Results are presented from theoretical and experimental infrared (IR) spectroscopy studies of the microstructures of poly(silsesquioxane)s (PSSQs) of varying chemical composition. The calculated IR spectra show two distinct asymmetric Si-O-Si stretch vibration bands for models of complete polyhedral cages, incomplete open cages, and short ladder structures. Close analyses of the calculated results indicate that the higher frequency IR band at about 1150 cm -1 is derived from the parallel asymmetric Si-O-Si stretch vibration mode in the (Si-O) n ring subunit while the lower frequency band at about 1050 cm -1 is due to the asymmetric Si-O-Si stretch symmetric with respect to the inversion point at the center of the (Si-O) n ring and is absent in highly symmetric cage structures. Experimentally, poly(methylsilsesquioxane) (PMSQ), poly(isobutylsilsesquioxane) (PiBSQ), and poly(phenylsilsesquioxane) (PPhSQ) exhibit a varying tendency of cage-like structures, rather than ladder structures, in as-polymerized samples. When the thermal conversion (curing) temperature is increased to 400 °C, the microstructure of PMSQ in thin solid films transforms from open cage-like structure toward a random network with lower symmetry. This change in microstructure is caused by the secondary condensation reaction and the evaporation of cage structures, and the effect of cage evaporation becomes most pronounced for PiBSQ films, which are mostly comprised of cage-like structures that evaporate around 280 °C. In comparison, PPhSQ films retain cage-like structure upon curing to 400 °C as a result of the high evaporation temperature (ca. 500 °C) of the cages.

We present the results of a structural study of metallic alloy liquids from high temperature through the glass transition. We use high energy X-ray scattering and electro-static levitation in combination with molecular dynamics simulation and show that the height of the first peak of the structure function, S(Q) − 1, follows the Curie-Weiss law. The structural coherence length is proportional to the height of the first peak, and we suggest that its increase with cooling may be related to the rapid increase in viscosity. The Curie temperature is negative, implying an analogy with spin-glass. The Curie-Weiss behavior provides a pathway to an ideal glass state, a state with long-range correlation without lattice periodicity, which is characterized by highly diverse local structures, reminiscent of spin-glass.

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Zr-based metallic glasses are prepared by quenching supercooled liquid under pressure. These glasses are stable in ambient conditions after decompression. The High Pressure Quenched glasses have a distinct structure and properties. The pair distribution function shows redistribution of the Zr-Zr interatomic distances and their shift towards smaller values. These glasses exhibit higher density, hardness, elastic modulus, and yield stress. Upon heating at ambient pressure, they show volume expansion and distinct relaxation behavior, reaching an equilibrated state above the glass transition. These experimental results are consistent with an idea of pressure-induced low to high density liquid transition in the supercooled melt.

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