Relaxation dynamics and transformation kinetics of deeply supercooled water: Temperature, pressure, doping, and proton/deuteron isotope effects

Abstract

Above its glass transition, the equilibrated high-density amorphous ice (HDA) transforms to the low-density pendant (LDA). The temperature dependence of the transformation is monitored at ambient pressure using dielectric spectroscopy and at elevated pressures using dilatometry. It is found that near the glass transition temperature of deuterated samples, the transformation kinetics is 300 times slower than the structural relaxation, while for protonated samples, the time scale separation is at least 30 000 and insensitive to doping. The kinetics of the HDA to LDA transformation lacks a proton/deuteron isotope effect, revealing that this process is dominated by the restructuring of the oxygen network. The x-ray diffraction experiments performed on samples at intermediate transition stages reflect a linear combination of the LDA and HDA patterns implying a macroscopic phase separation, instead of a local intermixing of the two amorphous states.

Nature of Water’s Second Glass Transition Elucidated by Doping and Isotope Substitution Experiments

“…One recognizes that the effective activation energies for all of the differently doped eHDA ices are close to each other; the same holds for the LDA samples. In particular, while substitution of hydrogens by deuterons slows the dynamics significantly [46,47], Fig. 6(b) confirms the absence of any doping-induced dynamical enhancement in eHDA as well as in LDA.…”

“…6(b) we compare them with those for undoped [14] and HCl-doped (hydrogenated) samples. Data for deuterated amorphous ices are included as well [46,47]. One recognizes that the effective activation energies for all of the differently doped eHDA ices are close to each other; the same holds for the LDA samples.…”

Deeply supercooled aqueous LiCl solution studied by frequency-resolved shear rheology

“…40 Previous dielectric studies concerned with the dynamics of HGW or ASW were either conducted as a function of temperature at a few frequencies, [9][10][11]41 or the samples were studied after pore collapse (with information on impurities trapped from the background gas between resulting lamellae or in remaining micropores not available). 42,43 Effects of doping on the dynamics of amorphous 16,[44][45][46] and crystalline [47][48][49] ices were also intensively examined. From dielectric as well as from calorimetric work, it has become clear that the implantation of defects into the H 2 O network can make a distinctive difference.…”

“…48,49 Conversely, for the numerous dopants tested so far, such enhancements appear to be absent in the amorphous ices. 16,[44][45][46] In order to explore the extent to which various undoped ice forms can be distinguished on the basis of dynamical properties, here we report on broadband dielectric spectra for HGW and compare them with dielectric results obtained for the amorphous ices ASW, 11,42,43 LDA, and HDA. 53 Further comparison is made with dielectric data reported for various crystalline ices, again, without intentional impurity doping.…”

Supercooled and glassy water: Metastable liquid(s), amorphous solid(s), and a no-man’s land

“…One important precondition for the existence of two distinct liquids is that their relaxation times need to be clearly shorter than their transformation times. It was shown very recently that indeed the dielectric relaxation times in HDA are about three orders of magnitude shorter than the polyamorphic transformation, and similarly the relaxation times in LDA are about three orders of magnitude shorter than crystallization times (109). The observation of a calorimetric glass transition temperature for HDA (the so-called second glass transition) clearly distinct from the one of LDA has been interpreted as evidence that water has two distinct phases above its glass transition temperatures (101).…”