Genericity of confined chemical garden patterns with regard to changes in the reactants (original) (raw)
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Spiral precipitation patterns in confined chemical gardens
Proceedings of the National Academy of Sciences, 2014
Chemical gardens are mineral aggregates that grow in three dimensions with plant-like forms and share properties with self-assembled structures like nanoscale tubes, brinicles or chimneys at hydrothermal vents. The analysis of their shapes remains a challenge, as their growth is influenced by osmosis, buoyancy and reaction-diffusion processes. Here we show that chemical gardens grown by injection of one reactant into the other in confined conditions feature a wealth of new patterns including spirals, flowers, and filaments. The confinement decreases the influence of buoyancy, reduces the spatial degrees of freedom and allows analysis of the patterns by tools classically used to analyze two-dimensional patterns. Injection moreover allows the study in controlled conditions of the effects of variable concentrations on the selected morphology. We illustrate these innovative aspects by characterizing quantitatively, with a simple geometrical model, a new class of self-similar logarithmic spirals observed in a large zone of the parameter space.
Journal of colloid and …, 2002
Chemical gardens are the plant-like structures formed upon placing together a soluble metal salt, often in the form of a seed crystal, and an aqueous solution of one of many anions, often sodium silicate. We have observed the development of chemical gardens with Mach-Zehnder interferometry. We show that a combination of forced convection from osmosis and free convection from buoyancy, together with chemical reaction, is responsible for their morphogenesis. C 2002 Elsevier Science (USA)
Pattern of a confined chemical garden controlled by injection speed
Physical Review E
Pattern of confined chemical garden was controlled by the speed of injected fluid, and their mechanism is discussed. A confined chemical garden system was constructed where an aqueous solution of cobalt chloride was injected into a cell filled with sodium silicate solution. The reaction of these two solutions resulted in the formation of precipitation. The viscosities of the prepared aqueous solutions were set to be similar in order to rule out the possibility of Saffman-Taylor instability. The injection front showed three distinctive patterns: algaes, shells, and filaments, which were dependent on injection speed. The injection pressure and the spatio-temporal pattern of the injected fluid were measured, and a significant increase in the injection pressure was observed when the filament pattern appeared, which indicated the existence of thin lubrication layer between the precipitation and the substrate. The filament pattern was further analyzed quantitatively, and the number of active filaments was determined to be proportional to the injection speed. A mathematical model was constructed that considered both the viscous effect from the thin luburiation layer and the Laplace pressure. This model successfully reproduced the characteristic filament dynamics. II. EXPERIMENTAL SYSTEM Water was purified using a Millipore Milli-Q system.
Oscillations of a chemical garden
Physical Review E, 2008
When soluble metal salts are placed in a silicate solution, chemical gardens grow. These gardens are treelike structures formed of long, thin, hollow tubes. Here we study one particular case: a calcium nitrate pellet in a solution of sodium trisilicate. We observe that tube growth results from a relaxation oscillation. The average period and the average growth rate are approximately constant for most of the structures growth. The period does fluctuate from cycle to cycle, with the oscillation amplitude proportional to the period. Based on our observations, we develop a model of the relaxation oscillations which calculates the average oscillation period and the average tube radius in terms of fundamental membrane parameters. We also propose a model for the average tube growth rate. Predictions are made for future experiments.
Chemical-Garden Formation, Morphology, and Composition. I. Effect of the Nature of the Cations
Langmuir, 2011
We have grown chemical gardens in different sodium silicate solutions from several metal-ion salts-calcium chloride, manganese chloride, cobalt chloride, and nickel sulfate-with cations from period 4 of the periodic table. We have studied their formation process using photography, examined the morphologies produced using scanning electron microscopy (SEM), and analyzed chemical compositions using X-ray powder diffraction (XRD) and energy dispersive X-ray analysis (EDX) to understand better the physical and chemical processes involved in the chemical-garden reaction. We have identified different growth regimes in these salts that are dependent on the concentration of silicate solution and the nature of the cations involved.
Flower Patterns in a Growing Active Chemical Medium
The Journal of Physical Chemistry A, 1997
A simple experimental model on the basis of the Belousov-Zhabotinsky (BZ) reaction was produced for the study of wave patterns in a spatially growing excitable medium. A drop of sulfuric acid, placed onto a millipore filter soaked with low-acid BZ solution, expanded with time and made the system excitable. New patterns of flower-like propagation were observed at the frontier of a growing excitable spot. Initially plain circular wave fronts, when expanding, changed to a crown of petal-like propagating fragments of excitation waves. The overall symmetry of the system spontaneously changed with time.
Growing a Chemical Garden at the Air–Fluid Interface
Langmuir, 2016
Here we grow chemical gardens using a novel, quasi two-dimensional, experimental configuration. Buoyant calcium chloride solution is pumped onto the surface of sodium silicate solution. The solutions react to form a precipitation structure on the surface. Initially, an open channel forms that grows in a spiral. This transitions to radially spreading and branching fingers, which typically oscillate in transparency as they grow. The depth of the radial spreading, and the fractal dimension of the finger growth, are surprisingly robust, being insensitive to the pumping rate. The curvature of the channel membrane and the depth of the radially spreading solution can be explained in terms of the solution densities and the interfacial tension across the semipermeable membrane. These unusually beautiful structures provide new insights into the dynamics of precipitation structures and may lead to new technologies where structures are grown instead of assembled.
Pattern of confined chemical garden controlled by injection speed
2017
Pattern of confined chemical garden was controlled by the speed of injected fluid, and their mechanism is discussed. A confined chemical garden system was constructed where an aqueous solution of cobalt chloride was injected into a cell filled with sodium silicate solution. The reaction of these two solutions resulted in the formation of precipitation. The viscosities of the prepared aqueous solutions were set to be similar in order to rule out the possibility of Saffman-Taylor instability. The injection front showed three distinctive patterns: algaes, shells, and filaments, which were dependent on injection speed. The injection pressure and the spatio-temporal pattern of the injected fluid were measured, and a significant increase in the injection pressure was observed when the filament pattern appeared, which indicated the existence of thin lubrication layer between the precipitation and the substrate. The filament pattern was further analyzed quantitatively, and the number of act...