Untitled

High pressure effects on liquid viscosity and glass transition behaviour, polyamorphic phase transitions and structural properties of glasses and liquids

“…Such a positive ð@=@PÞ T relation is in keeping with the positive ð@T c =@PÞ T measured for polymers, and it is as expected from 'free volume' theories of liquid systems, including simple liquids and polymers [2,[5][6][7][8][9][10]. Generally, it is accepted that viscosity and T g should increase with pressure for a wide variety of liquids [8][9][10]. However, it has been noted that the Da term can become negative resulting in negative ð@T c =@PÞ T and (@g/@P) T relations for specific substances [11,12].…”

“…In another part of his work on pressure effects on viscosity (g) for a wide range of elemental, molecular and inorganic liquids, Bridgman found that ð@=@PÞ T had a positive slope [1]. Such a positive ð@=@PÞ T relation is in keeping with the positive ð@T c =@PÞ T measured for polymers, and it is as expected from 'free volume' theories of liquid systems, including simple liquids and polymers [2,[5][6][7][8][9][10]. Generally, it is accepted that viscosity and T g should increase with pressure for a wide variety of liquids [8][9][10].…”

“…The viscosity of liquid H 2 O as a function of P and T within the stable and supercooled liquid regimes has been determined [1,12]. At T > T m , ð@=@PÞ T has a positive Excluding the 'anomalous' behavior of liquid H 2 O, the outcome of various experimental and theoretical studies of a wide range of liquid and glassy systems has been that positive ð@=@PÞ T and ðÁT c = Á PÞ T relations were to be expected from simple models of liquid structure and relaxation [8][9][10]. However, that situation was changed abruptly following a series of measurements for silicate and aluminosilicate liquids, that form the largest class of glass-forming materials, and that are important to the geochemical community [11,12,17].…”

High index-contrast all-solid photonic crystal fibers by pressure-assisted melt infiltration of silica matrices

“…Even in mildly confined conditions, inorganic melts may exhibit several peculiarities. These include positive [5] or negative [6,7] dependence of viscosity on pressure, pressure-induced structural changes [8], the evolution of anisotropic flow and structural rearrangement [9,10], crystallization [11,12] and solubility of gases [13,14]. Compared to organic fluids (and particularly polymer melts), for reasons of experimental limitations, these phenomena are typically difficult to assess.…”

Effect of high pressure in the Li2O–2SiO2 crystallization

“…Gutzow et al [13] presented a thorough study of the kinetics of melt crystallization under applied static pressures, taking into account the thermodynamic and kinetic consequences of pressure on nucleation and crystal growth rates. They pointed out that only at very high loads (in the GPa region) can static pressure exert a real catalytic effect in the crystallization of glasses.…”