Interfacial Melting of Ice in Contact with ${\mathrm{SiO}}_2$

The physical behavior of condensed matter can be drastically altered in the presence of interfaces. Using a high-energy x-ray transmission-reflection scheme, we have studied ice-${\mathrm{SiO}}_2$ model interfaces. We observed the formation of a quasiliquid layer below the bulk melting temperature and determined its thickness and density as a function of temperature. The quasiliquid layer has stronger correlations than water and a large density close to ${\rho }_{\mathrm{HDA}}=1.17\mathrm{g}/{\mathrm{cm}}^3$ of high-density amorphous ice suggesting a structural relationship with the postulated high-density liquid phase of water.

Figure 1

Scenario for interface melting of ice at an inhomogeneous interface upon approaching the melting point $T_m$.

Figure 2

Sketch of the experimental setup (see the text).

Figure 3

(a) Reflectivity curves of the ice-${\mathrm{SiO}}_2$ interface in the vicinity of the ice melting point. Solid lines are fits to the data using the (dynamical) Parratt formalism [18]. (b) $\rho (z)$ across the interface well below the onset temperature for interfacial melting ($T=T_m-25\mathrm{K}$) and close to the melting point ($T=T_m-0.036\mathrm{K}$). (c) Real space model of the ice-${\mathrm{SiO}}_2$ interface associated with $T=T_m-1\mathrm{K}$. The densities used in this representation correspond to the values deduced from the measurement.

Figure 4

(a) Temperature dependence of the thickness $L$ of the quasiliquid layer. The straight line is a fit to a logarithmic growth law. (b) Temperature dependence of the average density ${\rho }_{\mathrm{qll}}$ in the quasiliquid layer. The fitted (straight) line indicates the trend for a decreasing average density with growing layer thickness.

Figure 5

Phase diagram of water at moderate pressures compiled from Refs. 1, 22. The dashed blue lines terminating in a tentative critical point C separate low density and high density water from low density and high density amorphous ice. The numbers in parentheses denote the densities (at atmospheric pressure).