Keimbildungsgeschwindigkeit und OSTWALDsche Stufenregel

Stranski, I. N.; Totomanow, D.

doi:10.1515/zpch-1933-16335

Cited by 189 publications

(82 citation statements)

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“…This rule states that the phase that nucleates from the melt need not be the most stable solid phase, but is rather the one that is closest in free energy to the metastable liquid phase. Stranski and Totomanow [21] re-examined this rule and argued that the nucleated phase is the one that has the lowest nucleation barrier. Alexander and McTague [22] extended the Landau freeenergy expansion to freezing transitions that are weakly first order and concluded from general symmetry considerations that, in three dimensions, formation of the body-centred cubic (bcc) nuclei is uniquely favoured for simple fluids.…”

Section: Homogeneous Nucleationmentioning

confidence: 99%

Crystallization of weakly charged colloidal spheres: a numerical study

Auer

Frenkel

2002

J. Phys.: Condens. Matter

111

122

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We report a numerical study of crystal nucleation in a system of weakly charged colloids. The interaction between the colloids is approximated by a repulsive hard-core Yukawa potential. We studied the dependence of the nucleation barrier and the nucleation rate on supersaturation as a function of both contact value and range of the interaction potential. We find that, at the same volume fraction, nucleation is much faster for these soft colloids than for hard spheres. This is partly because fluid-solid coexistence in charged colloids occurs at lower volume fractions than for hard spheres. But, in addition, the softness of the potential has a pronounced direct effect on the nucleation barrier through a lowering of the solid-liquid surface free energy. Moreover, the softness of the potential directly affects the pathway for crystal nucleation: even when the stable crystal phase has a face-centred cubic structure, we find that the initial crystal nuclei have a bcc structure.

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Section: Homogeneous Nucleationmentioning

confidence: 99%

Crystallization of weakly charged colloidal spheres: a numerical study

Auer

Frenkel

2002

J. Phys.: Condens. Matter

111

122

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“…According to this rule, a metastable system does not have to relax directly into the most stable state. If there is another metastable state, the probability that the system will visit this state depends on the height of the free energy barrier between the states 40 . For an undercooled LJ system, the most stable state is the facecentered cubic (fcc) structure, but the free energy barrier between the liquid and the metastable body-centered cubic (bcc) crystal is sufficiently low, such that the fluid may first freeze into the bcc structure and then relax into the more stable fcc structure.…”

Section: Mean Recurrence Timesmentioning

confidence: 99%

Caveats of mean first-passage time methods applied to the crystallization transition: Effects of non-Markovianity

Jungblut

Dellago

2015

The Journal of Chemical Physics

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Using the crystallization transition in a Lennard-Jones fluid as example, we show that mean first-passage time based methods may underestimate the reaction rates. We trace the reason of this deficiency back to the non-Markovian character of the dynamics caused by the projection to a poorly chosen reaction coordinate. The non-Markovianity of the dynamics becomes apparent in the behavior of the recurrence times.

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“…The squeezed seeds cause a comparatively smaller increase of the reaction rate, but also here, the bcc-structured seed raises the rate more than the fcc-structured one. In terms of Ostwald's step rule 20,21 , which relates the transition path to the height of the free energy barrier the system has to overcome to leave the metastable state, we can connect the behaviour of our system to the free energy landscape underlying the reaction. The presence of both seeds lowers the free energy barrier to the corresponding state, but then the bcc structure still has to transform to the fcc phase.…”

Section: A Crystal Nucleation Ratesmentioning

confidence: 99%

On the reaction coordinate for seeded crystallisation

Jungblut

Dellago

2015

Molecular Physics

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Small pre-structured seeds introduced into an undercooled fluid are known to increase the crystal nucleation rate by some orders of magnitude, if the structure of the seeds is commensurate with the bulk crystalline phase. The presence of such seeds also alters the crystallisation mechanism by favouring particular structures at the early stages of the nucleation process. Here, we study with computer simulations the effect of small face-centred cubic and body-centred cubic seeds on the crystallisation of a Lennard-Jones liquid in the strongly undercooled regime. We find that seeds with body-centred cubic structure lead to a larger enhancement of the crystallisation rate than facecentred cubic seeds. An analysis of recurrence times reveals that the size of the largest crystalline cluster used as reaction coordinate is affected by pronounced memory effects, which depend on the particular seed structure and point to the importance of structural information in the definition of a good reaction coordinate for crystallisation.

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Keimbildungsgeschwindigkeit und OSTWALDsche Stufenregel

Cited by 189 publications

References 0 publications

Crystallization of weakly charged colloidal spheres: a numerical study

Crystallization of weakly charged colloidal spheres: a numerical study

Caveats of mean first-passage time methods applied to the crystallization transition: Effects of non-Markovianity

On the reaction coordinate for seeded crystallisation

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