Frustration vs Prenucleation: Understanding the Surprising Stability of Supersaturated Sodium Thiosulfate Solutions

Reichenbach, Judith; Wynne, Klaas

doi:10.1021/acs.jpcb.8b04112

Cited by 24 publications

(40 citation statements)

References 52 publications

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“…Similar to the disordered pre-nucleation NaCl clusters here, recent optical Kerr-effect spectroscopy experiments confirmed the presence of large metastable ion clusters in supersaturated sodium thiosulfate solutions. 53 Based on the above arguments, the spinodal observed from the electrolyte chemical potential vs. concentration curve (Fig. 1) identifies the stability limit of the aqueous NaCl solution, with respect to concentration fluctuations, not crystallization, and corresponds to the spontaneous formation of amorphous salt clusters, i.e.…”

Section: Phase a Similar Picture For Binary Lj Solutions Has Been Prmentioning

confidence: 93%

Nucleation in aqueous NaCl solutions shifts from 1-step to 2-step mechanism on crossing the spinodal

Jiang

Debenedetti

Panagiotopoulos

2019

The Journal of Chemical Physics

113

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In this work, we use large-scale molecular dynamics simulations coupled to free energy calculations to identify for the first time a limit of stability (spinodal) and a change in the nucleation mechanism in aqueous NaCl solutions. This is a system of considerable atmospheric, geological and technical significance. We find that the supersaturated metastable NaCl solution reaches its limit of stability at sufficiently high salt concentrations, as indicated by the composition dependence of the salt chemical potential, indicating the transition to a phase separation by spinodal decomposition. However, the metastability limit of the NaCl solution does not correspond to spinodal decomposition with respect to crystallization. We find that beyond this spinodal, a liquid/amorphous separation occurs in the aqueous solution, whereby the ions first form disordered clusters. We term these clusters as "amorphous salt". We also identify a transition from one-to two-step crystallization mechanism driven by a spinodal. In particular, crystallization from aqueous NaCl solution beyond the spinodal is a two-step process, in which the ions first phase-separate into disordered amorphous salt clusters, followed by the crystallization of ions in the amorphous salt phase. In contrast, in the aqueous NaCl solution at concentrations lower than the spinodal, crystallization occurs via a one-step process, as the ions aggregate directly into crystalline nuclei. The change of mechanism with increasing supersaturation underscores the importance of an accurate determination of the driving force for phase separation. The study has broader implications on the mechanism for nucleation of crystals from solutions at high supersaturations.

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Section: Phase a Similar Picture For Binary Lj Solutions Has Been Prmentioning

confidence: 93%

Nucleation in aqueous NaCl solutions shifts from 1-step to 2-step mechanism on crossing the spinodal

Jiang

Debenedetti

Panagiotopoulos

2019

The Journal of Chemical Physics

113

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“…SI7). Liquid 1 has a low-frequency spectrum typical of organic liquids 24,25 with a smooth band due to molecular librations peaking at 60 cm -1 (2 THz) as confirmed by optical Kerr-effect spectroscopy ( Fig. SI8 and Fig.…”

Section: Vibrational Spectroscopymentioning

confidence: 64%

“…Ultrafast optical Kerr-effect (OKE) data were taken in purpose-built time-domain pump−probe set-up as described previously. 24,25 Very briefly, OKE data are taken in an ultrafast pump−probe spectroscopy setup using a Micra laser (Coherent) yielding 800-nm 20-22 fs laser pulses at a repetition rate of 82 MHz. A maximum delay time of 1 ns resulted in spectral coverage down to 1 GHz in the frequency domain after numerical Fourier transformation.…”

Section: Optical Kerr-effect Spectroscopymentioning

confidence: 99%

Polyamorphism Mirrors Polymorphism in the Liquid–Liquid Transition of a Molecular Liquid

Walton¹,

Bolling²,

Farrell³

et al. 2019

Preprint

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Liquid-liquid transitions between two amorphous phases in a single-component liquid (polyamorphism)have defied explanation and courted controversy. All known examples of liquid-liquid transitions have been observed in the supercooled liquid suggesting an intimate connection with vitrification and locally favoured structures inhibiting crystallisation. However, there is precious little information about the local molecular packing in supercooled liquids meaning that the order parameter of the transition is still unknown. Here, we investigate the liquid-liquid transition in triphenyl phosphite and show that it is caused by the competition between liquid structures that mirror two crystal polymorphs. The liquidliquid transition is found to be between a geometrically frustrated liquid to a dynamically frustrated glass. These results indicate a general link between polymorphism and polyamorphism and will lead to a much greater understanding of the physical basis of liquid-liquid transitions and allow the discovery of other examples.

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“…21,22 Fourier-transform infrared spectroscopy (FTIR) and femtosecond infrared pump-probe spectroscopy 23,24 were used to measure the temperature-dependent IR spectrum and the vibrational excited-state lifetimes. Ultrafast optical Kerr-effect (OKE) spectroscopy [25][26][27][28] was used to measure the temperature-dependent depolarized Raman spectrum of a eutectic solution of LiSCN in water (LiSCN:5.8H 2 O).…”

Section: Introductionmentioning

confidence: 99%

Experimental observation of nanophase segregation in aqueous salt solutions around the predicted liquid–liquid transition in water

Lane

Reichenbach

Farrell

et al. 2020

Phys. Chem. Chem. Phys.

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Frustration vs Prenucleation: Understanding the Surprising Stability of Supersaturated Sodium Thiosulfate Solutions

Cited by 24 publications

References 52 publications

Nucleation in aqueous NaCl solutions shifts from 1-step to 2-step mechanism on crossing the spinodal

Nucleation in aqueous NaCl solutions shifts from 1-step to 2-step mechanism on crossing the spinodal

Polyamorphism Mirrors Polymorphism in the Liquid–Liquid Transition of a Molecular Liquid

Experimental observation of nanophase segregation in aqueous salt solutions around the predicted liquid–liquid transition in water

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