Читать книгу Encyclopedia of Glass Science, Technology, History, and Culture - Группа авторов - Страница 232

Technical advances continue to increase the quality, depth, and breadth of information that can be obtained about short‐range structure and order in oxide glasses, for example, microscale XAS, X‐ray Raman, improved neutron scattering facilities, and NMR at higher magnetic fields and with methods that allow better measurements of internuclear distances and connectivities. Combination of experimental data from different methods, to yield consistent models, is especially powerful, as illustrated in Figure 7 [18]. Some of these approaches are now feasible for in‐situ studies of high‐temperature liquids and even of liquids at high pressure and temperature. Advances in theory are beginning to allow accurate forward calculation of spectra (e.g. vibrational and NMR) from structural models [19]. This information can then be combined with experimental data to obtain much more complete views of structure, quantitative extent of disorder, and their links to thermodynamic properties that depend critically on configurational entropy, such as viscosity, heat capacity, and the bulk free energy. As researchers move beyond model‐dependent fitting and interpretation of spectra of glasses to more complete theoretical analyses, our understanding of the true complexities of these fascinating and useful materials will expand enormously.

Figure 7 Partial pair distribution functions g_ij(r) calculated from a “reverse Monte Carlo” model combining X‐ray and neutron diffraction data for various CaSiO₃–MgSiO₃ glasses.

Source: Reprinted with permission from [18].