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Exploration of the phase diagram of liquid water in the metastable region by means of synthetic fluid inclusions

English title Exploration of the phase diagram of liquid water in the metastable region by means of synthetic fluid inclusions
Applicant Frenz Martin
Number 140777
Funding scheme Project funding (Div. I-III)
Research institution Institut für angewandte Physik Universität Bern
Institution of higher education University of Berne - BE
Main discipline Condensed Matter Physics
Start/End 01.03.2013 - 31.03.2015
Approved amount 160'783.00
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All Disciplines (2)

Discipline
Condensed Matter Physics
Other disciplines of Physics

Keywords (7)

metastable water; fluid inclusions; Brillouin scattering; microthermometry; femtosecond laser; phase nucleation; Raman scattering

Lay Summary (German)

Lead
Ziel unserer Forschungsarbeiten ist es die anomalen thermodynamischen Eigenschaften von Wasser anhand von Messungen an synthetisch hergestellten Flüssigeinschlüssen in Quarz zu verstehen. Die Untersuchungen sollen mit Hilfe von Raman und Brillouin Spektroskopie erfolgen. Die Ergebnisse werden uns helfen, die Eigenschaften von Wasser im metastabilen Bereich bei tiefen Temperaturen besser zu verstehen und den tatsächlichen Verlauf der Spinodale zu bestimmen.
Lay summary

Um die anomalen thermodynamischen Eigenschaften von Wasser, wie z.b. das Dichtemaximum bei 4oC oder das Minimum der isothermischen Kompressibilität bei 46oC zu verstehen, muss man mehr über den Bereich von metastabilem Wasser bei niedrigen Temperaturen erfahren. Der metastabile Bereich von Wasser erstreckt sich über einen weiten Bereich des Druck-Temperatur Diagramms und liegt zwischen der flüssig-gasförmigen Gleichgewichtskurve und der Spinodale von Wasser. Der Verlauf der Spinodale, die am kritischen Punkt von Wasser bei 374oC und einem Druck von 221 bar beginnt, hin zu tiefen Temperaturen ist nach wie vor unklar. Unterschiedliche theoretische Modelle sagen einen unterschiedlichen Verlauf voraus. Um diesen Bereich des Phasendiagrammes von Wasser experimentell untersuchen zu können, wollen wir synthetisch hergestellte mikroskopisch kleine Flüssigeinschlüsse in Quarz verwenden. Zur Untersuchung dieser Flüssigeinschlüsse verwenden wir optische Spektroskopie und messen die Raman und Brillouin Streuung. Die Ergebnisse sollen Aufschluss über den Verlauf der Spinodale von Wasser bei tiefen Temperaturen geben.

Direct link to Lay Summary Last update: 15.02.2013

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Exploration of the phase diagram of liquid water in the low-temperature metastable region using synthetic fluid inclusions
Qiu Chen, Krüger Yves, Wilke Matthias, Marti Dominik, Ricka Jaroslav, Frenz Martin (2016), Exploration of the phase diagram of liquid water in the low-temperature metastable region using synthetic fluid inclusions, in Physical Chemistry Chemical Physics, 18(10), 28227-28241.
Microthermometric data of stretched and super-cooled liquid water obtained from high-density synthetic fluid inclusions
Qiu Chen, Krüger Yves, Wilke Max, Marti Dominik, Rička Jaro, Frenz Martin (2015), Microthermometric data of stretched and super-cooled liquid water obtained from high-density synthetic fluid inclusions, in The Sorby Conference on Fluid and Melt Inclusions, ECROFI XXIII, 13, 103-104.

Collaboration

Group / person Country
Types of collaboration
Institut Lumiere Matiere France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Exchange of personnel
Dr. A. Murk, Microwave department, Institute of Applied Physics,University Bern Switzerland (Europe)
- Research Infrastructure
- Exchange of personnel
Dr. John Mavrogenes from the Australian National University, Canberra Australia (Oceania)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Dr. Max Wilke, Deutschen GeoForschungsZentrum, Potsdam Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Seminarvortrag Individual talk Liquid water in no man’s land–phase transition of water under negative pressure 23.05.2016 Villeurbanne, France Ricka Jaroslav; Qiu Chen; Krüger Yves; Frenz Martin;
ECROFI-XXIII Talk given at a conference Microthermometric data of stretched and super-cooled liquid water obtained from high-density synthetic fluid inclusions 29.06.2015 Leeds, Great Britain and Northern Ireland Ricka Jaroslav; Qiu Chen; Frenz Martin; Krüger Yves;
Seminar at the Department of Chemistry and Physics of Earth Materials Individual talk Exploration of the phase diagram of liquid water in the metastable region using synthetic fluid inclusions: A project description 14.01.2014 Potsdam, Germany Frenz Martin; Krüger Yves; Qiu Chen; Ricka Jaroslav;
S4-Summer School on Speleothem Science Talk given at a conference Fluid inclusion II: Liquid–vapour homogenisation 31.07.2013 Heidelberg, Germany Krüger Yves;


