title: High-energy X-ray diffraction from aluminosilicate liquids.
abstract: Containerless high energy X-ray diffraction measurements have been performed on molten Al(2)O(3)-SiO(2) as a function of composition. The data show a strong distortion of the SiO(4) tetrahedral units and a breakdown of intermediate range order as alumina is added. For silica-rich compositions, the X-ray pair distribution functions are consistent with the presence of 4-fold oxygen triclusters predicted by molecular dynamics simulations, where these liquids exhibit relatively high viscosities compared to other binary silicates. For higher alumina content liquids, the average cation-oxygen coordination number gradually increases with increasing Al(2)O(3) content, but the pair distribution functions change very little with composition, suggesting the increased presence of disordered AlO(n) (n = 4,5,6) polyhedra are associated with low viscosity melts. A comparison of the liquid and glassy X-ray pair distributions functions at the alumina-rich mullite composition indicate a significant distortion of the polyhedra in the melt, suggesting structural changes are temperature dependent.
authors.affiliation: Institute of Mathematical and Physical Sciences, Aberystwyth University, Aberystwyth, Ceredigion SY23 3BZ, UK.
authors.forename: M C
authors.initials: MC
authors.lastname: Wilding
authors.forename: C J
authors.initials: CJ
authors.lastname: Benmore
authors.forename: J K R
authors.initials: JK
authors.lastname: Weber