The atomic-scale structure of germanium diselenide (GeSe(2)) glass has been revisited using a combination of high-energy x-ray diffraction and constrained reverse Monte Carlo simulations. The study shows that the glass structure may be very well described in terms of a continuous network of corner- and edge-sharing Ge-Se(4) tetrahedra. The result is in contrast to other recent studies asserting that the chemical order and, hence, network integrity in GeSe(2) glass are intrinsically broken. It is suggested that more elaborate studies are necessary to resolve the controversy.

Small-angle X-ray scattering is used at two energies, one either side of the zirconium K-edge, to probe the in situ formation of an alumina-zirconia-silicate ceramic. The use of energies either side of the edge allows the decomposition of information regarding the scattering from the zirconia particles from that of the glass matrix. Porod slope data show how the nanoparticles progress from being relatively isolated particles to becoming agglomerates as the pore network in the glass collapses. The shape of the agglomerates resembles the pore network of the glass at low temperature. The Guinier radii of the particles show the growth of the agglomerates past the Littleton softening point, whilst still resolving the primary particles.

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An alumina -zirconia nanocomposite has been produced using the chloride sol -gel method and embedded into a silicate matrix by dispersing the nanocomposite into a powdered silica glass and subsequent annealing. The resultant nanoceramic was subjected to 27 Al magic angle spinning (MAS) NMR, small angle X-ray scattering (SAXS), and X-ray photoelectron spectroscopy (XPS), leading to a core-shell type model of the interfacial region. Initially the particles are agglomerated with the shell containing mainly atoms of octahedral coordination and the core aluminium atoms of tetrahedral coordination. Upon annealing the agglomerates break up, causing a change in the coordination of the aluminium atoms. As the atoms diffuse into the matrix, the ones that were initially in the shell change to be tetrahedrally coordinated, and therefore increase the overall population of tetrahedrally coordinated aluminium atoms within the interface.MST/6105

Energy-dependent small-angle x-ray scattering (SAXS) measurements near the Zr-K absorption edge of a nano-scale alumina-zirconia-silicate ceramic are reported.The in-situ experiments cover the temperature range from 250 • C to 725 • C, during which the sol-gel prepared nano-particles consolidate and the glass matrix phase begins to soften, leading to a compaction of the ceramic. The dominant scattering mechanism changes from a surface-fractal type to a mass-fractal type linked to direct contact areas between nano-particles and matrix. The energy-dependent data identify the zirconium-bearing phase as dominant in the high-q range. The experimental data are placed in the context of recent advances in in-situ anomalous small-angle x-ray scattering (ASAXS) and some experimental problems and solutions of near-edge scattering are discussed.

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