Associated projects

Number Title Start Funding scheme
119966 Determination of paleotemperatures from fluid inclusion liquid-vapour homogenization in speleothems 01.04.2008 Project funding (Div. I-III)
159542 Exploration of the phase diagram of liquid water in the metastable region by means of synthetic fluid inclusions 01.04.2015 Project funding (Div. I-III)
134861 Determination of paleo-temperatures using fluid inclusion liquid-vapour homogenization in speleothems: Correction of the measured temperature data 01.04.2011 Project funding (Div. I-III)

Abstract

The low temperature metastable region of liquid water is of particular importance to elucidate the anomalous thermodynamic properties of water, for example, the density maximum at 4°C and the minimum in the isothermal compressibility at 46°C. The metastable state of liquid water spans a wide range of p-T conditions between the liquid-vapour equilibrium curve and the liquid spinodal, i.e., the stability limit of the metastable liquid state. The spinodal curve starts at the critical point and runs to negative pressures (tensile stress) with decreasing temperature. At low temperatures, however, the shape of the spinodal curve is controversial and different theoretical models have been discussed in the literature. One of them is the “Stability Limit Conjecture” proposed by Speedy (1982), a thermodynamic model that postulates a single continuous stability limit (spinodal) for both, the superheated and the super cooled states of liquid water. The model assumes that the TMD line (Temperature of Maximum Density) remains negatively sloped in the metastable region and intersects the spinodal. As a thermodynamic consequence of this, the spinodal must pass through a pressure minimum at the intersection with the TMD line and returns to positive pressures at low temperatures. In contrast to the thermodynamic model proposed by Speedy, molecular dynamics simulations by Pool et al. (1992) indicate that the TMD line bends to a positive slope in the metastable region and does not intersect the spinodal curve. Consequently, the spinodal remains positively sloped at low temperatures and does not bend towards positive pressures. To shed light on this controversial issue, we propose an experimental approach using synthetic pure water inclusions to define the trend of the TMD line and the shape of the spinodal curve. Fluid inclusions are water filled microscopic sized cavities within crystals in which high negative pressures of up to 1.4 kbar have been achieved by isochoric cooling. For our measurements, we use fluid inclusions that cover a range of homogenisation temperatures Th from 10 to 130°C, which corresponds to fluid densities between 0.9997 and 0.9348 g/cm3. In these high-density fluid inclusions, however, spontaneous nucleation of the vapour bubble usually fails to occur upon cooling below Th and therefore, we use single ultra-short laser pulses to induce bubble nucleation for subsequent Th measurements (Krüger et al., 2007). From the Th measurements we can calculate the density and the isochore of the trapped water using the IAPWS-95 formulation (Wagner and Pruß, 2002). The extrapolation of the IAPWS-95 formulation into the metastable region displays a similar behaviour than the model proposed by Speedy, namely a negatively sloped TMD line and a spinodal curve that passes through a pressure minimum and bends towards positive pressures at low temperatures. In contrast to previous experimental studies with synthetic fluid inclusions (e.g. Green et al., 1990; Zheng et al., 1991; Alvarenga et al. 1993; Shmulovich et al., 2009), that have explored the metastable region by determining the p-T conditions of spontaneous vapour bubble nucleation to approximate the position of the spinodal, we intend to perform a series of different measurements, comprising prograde (upon heating) and retrograde (upon cooling) homogenisation temperatures Th and Thr, respectively, as well as ice nucleation and ice melting temperatures at negative pressures. The aim of these measurements is to evaluate the predictions of the IAPWS-95 formulation in the metastable region, which are poorly constrained by experimental data.To assess the thermodynamic state of the inclusion-confined water, optical micro-volume spectroscopy techniques measuring Raman and Brillouin scattering will be developed. In the first place we are aiming at Brillouin spectroscopy, which measures the speed of sound, i.e., the product of density and adiabatic compressibility. The technique of choice is optical homodyning (instead of a Fabry-Perot spectrometer), which uses stray light from the quartz sample as local oscillator. This technique became feasible only recently, thanks to the availability of high bandwidth (up to 100 GHz) optical receivers, originally developed for high-speed optical communication. One task of the Brillouin technique will be to monitor the changes of the sound velocity in the inclusions at different temperatures and (negative) pressures and thus to localize the TMD line by determining the pressure minima of the fluid isochores. The experimental data obtained will allow us to shed light on the properties of liquid water in the low-temperature metastable region and to obtain clear indications to assess the shape of the kinetic spinodal.
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