High pressure-temperature Brillouin study of liquid water: Evidence of the structural transition from low-density water to high-density water

Li, Fangfei; Cui, Qiliang; He, Zhi; Cui, Tian; Zhang, Jian; Zhou, Qiang; Zou, Guangtian; Sasaki, Shigeo

doi:10.1063/1.2102888

Cited by 57 publications

(65 citation statements)

References 30 publications

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“…These include e.g., radial distribution functions from X-ray scattering (Okhulkov et al, 1994) and neutron diffraction (Soper and Ricci, 2000), a distinct anomaly in the high-frequency sound velocity from inelastic X-ray scattering experiments (Krisch et al, 2002), the Raman shift of the O-H stretching vibration (Kawamoto et al, 2004), the sound velocity from Brillouin spectroscopy (Li et al, 2005), and the isothermal compressibility (Mirwald, 2005). The experiments indicate a transition from an open structure in low-density water (LDW) to a structure with a collapsed second coordination shell in high-density water (HDW) (Soper and Ricci, 2000).…”

Section: Introductionmentioning

confidence: 99%

Pressure-induced ion pairing in MgSO4 solutions: Implications for the oceans of icy worlds

Schmidt¹,

Manning²

2016

Geochem. Persp. Let.

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At ambient temperature, liquid water transforms from a low-density to a high-density dynamic structure at ~0.2 GPa. The transition persists in electrolyte solutions; however, its effects on solute properties are unknown. We obtained Raman spectra of 0.5-2.0 molal MgSO 4 solutions at 21 °C and 10 -4 to ~1.6 GPa. Above about 0.4 GPa, we observed an increase in the MgSO 4 contact ion pair abundance with pressure, regardless of concentration. This phenomenon contravenes the general rule that dissolved salts dissociate upon compression, and is likely caused by the structural collapse in the solvent with pressure due to increased hydrogen-bond breaking. Increasing ion association in high-pressure aqueous solutions implies that, at a given salinity, high-density water in deep, cold planetary oceans and pore waters will possess lower ionic strength and electric conductivity than previously thought. This behaviour will also lead to higher ocean salinity in the interiors of Pluto and the largest icy moons of Jupiter and Saturn, Ganymede, Callisto, and Titan, or in exoplanet water-worlds, through enhancement of submarine silicate weathering.

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Section: Introductionmentioning

confidence: 99%

Pressure-induced ion pairing in MgSO4 solutions: Implications for the oceans of icy worlds

Schmidt¹,

Manning²

2016

Geochem. Persp. Let.

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“…Since experiments can detect local changes of water structure from HDL-like to LDL-like, (e.g., [14,15]), it is possible that our prediction on the dynamic consequences of this local change may be experimentally testable.…”

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confidence: 99%

Predictions of Dynamic Behavior under Pressure for Two Scenarios to Explain Water Anomalies

2008

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Using Monte Carlo simulations and mean field calculations for a cell model of water we find a dynamic crossover in the orientational correlation time from non-Arrhenius behavior at high temperatures to Arrhenius behavior at low temperatures. This dynamic crossover is independent of whether water at very low temperature is characterized by a ''liquid-liquid critical point'' or by the ''singularity-free'' scenario. We relate to fluctuations of hydrogen bond network and show that the crossover found for for both scenarios is a consequence of the sharp change in the average number of hydrogen bonds at the temperature of the specific heat maximum. We find that the effect of pressure on the dynamics is strikingly different in the two scenarios, offering means to distinguish between them. DOI: 10.1103/PhysRevLett.100.105701 PACS numbers: 64.70.Ja, 05.40.ÿa, 64.70.qj Two different scenarios are commonly used to interpret the anomalies of water [1,2]: (i) The liquid-liquid critical point (LLCP) scenario hypothesizes that supercooled water has a liquid-liquid phase transition line that separates a low-density liquid (LDL) at low temperature T and low pressure P and a high-density liquid (HDL) at high T and P and terminates at a critical point C 0 [3]. From C 0 emanates the Widom line T W P, the line of maximum correlation length in the (T, P) plane. Response functions, such as the isobaric heat capacity C P , the coefficient of thermal expansion P , and the isothermal compressibility K T , have maxima along lines that converge toward T W P upon approaching C 0 [Figs. 1 and 2(a)]. (ii) The singularityfree (SF) scenario hypothesizes the presence of a line of temperatures of maximum density T MD P with negative slope in the (T, P) plane. As a consequence, K T and j P j have maxima that increase upon increasing P, as shown using a cell model of water. The maxima in C P do not increase with P, suggesting that there is no singularity [4] [ Fig. 2(b)].Above the homogeneous nucleation line T H P where data are available, the two scenarios predict roughly the same equilibrium phase diagram. Here we show that dynamic measurements should reveal a striking difference between the two scenarios. Specifically, the low-T dynamics depends on local structural changes, quantified by the variation in the number of hydrogen bonds, that are affected by pressure differently for each scenario. We find this result by studying-using Monte Carlo (MC) simulations and mean field calculations -a cell model which has the property that by tuning a parameter its predictions conform to those of either the LLCP or the SF scenario [5]. This cell model is based on the experimental observations that on decreasing P at constant T, or on decreasing T at constant P, (i) water displays an increasing local tetrahedrality where the sum is over NN cells, 0 < J < is the bond energy, a;b 1 if a b and a;b 0 otherwise, andwhere P k;' i denotes the sum over the IM bond indices (k, l) of the molecule i and J > 0 is the IM interaction energy with J < J, which models th...

