Speaker
Prof.
Thomas Loerting
(University of Innsbruck)
Description
Liquid water crystallizes rapidly both below the homogeneous
nucleation line T_H and above the crystallization line T_X.
The "no-man's land" inbetween T_H and T_X, in which liquid
water can only be studied on ultrashort timescales,
represents a region, in which the properties of water are
largely unknown. It has, thus, been a playground for
computer simulations on the nanosecond timescale, which
predict contradictory scenarios about water's properties. In
our work we have studied the properties of amorphous ices
and deeply supercooled water in the vicinity of T_X. By
applying different protocols for the preparation of amorphous
ices we were able to push the T_X boundary to 5-10 K higher
temperatures in the pressure range up to 500 MPa, therebye
narrowing the no-man's land and providing access to bulk
water's properties in a broader temperature range. Within
this temperature range the amorphous ices soften
significantly and relaxation times reach the subsecond
domain so that they can be regarded as ultraviscous liquids.
Analysis of crystallization kinetics suggests that the
elimination of nano-crystalline domains in both low- (LDA)
and high-density amorphous ices (HDA) is the key to the shift
of the T_X line. In the absence of nano-crystalline domains
within the glassy matrix crystallization is delayed because
one channel leading to crystal growth is essentially
suppressed.
Co-authors
Josef Stern
(University of Innsbruck)
Katrin Amann-Winkel
(University of Innsbruck)
Markus Seidl
(University of Innsbruck)
Philip Handle
(University of Innsbruck)
Stephan Fuhrmann
(University of Innsbruck)
