Exploration of the phase diagram of liquid water in the low-temperature metastable region using synthetic fluid inclusions

Abstract

We present new experimental data of the low-temperature metastable region of liquid water derived from high-density synthetic fluid inclusions (996-916 kg m) in quartz. Microthermometric measurements include: (i) prograde (upon heating) and retrograde (upon cooling) liquid-vapour homogenisation. We used single ultrashort laser pulses to stimulate vapour bubble nucleation in initially monophase liquid inclusions. Water densities were calculated based on prograde homogenisation temperatures using the IAPWS-95 formulation. We found retrograde liquid-vapour homogenisation temperatures in excellent agreement with IAPWS-95. (ii) Retrograde ice nucleation. Raman spectroscopy was used to determine the nucleation of ice in the absence of the vapour bubble. Our ice nucleation data in the doubly metastable region are inconsistent with the low-temperature trend of the spinodal predicted by IAPWS-95, as liquid water with a density of 921 kg m remains in a homogeneous state during cooling down to a temperature of -30.5 °C, where it is transformed into ice whose density corresponds to zero pressure. (iii) Ice melting. Ice melting temperatures of up to 6.8 °C were measured in the absence of the vapour bubble, i.e. in the negative pressure region. (iv) Spontaneous retrograde and, for the first time, prograde vapour bubble nucleation. Prograde bubble nucleation occurred upon heating at temperatures above ice melting. The occurrence of prograde and retrograde vapour bubble nucleation in the same inclusions indicates a maximum of the bubble nucleation curve in the ϱ-T plane at around 40 °C. The new experimental data represent valuable benchmarks to evaluate and further improve theoretical models describing the p-V-T properties of metastable water in the low-temperature region.

Regeneration of capillary water in unsaturated zones

“…The same stretched superheated state of water can be found in closed micrometric cavities like fluid inclusions or Berthelot tubes. The difference is that in this case, water is brought into the superheated state not by capillary forces at constant temperature but by heating and isochoric cooling (e.g., Roedder, 1967;Alvarenga et al, 1993;Caupin and Herbert, 2006;Shmulovich et al, 2009;Qiu et al, 2016).…”

Metastable phase equilibria in the ice II stability field. A Raman study of synthetic high-density water inclusions in quartz

“…In previous experimental studies synthetic fluid inclusions have successfully been used to explore the metastable super-heated domain of liquid water reaching negative pressures of up to -140 MPa. [11][12][13][14][15] The present study uses this experimental approach to explore metastable phase equilibria at temperatures below ice nucleation. Recently, an extensive experimental study has been published by Qiu et al 15 exploring the low-temperature metastable region of liquid water using synthetic fluid inclusions in quartz.…”

“…[11][12][13][14][15] The present study uses this experimental approach to explore metastable phase equilibria at temperatures below ice nucleation. Recently, an extensive experimental study has been published by Qiu et al 15 exploring the low-temperature metastable region of liquid water using synthetic fluid inclusions in quartz. By means of classical fluid inclusion microthermometry they measured temperatures (T) of a series of different phase transitions as a function of density (ϱ) in the temperature range between 150 and -43 °C determining the ϱ-T trends of 1. the ice nucleation curve at negative pressures, 2. the ice Ih melting curve at negative pressures, 3. the super-cooled saturation curve, and 4. the line of spontaneous vapour bubble nucleation (cavitation) at high negative pressures.…”

Compressibility Anomalies in Stretched Water and Their Interplay with Density Anomalies

“…One would need to obtain data at more negative pressure, but this is not possible with our technique: our lowest density FI has reached the homogeneous cavitation line measured in Ref. (14).…”

“…Six FIs synthesized hydrothermally (14) were selected to cover evenly the density range between liquid-vapor equilibrium down to the cavitation limit, at which vapor nucleation occurs spontaneously. Sound velocity was measured from −13.9 to 151…”