Supersaturation-induced hydrothermal formation of α-CaSO4·0.5H2O whiskers

CrystEngComm ◽  
2015 ◽  
Vol 17 (10) ◽  
pp. 2141-2146 ◽  
Author(s):  
S. C. Hou ◽  
J. Wang ◽  
T. Y. Xue ◽  
W. J. Zheng ◽  
L. Xiang
Keyword(s):  
Homogeneous Nucleation ◽  
Nucleation Mechanism ◽  
Nucleation Theory ◽  
Classical Nucleation Theory

Supersaturation-induced fast transformation from CaSO4·2H2O to α-CaSO4·0.5H2O was observed and the process followed the dissolution–precipitation and homogeneous nucleation mechanism according to classical nucleation theory.

scholarly journals Homogeneous Nucleation Mechanism of NaCl in Aqueous Solutions

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 107
Author(s):  
Sun ◽  
Cui ◽  
Zhang
Keyword(s):  
Aqueous Solutions ◽  
Homogeneous Nucleation ◽  
Hydrophobic Interactions ◽  
Nucleation Mechanism ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Molecular Dynamic Simulations ◽  
Dynamic Simulations ◽  
Ion Concentrations ◽  
Step Mechanism

In this study, molecular dynamic simulations are employed to investigate the homogeneous nucleation mechanism of NaCl crystal in solutions. According to the simulations, the dissolved behaviors of NaCl in water are dependent on ion concentrations. With increasing NaCl concentrations, the dissolved Na+ and Cl- ions tend to be aggregated in solutions. In combination with our recent studies, the aggregate of dissolved solutes is mainly ascribed to the hydrophobic interactions. Different from the two-step mechanism, no barrier is needed to overcome the formation of the aggregate. In comparison with the classical nucleation theory (CNT), because of the formation of solute aggregate, this lowers the barrier height of nucleation and affects the nucleation mechanism of NaCl crystal in water.

An Analysis Of Void Nucleation In Passivated Interconnect Lines Due To Vacancy Condensation And Interface Contamination

1996 ◽  
Vol 428 ◽  
Author(s):  
R. J. Gleixner ◽  
W. D. Nix
Keyword(s):  
Growth Rate ◽  
Void Nucleation ◽  
Nucleation Mechanism ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Atomic Transport ◽  
Upper Limit ◽  
Transport Path ◽  
Hydrostatic Tensile Stress ◽  
Interconnect Lines

AbstractNucleation of voids due to vacancy condensation in passivated aluminum lines is analyzed within the context of classical nucleation theory. A discussion of sources of hydrostatic tensile stress in such lines provides a reasonable upper limit of 2 GPa. The void nucleation rate is then calculated at various sites within the line. Results suggest that nucleation rates are far too low to account for observed rates of voiding. Void nucleation at a flaw at the line/passivation interface is then considered as an alternative nucleation mechanism. Such flaws may be created by contaminants introduced during fabrication of the line. In this case, nucleation is feasible at greatly reduced stresses, well within the observed values. Furthermore, a simple model of void growth indicates that a fast atomic transport path, such as a grain boundary, must intersect the void for an appreciable growth rate. These results suggest that void nucleation in aluminum interconnect lines occurs at flaws at the sidewall of the line and that stress-induced and electromigration-induced voiding can be controlled by eliminating interfacial contamination.

Homogeneous nucleation of n-nonane and n-propanol mixtures: A comparison of classical nucleation theory and experiments

2005 ◽  
Vol 123 (24) ◽  
pp. 244502 ◽  
Author(s):  
A. I. Gaman ◽  
I. Napari ◽  
P. M. Winkler ◽  
H. Vehkamäki ◽  
P. E. Wagner ◽  
...  
Keyword(s):  
Homogeneous Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Theory And Experiments

Analytical Investigation on the Homogeneous Nucleation in a Mono-Component and Bi-Component Droplet

2019 ◽  
Author(s):  
Xi Xi ◽  
Hong Liu ◽  
Chang Cai ◽  
Ming Jia ◽  
Weilong Zhang
Keyword(s):  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
Ambient Pressure ◽  
Analytical Investigation ◽  
Bubble Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Liquid Temperature ◽  
Wide Range ◽  
Good Agreement

Abstract The work attempts to analyze the performance of homogeneous nucleation by using the non-equilibrium thermodynamics theory and the classical nucleation theory. A nucleation rate graph was constructed under a wide range of operating temperature conditions. The results indicate that the superheat limit temperature (SLT) estimated by the modified homogeneous nucleation sub-model is in good agreement with the experimental results. The nucleation rate increases exponentially with the liquid temperature rise when the liquid temperature exceeds the SLT under atmospheric pressure. The superheated temperature needed to trigger the bubble nucleation decreases with the elevated ambient pressure.

