermore, we can explain how, in both single and mixed alkali compositions, metal ion clustering and percolation radically affect melt mobility, central to understanding industrial and geological processes.
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