Collective Behavior of Supercooled Liquids in Porous Media

NMR Study of Phase Transitions in Pure Water and Binary H2O/HNO3Films Adsorbed on Surface of Pyrogenic Silica

“…It has been shown that the relative to bulk state ( 9,10 ) . Properties of water in capiladsorbed water in the porous medium freezes at a tempera-laries and thin films were found to be remarkably different ture below the normal freezing point of bulk water.…”

Characterization of zinc implanted silica: Effects of thermal annealing and picosecond laser radiation

“…[1][2][3][4][5][6][7] For example, ͑1͒ the physical confinement, the interfacial interaction between guest and host, and the reduction of the physical size of the confined particles can lead to ͑a͒ hardness change of materials; 1 ͑b͒ depression of the melting and freezing phase transition temperatures; 2 and ͑c͒ alteration of crystal nucleation and growth characteristics; 3 ͑2͒ the quantum confinement of free electrons in metals and excitons in semiconductors can result in the observation of the surface plasmon resonance ͑SPR͒ and the shifts of the band gap, respectively; 4,5 ͑3͒ dielectric confinement gives rise to surface phonon observation in a wide range of nanophase materials. [1][2][3][4][5][6][7] For example, ͑1͒ the physical confinement, the interfacial interaction between guest and host, and the reduction of the physical size of the confined particles can lead to ͑a͒ hardness change of materials; 1 ͑b͒ depression of the melting and freezing phase transition temperatures; 2 and ͑c͒ alteration of crystal nucleation and growth characteristics; 3 ͑2͒ the quantum confinement of free electrons in metals and excitons in semiconductors can result in the observation of the surface plasmon resonance ͑SPR͒ and the shifts of the band gap, respectively; 4,5 ͑3͒ dielectric confinement gives rise to surface phonon observation in a wide range of nanophase materials.…”

The Structure of Confined Oxygen in Silica Xerogels

“…The S(Q) profile changes little in this temperature range, indicating that the structure of the liquid in the pores, even in the supercooled regime, is quite ordinary. Dynamical experiments (6), in contrast, have revealed quite different behavior for the supercooled liquid. The liquid-solid transition of the oxygen in the pores is marked by the appearance of diffraction peaks, which are a clear indication of long-range translational correlations and solidification.…”

“…Previous studies of freezing in porous media have shown significant deviations from bulk freezing (2)(3)(4)(5), such as a depression of the freezing temperature and a large hysteresis between cooling and warming. The dynamical properties of the supercooled liquid are also different from those of conventional bulk liquids (2,6). Recent comDuter simulations of freezing in con-fined geometries (7,8 ) have resulted in enhanced, rather than suppressed, freezing temperatures.…”