Inorganic glasses, glass-forming liquids and amorphizing solids

Abstract

Greaves, George; Sen, S., (2007) 'Inorganic glasses, glass-forming liquids and amorphizing solids', Advances in Physics 56(1) pp.1-166 RAE2008We take familiar inorganic oxide glasses and non-oxide glasses and the liquids from which they derive to review the current understanding of their atomic structure, ranging from the local environments of individual atoms to the long-range order which can cover many interatomic distances. The structural characteristics of important glasses and melts, like silicates, borates, alumino-silicates, halides and chalcogenides, are drawn from the results of recent spectroscopy and scattering experiments. The techniques include Nuclear Magnetic Resonance (NMR) and X-ray Absorption Fine Structure (XAFS), Neutron Scattering (NS) and Small- and Wide-angle X-ray Scattering measurements (SAXS/WAXS), and are often combined with computer simulation experiments in order to obtain detailed images of structure and diffusion in the glassy as well as in the molten state. We then review the current understanding of relaxation in glasses, liquids and polyamorphic states. This includes phenomenological models and theories of relaxation in different dynamical regimes, spectroscopic studies of atomic-scale mechanisms of viscous flow in inorganic glass-formers and the signatures of relaxational behaviour embedded in the low-frequency vibrational dynamics of glasses including the Boson peak and the Two-Level Systems (TLS) that control conformational transformation. We conclude this review by extending concepts of the dynamics of the glass transition from the supercooled liquid in order to understand the solid-state amorphization of crystals under temperature and pressure and to determine the thermodynamic limits of the crystalline and glassy state.Peer reviewe

Universal relation between viscous flow and fast dynamics in glass-forming materials

“…This observation provides a way to extend the fragility concept to the glassy state and, in principle, indicates how to determine the fragility uniquely from glass properties well below T g . It was soon realized, however, that the NEF determined in a similar way in some complex systems does not obey the proposed linear correlation, 18,22,23 a result recently discussed in the light of isobaric vs isochoric definition of fragility. 24 In this work, we demonstrate how this apparent failure is hidden in the break down of the validity of Eq.…”

“…Among them, ͑i͒ the thermodynamic approach to the fragility 4,5 also in the light of the Adam-Gibbs ͑AG͒ theory [6][7][8] and the random first-order transition; 9 ͑ii͒ the ratio between the maximum and the minimum of the boson peak, i.e., of the bump observed at the Thz frequencies in the Raman-and neutron-scattering spectra of glass-forming materials; 10 ͑iii͒ the degree of stretching in the nonexponential decay of the correlation functions in the liquid close to T g ͑Ref. 11͒; ͑iv͒ the statistics of the minima in a potential energy landscape-based description of the diffusion process in supercooled liquids; 12,13 ͑v͒ the temperature behavior of the high frequency shear elastic modulus in the supercooled liquid; 14 ͑vi͒ the Poisson ratio; [15][16][17][18] ͑vii͒ the mean squared displacement in a glass, which for different systems seems to stand in the same order as they stand in a T g scaled Arrhenius plot. 19,20 In all these studies, the fragility has been always related to macroscopic properties on approaching the glass transition from the liquid side.…”

Persistent homology and many-body atomic structure for medium-range order in the glass

“…However, it becomes clear that the larger-scale structures beyond neighbor atoms so-called medium-range order (MRO) are much more important than SRO in glasses. The amorphous structures are essentially characterized by possible connection of SRO that can build up continuous atomic configurations throughout the materials without any periodicity [1,2,3,4,5,6,7,8].…”

The formation of glass: a quantitative perspective

“…According to earlier studies, glass can be characterized using a series of plots of thermodynamic properties (energy, volume, enthalpy, or entropy) as a function of temperature [15,32,74]. In general, the behavior of the thermodynamic parameters of supercooled melts from the melting temperature T m to the glass transition temperature T g can only be predicted by extrapolating high-temperature data to the low-temperature region because of the strong tendency of such melts to crystallize [75].…”