Molecular Dynamics Based Analysis of Nucleation and Surface Energy of Droplets in Supersaturated Vapors of Methane and Ethane

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Jadran Vrabec ◽  
Martin Horsch ◽  
Hans Hasse
Keyword(s):  
Molecular Dynamics ◽  
Surface Energy ◽  
Droplet Size ◽  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
First Passage Time ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Critical Droplet

Homogeneous nucleation processes are characterized by the nucleation rate and the critical droplet size. Molecular dynamics simulation is applied for studying homogeneous nucleation during condensation of supersaturated vapors of methane and ethane. The results are compared with the classical nucleation theory (CNT) and the Laaksonen–Ford–Kulmala (LFK) model that introduces the size dependence of the specific surface energy. It is shown for the nucleation rate that the Yasuoka–Matsumoto method and the mean first passage time method lead to considerably differing results. Even more significant deviations are found between two other approaches to the critical droplet size, based on the maximum of the Gibbs free energy of droplet formation (Yasuoka–Matsumoto) and the supersaturation dependence of the nucleation rate (nucleation theorem). CNT is found to agree reasonably well with the simulation results, whereas LFK leads to large deviations at high temperatures.

scholarly journals Direct calculation of ice homogeneous nucleation rate for a molecular model of water

2015 ◽  
Vol 112 (34) ◽  
pp. 10582-10588 ◽  
Author(s):  
Amir Haji-Akbari ◽  
Pablo G. Debenedetti
Keyword(s):  
Homogeneous Nucleation ◽  
Molecular Model ◽  
Direct Calculation ◽  
Nucleation Theory ◽  
Coarse Grained ◽  
Classical Nucleation Theory ◽  
Molecular Models ◽  
Microscopic Mechanism ◽  
Hexagonal Ice ◽  
Ice Leads

Ice formation is ubiquitous in nature, with important consequences in a variety of environments, including biological cells, soil, aircraft, transportation infrastructure, and atmospheric clouds. However, its intrinsic kinetics and microscopic mechanism are difficult to discern with current experiments. Molecular simulations of ice nucleation are also challenging, and direct rate calculations have only been performed for coarse-grained models of water. For molecular models, only indirect estimates have been obtained, e.g., by assuming the validity of classical nucleation theory. We use a path sampling approach to perform, to our knowledge, the first direct rate calculation of homogeneous nucleation of ice in a molecular model of water. We use TIP4P/Ice, the most accurate among existing molecular models for studying ice polymorphs. By using a novel topological approach to distinguish different polymorphs, we are able to identify a freezing mechanism that involves a competition between cubic and hexagonal ice in the early stages of nucleation. In this competition, the cubic polymorph takes over because the addition of new topological structural motifs consistent with cubic ice leads to the formation of more compact crystallites. This is not true for topological hexagonal motifs, which give rise to elongated crystallites that are not able to grow. This leads to transition states that are rich in cubic ice, and not the thermodynamically stable hexagonal polymorph. This mechanism provides a molecular explanation for the earlier experimental and computational observations of the preference for cubic ice in the literature.

Homogeneous nucleation of NaCl in supersaturated solutions

2021 ◽  
Author(s):  
Cintia Pulido Lamas ◽  
Jorge R. Espinosa ◽  
María Martín Conde ◽  
Jorge Ramirez ◽  
Pablo Montero de Hijes ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Homogeneous Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Approximate Approach ◽  
Seeding Method ◽  
Dynamics Simulations ◽  
Supersaturated Solutions

The Seeding method is an approximate approach to investigate nucleation that combines molecular dynamics simulations with classical nucleation theory. This technique has been successfully implemented in a broad range of...

scholarly journals Imaging the Homogeneous Nucleation During the Melting of Superheated Colloidal Crystals

Science ◽  
2012 ◽  
Vol 338 (6103) ◽  
pp. 87-90 ◽  
Author(s):  
Ziren Wang ◽  
Feng Wang ◽  
Yi Peng ◽  
Zhongyu Zheng ◽  
Yilong Han
Keyword(s):  
Phase Transitions ◽  
Homogeneous Nucleation ◽  
Critical Size ◽  
Colloidal Crystals ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Nucleation Process ◽  
Particle Exchange ◽  
Superheat Limit ◽  
Shape And Size

The nucleation process is crucial to many phase transitions, but its kinetics are difficult to predict and measure. We superheated and melted the interior of thermal-sensitive colloidal crystals and investigated by means of video microscopy the homogeneous melting at single-particle resolution. The observed nucleation precursor was local particle-exchange loops surrounded by particles with large displacement amplitudes rather than any defects. The critical size, incubation time, and shape and size evolutions of the nucleus were measured. They deviate from the classical nucleation theory under strong superheating, mainly because of the coalescence of nuclei. The superheat limit agrees with the measured Born and Lindemann instabilities.

Kinetic Analysis on Nanoparticle Condensation by Molecular Dynamics

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Donguk Suh ◽  
Kenji Yasuoka
Keyword(s):  
Molecular Dynamics ◽  
Growth Rate ◽  
Free Energy ◽  
Kinetic Analysis ◽  
Seed Size ◽  
Homogeneous Nucleation ◽  
Cluster Formation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Seed Particle

Condensation on a cubic seed particle was simulated by classical molecular dynamics (MD). Seed size and supersaturation ratio of the system were the factors that were examined in order to observe the effects of the dimension of seeds and thermodynamic conditions. Two stages of nucleation were observed in the phenomenon, where the first stage is from the seed growth and the second from homogeneous nucleation. Therefore, the nucleation rate and growth rate were each calculated by the Yasuoka–Matsumoto (YM) method. As the seed size increased, the growth rate decreased, but there was no clear seed influence on the homogeneous nucleation characteristics. Besides, the classical nucleation theory (CNT), cluster formation free energy and kinetic analysis were conducted. The free energy in the exponential term of the classical nucleation theory and that obtained from the cluster formation free energy showed different characteristics.

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