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“…There is wide consensus on their being high-temperature manifestations of two glassy polymorphs of ice: low-density and high-density amorphous ice, respectively [2]. Raman and Brillouin spectroscopic studies have recently given conflicting predictions on the thermodynamic boundary between LDW and HDW forms [3,4]. In this Letter we present an approach to analyze different ordering regimes in water that is entirely based on entropy and which can be used to trace the LDW-HDW boundary without resorting to any a priori assumptions on the local structure of the stable liquid phase.…”

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confidence: 99%

Entropy-based measure of structural order in water

et al. 2006

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We analyze the nature of the structural order established in liquid TIP4P water in the framework provided by the multi-particle correlation expansion of the statistical entropy. Different regimes are mapped onto the phase diagram of the model upon resolving the pair entropy into its translational and orientational components. These parameters are used to quantify the relative amounts of positional and angular order in a given thermodynamic state, thus allowing a structurally unbiased definition of low-density and high-density water. As a result, the structurally anomalous region within which both types of order are simultaneously disrupted by an increase of pressure at constant temperature is clearly identified through extensive molecular-dynamics simulations. Water undergoes, under compression, a continuous structural transformation from an open, hydrogenbonded tetrahedral structure to a denser form in which the local molecular arrangement beyond the first coordination shell looks deeply modified [1]. Such two forms are ordinarily referred to as low-density and highdensity water (LDW, HDW). There is wide consensus on their being high-temperature manifestations of two glassy polymorphs of ice: low-density and high-density amorphous ice, respectively [2]. Raman and Brillouin spectroscopic studies have recently given conflicting predictions on the thermodynamic boundary between LDW and HDW forms [3,4]. In this Letter we present an approach to analyze different ordering regimes in water that is entirely based on entropy and which can be used to trace the LDW-HDW boundary without resorting to any a priori assumptions on the local structure of the stable liquid phase.Quantifying the degree of structural order present in liquids and amorphous materials is a challenging issue that has received considerable attention in the last few years [5,6,7,8]. The possibility of characterizing in a synthetic way the macroscopic state of a non-crystalline substance through some integrated measure of the overall amount of order emerging from microscopic correlations has been promisingly exploited also for complex molecular liquids such as water [9,10,11]. The method is essentially based on the identification of appropriate metrics for both positional and angular order. The thermodynamic states of the system can then be mapped onto a structural diagram, spanned by such two parameters, which can be used to obtain a direct and quantitative insight into different ordering regimes achieved by materials under cooling and/or compression. In this Letter we introduce and analyze a metric for discussing structural anomalies in water that is entirely and consistently based, for both translational and bond-orientational order, on the "fine structure" of the configurational entropy resolved through spatial correlations of increasing order.The basic relation between entropy and order can be cast in a formally rigorous statistical-mechanical framework by resorting to the multi-particle correlation expansion of the configurational entropy [12,13]. ...

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High pressure-temperature Brillouin study of liquid water: Evidence of the structural transition from low-density water to high-density water

Cited by 57 publications

References 30 publications

Pressure-induced ion pairing in MgSO4 solutions: Implications for the oceans of icy worlds

Pressure-induced ion pairing in MgSO4 solutions: Implications for the oceans of icy worlds

Predictions of Dynamic Behavior under Pressure for Two Scenarios to Explain Water Anomalies

Entropy-based measure of structural order in water

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