A transferable force-field for alkali metal nitrates

Fantauzzo, Vittoria; Yeandel, Stephen R.; Freeman, Colin L.; Harding, John H.

doi:10.1088/2399-6528/ac6e2b

Cited by 5 publications

(3 citation statements)

References 62 publications

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“…These were subsequently compared with experimental values (Table S1 in the Supporting Information). 52 The values of Fantauzzo et al 53 were selected for Na + , which are force fields for the solid-aqueous phase of alkali nitrates. The K + force field is from Wang et al, 54 who developed them for a concentrated KNO 3 aqueous solution using neutron pair distribution function (PDF) analysis coupled with classical MD simulations.…”

Section: Methodsmentioning

confidence: 99%

Molecular Mechanisms of Sorbed Ion Effects during Boehmite Particle Aggregation

Liu,

Rampal,

Nakouzi

et al. 2024

Langmuir

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Classical theories of particle aggregation, such as Derjaguin−Landau−Verwey−Overbeek (DLVO), do not explain recent observations of ion-specific effects or the complex concentration dependence for aggregation. Thus, here, we probe the molecular mechanisms by which selected alkali nitrate ions (Na + , K + , and NO 3 − ) influence aggregation of the mineral boehmite (γ-AlOOH) nanoparticles. Nanoparticle aggregation was analyzed using classical molecular dynamics (CMD) simulations coupled with the metadynamics rare event approach for stoichiometric surface terminations of two boehmite crystal faces. Calculated free energy landscapes reveal how electrolyte ions alter aggregation on different crystal faces relative to pure water. Consistent with experimental observations, we find that adding an electrolyte significantly reduces the energy barrier for particle aggregation (∼3−4×). However, in this work, we show this is due to the ions disrupting interstitial water networks, and that aggregation between stoichiometric (010) basal−basal surfaces is more favorable than between (001) edge−edge surfaces (∼5−6×) due to the higher interfacial water densities on edge surfaces. The interfacial distances in the interlayer between aggregated particles with electrolytes (∼5−10 Å) are larger than those in pure water (a few Ångstroms). Together, aggregation/disaggregation in salt solutions is predicted to be more reversible due to these lower energy barriers, but there is uncertainty on the magnitudes of the energies that lead to aggregation at the molecular scale. By analyzing the peak water densities of the first monolayer of interstitial water as a proxy for solvent ordering, we find that the extent of solvent ordering likely determines the structures of aggregated states as well as the energy barriers to move between them. The results suggest a path for developing a molecular-level basis to predict the synergies between ions and crystal faces that facilitate aggregation under given solution conditions. Such fundamental understanding could be applied extensively to the aggregation and precipitation utilization in the biological, pharmaceutical, materials design, environmental remediation, and geological regimes.

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Section: Methodsmentioning

confidence: 99%

Molecular Mechanisms of Sorbed Ion Effects during Boehmite Particle Aggregation

Liu,

Rampal,

Nakouzi

et al. 2024

Langmuir

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“…The (NO) 2 MCl 6 (M = Sn, Ti, V) systems contain the nitrosonium groups surrounded by MCl 6 2– units similar to that in the K 2 PtCl 6 type structure. The ordering of NO+ groups was found for them at 231, 199, and 236.5 K for Sn, Ti, and V, respectively. − There is a remarkable polymorphism observed in the ANO 3 nitrates of the alkali metals (A = Na, K, Rb) . The NaNO 3 undergoes order–disorder transition at T C = 548 K which occurs due to the continuous planar rotation of the nitrate group at T > T C . , The KNO 3 passes though the order–disorder transition at 401 K due to the increase of the large amplitude librations of the nitrate anions along with large amplitude oscillations of the potassium ions along the c -axis.…”

Section: Introductionmentioning

confidence: 97%

“…5−7 There is a remarkable polymorphism observed in the ANO 3 nitrates of the alkali metals (A = Na, K, Rb). 8 The NaNO 3 undergoes order−disorder transition at T C = 548 K which occurs due to the continuous planar rotation of the nitrate group at T > T C . 9,10 The KNO 3 passes though the order−disorder transition at 401 K due to the increase of the large amplitude librations of the nitrate anions along with large amplitude oscillations of the potassium ions along the c-axis.…”

Section: ■ Introductionmentioning

confidence: 99%

Sequence of Structural and Magnetic Phase Transitions in (NO)Mn₆(NO₃)₁₃

Vorobyova,

Morozov,

Vasilchikova

et al. 2024

Inorg. Chem.

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New nitrosonium manganese(II) nitrate, (NO)Mn6(NO3)13, has been synthesized and structurally characterized. In the temperature range of 45–298 K, the crystal is hexagonal (centrosymmetric sp. gr. P63/m). Mn2+ ions are assembled into tubes along axis c with both NO3 – filling and coating. The nitrosonium cation is located in the framework cavity and is disordered by a 3-fold axis. At the temperature T S1 = 190 K, a structural phase transition related to the libration of the intertube NO3 group and a small variation of Mn polyhedron is observed. Moreover, the anomalies in physical properties of (NO)Mn6(NO3)13 allow suggesting that ordering of NO+ units occurs at low temperatures. The antiferromagnetic ordering in this compound is preceded by the formation of a short-range correlation regime at about 25 K and takes place in two steps at T N1 = 12.0 K and T N2 = 8.4 K.

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Ion Correlations Decrease Particle Aggregation Rate by Increasing Hydration Forces at Interfaces

Butreddy,

Heo,

Rampal

et al. 2024

ACS Nano

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The connection between solution structure, particle forces, and emergent phenomena at solid–liquid interfaces remains ambiguous. In this case study on boehmite aggregation, we established a connection between interfacial solution structure, emerging hydration forces between two approaching particles, and the resulting structure and kinetics of particle aggregation. In contrast to expectations from continuum-based theories, we observed a nonmonotonic dependence of the aggregation rate on the concentration of sodium chloride, nitrate, or nitrite, decreasing by 15-fold in 4 molal compared to 1 molal solutions. These results are accompanied by an increase in repulsive hydration forces and interfacial oscillatory features from 0.27–0.31 nm in 0.01 molal to 0.38–0.52 nm in 2 molal. Moreover, molecular dynamics (MD) simulations indicated that these changes correspond to enhanced ion correlations near the interface and produced loosely bound aggregates that retain electrolyte between the particles. We anticipate that these results will enable the prediction of particle aggregation, attachment, and assembly, with broad relevance to interfacial phenomena.

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A transferable force-field for alkali metal nitrates

Cited by 5 publications

References 62 publications

Molecular Mechanisms of Sorbed Ion Effects during Boehmite Particle Aggregation

Molecular Mechanisms of Sorbed Ion Effects during Boehmite Particle Aggregation

Sequence of Structural and Magnetic Phase Transitions in (NO)Mn₆(NO₃)₁₃

Ion Correlations Decrease Particle Aggregation Rate by Increasing Hydration Forces at Interfaces

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A transferable force-field for alkali metal nitrates

Cited by 5 publications

References 62 publications

Molecular Mechanisms of Sorbed Ion Effects during Boehmite Particle Aggregation

Molecular Mechanisms of Sorbed Ion Effects during Boehmite Particle Aggregation

Sequence of Structural and Magnetic Phase Transitions in (NO)Mn6(NO3)13

Ion Correlations Decrease Particle Aggregation Rate by Increasing Hydration Forces at Interfaces

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Product

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Sequence of Structural and Magnetic Phase Transitions in (NO)Mn₆(NO₃)₁₃