The Formation and Fragmentation of Periodic Bands Through Precipitation and Ostwald Ripening

Krug, Hans-Jürgen; Jacob, Karl-Heinz; Dietrich, Sabine

doi:10.1007/978-3-662-07304-9_21

Cited by 9 publications

(10 citation statements)

References 28 publications

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“…As shown previously (Krug and Jacob 1993;Krug et al 1994), the CPG model is capable of simulating several radial and lateral ring instabilities also occurring in Liesegang systems as there are: occurrences of radial fine structure within bands, lateral gaps and radial alleys of gaps within bands, apparent band branchings and transition to speckled patterns. We see in the next section that a supersaturation model without Ostwald ripening no longer shows each of the named lateral and radial instabilities, but still exhibits branching effects.…”

Section: Simulation Of Instabilities In Liesegang Systemsmentioning

confidence: 61%

“…Results of a postnucleation model (Ostwald ripening) According to our previous papers (Krug and Jacob 1993;Krug et al 1994), we want to apply the competi-tive particle growth (CPG) model after Feeney et al (1983) on simulation of Liesegang rings. For the special case of diffusion passing through a diffusion barrier, we want to compare the results of the CPG model with the results of a supersaturation model without Ostwald ripening.…”

Section: Simulation Of Instabilities In Liesegang Systemsmentioning

confidence: 99%

“…Structure formation is caused only by the competitive growth of the particles and subsequent diffusion of the solute species C. Considering a chemical reaction following the stoichiometry 2 A + B ~ C (e.g. the silver nitrate-potassium monochromate system), delivering a hardly soluble species C, we have the dimensionless equations (for details see Feeney et al 1983;Krug et al 1994):…”

Section: Simulation Of Instabilities In Liesegang Systemsmentioning

confidence: 99%

“…Also, discordant bands, i.e. band gaps, alleys of clear areas and apparently branched bands were interpreted in this framework as results of dynamic instabilities in the band-forming precipitation process (Krug and Jacob 1993;Krug et al 1994).…”

Section: Irregularities In Zebra Rock Patternsmentioning

confidence: 99%

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Morphological instabilities in pattern formation by precipitation and crystallization processes

1996

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Morphological instabilities in periodic patterns occurring both in precipitation and crystallization processes (Liesegang rings and crystal zoning) are investigated and compared with similar patterns in geological samples (zebra rocks and mud bands in snow sediments). In classical Liesegang systems, undisturbed parallel or concentric precipitation bands are emanated from even or concentric diffusion sources in homogeneous diffusion matrices of gelatine or other gels. In the case of superposing diffusion sources, sources with undulatory curvatures or local diffusion barriers there may occur several types of instabilities within the sequence of regular patterns: (a) gaps within the bands forming radial alleys free of precipitate, (b) transition from broken bands to speckled patterns and (c) apparent branching of bands linked together by so-called anastomoses. Calculations with a competitive particle growth (CPG) model show that lateral instabilities in Liesegang bands (gaps and radial alleys of gaps) are the result of Ostwald ripening effects taking place after precipitation. Apparent branching of bands or formation of anastomoses can be simulated with a prenucleation model according to Ostwald's supersaturation theory. Similar irregularities can be observed in zebra rocks (e.g. banded siderite) whose bandings are commonly explained by sequential sedimentation processes. A very different mechanism is assumed to be responsible for the origin of mud bands in snow sediments. An initially homogeneous distribution of intrinsic mud in snow sediments can be arranged into parallel bands according to a crystal zoning mechanism which is based on repeated thawing and freezing of the snow sediment due to the daily alternation of sun and darkness.

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Section: Simulation Of Instabilities In Liesegang Systemsmentioning

confidence: 61%

Section: Simulation Of Instabilities In Liesegang Systemsmentioning

confidence: 99%

Section: Simulation Of Instabilities In Liesegang Systemsmentioning

confidence: 99%

Section: Irregularities In Zebra Rock Patternsmentioning

confidence: 99%

See 2 more Smart Citations

Morphological instabilities in pattern formation by precipitation and crystallization processes

1996

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“…In addition, to the CPG model after Feeney et al (1983;see also Feeney et al 1983or Krug et al 1994, we modeled the growth of the mud assuming a continuous growth rate ( ~ 20 cm/40a = 0.5 cm/a) and the reaction coefficient depending on the Eh-value according to the amount of mine water inflow [kl =f(Eh-value)= -f*(rainfall)]. The numerical simulation provides a shape of the birnessite particle distribution in the Lautenthal mud presented in Fig.…”

Section: Discussionmentioning

confidence: 99%

Self-organization of recent rhythmic iron-manganese precipitations in underground mines in the Harz mountains

Dietrich

Jacob

1996

Geol Rundsch

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A recent early diagenetic banded iron-manganese mud has been forming underground in a closed lead-zinc mine for approximately 40 years. The processes leading to the banded structure of the precipitate were studied during a period of 2 years. Therefore, 19 physical and chemical parameters were measured regularly in short intervals. The resulting time series were analysed with respect to the data sets of the monthly chemical analyses of the descendent mine water, the daily rainfall and the mineral content. The results reveal that the precipitated material undergoes internal self-organization due to interaction of redox, colloidchemical, microbial, electrical and ripening processes, and not exclusively produced by seasonal fluctuations of material input. Thus, the primary banding of the material, caused by externally forced fluctuations of the redox conditions within the mine water, is reorganized after a short time. The finally observed bands are controlled by non-linear coupling of reaction and transport processes within the mud. A genetic model for the banded mineralization was developed and verified by numerical simulation.

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Liesegang Rings, Spirals and Helices

Dietrich

2019

Spirals and Vortices

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The Formation and Fragmentation of Periodic Bands Through Precipitation and Ostwald Ripening

Cited by 9 publications

References 28 publications

Morphological instabilities in pattern formation by precipitation and crystallization processes

Morphological instabilities in pattern formation by precipitation and crystallization processes

Self-organization of recent rhythmic iron-manganese precipitations in underground mines in the Harz mountains

Liesegang Rings, Spirals and Helices

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