scholarly journals Preparation and Crystallization Property of Ternary Composites of WBG/AA-RCC/PP

2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
Jiang Zhu ◽  
Haitao Ni ◽  
Xiaoqing Liao ◽  
Xiang Liu
Keyword(s):  
Crystal Growth ◽  
Heterogeneous Nucleation ◽  
Lattice Plane ◽  
Mutual Inhibition ◽  
Crystallization Property ◽  
Inhibition Effect ◽  
Epitaxial Crystallization ◽  
Crystallization Behaviors

A series of ternary composites of WBG/AA-RCC/PP were prepared and their crystallization behaviors were investigated by XRD and DSC. The results indicate that WBG and AA-RCC affect the crystallization of PP matrix with a mutual inhibition effect. This effect is enhanced with increasing content of WBG and induces the growth ofβ2crystal. AA-RCC promotes the heterogeneous nucleation ofαcrystal and offers a template forαcrystal growth along a specific lattice plane and promotes the epitaxial crystallization of PP matrix, while the specific arrangedαcrystal could induce the formation ofβcrystal.

Desequilibres entre phases solides et fluides mineraux dans la petrogenese

1962 ◽  
Vol S7-IV (2) ◽  
pp. 157-164 ◽  
Author(s):  
Georges Deicha
Keyword(s):  
Crystal Growth ◽  
Solid Solutions ◽  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Fluid Solution ◽  
Secondary Intervention ◽  
The Moment

Abstract The importance of phenomena conditioned by the disequilibrium between gases, liquids, or magmas, and solid minerals is discussed. Four modes of crystal growth are capable of causing the precipitation of a crystalline species in a supersaturated or supercooled fluid solution. In homogeneous nucleation crystallization occurs at the moment when saturation is reached and only in the presence of preformed crystals of the same species. Germinal nucleation occurs when crystallization develops in conditions of disequilibrium causing the formation of minerals of the same composition but of different structure. Crystals of this mode are twinned. Metastable nucleation involves the formation of a species different in structure from the stable crystal which developed after twinning. In heterogeneous nucleation crystallization of a species has its beginning on the surface of another crystal. This introduces impurities which inhibit nucleation and crystal growth. Secondary intervention of liquid or solid solutions in the rocks also produces phenomena equally effected by disequilibrium.

scholarly journals Regularization of the Ostwald supersaturation model for Liesegang bands

2019 ◽  
Vol 475 (2228) ◽  
pp. 20190154 ◽  
Author(s):  
J. M. Duley ◽  
A. C. Fowler ◽  
I. R. Moyles ◽  
S. B. G. O'Brien
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Numerical Method ◽  
Heterogeneous Nucleation ◽  
Relaxation Mechanism ◽  
Crystal Growth Rate ◽  
Liesegang Rings ◽  
Liesegang Bands ◽  
Ill Posed

In a previous paper, we analysed the Keller–Rubinow formulation of Ostwald's supersaturation theory for the formation of Liesegang rings or Liesegang bands, and found that the model is ill-posed, in the sense that after the termination of the first crystal front growth, secondary bands form, as in the experiment, but these are numerically found to be a single grid space wide, and thus an artefact of the numerical method. This ill-posedness is due to the discontinuity in the crystal growth rate, which itself reflects the supersaturation threshold inherent in the theory. Here we show that the ill-posedness can be resolved by the inclusion of a relaxation mechanism describing an impurity coverage fraction, which physically enables the transition in heterogeneous nucleation from precipitate-free impurity to precipitate-covered impurity.

Epitaxial Crystallization Behaviors of Various Metals on a Graphene Surface

2016 ◽  
Vol 3 (14) ◽  
pp. 1500741 ◽  
Author(s):  
Dae Woo Kim ◽  
Seon Joon Kim ◽  
Hyung Ouk Choi ◽  
Hee-Tae Jung
Keyword(s):  
Graphene Surface ◽  
Epitaxial Crystallization ◽  
Crystallization Behaviors

Ion Beam Induced Amorphization and Crystallization Processes in Silicon and GaAs

1986 ◽  
Vol 74 ◽  
Author(s):  
R. G. Elliman ◽  
J. S. Williams ◽  
S. T. Johnson ◽  
E. Nygren
Keyword(s):  
Crystal Growth ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Amorphous Layer ◽  
Poor Quality ◽  
Layer By Layer ◽  
Epitaxial Crystallization ◽  
Non Linear ◽  
Thickness Layer

AbstractThin amorphous layers in crystalline Si and GaAs substates have been irradiated at selected temperatures with 1.5 MeV Ne+ ions to induce either epitaxial crystallization or amorphization. In Si, such irradiation can induce complete epitaxial crystallization of a 1000 A surface amorphous layer for temperatures typically >200°C whereas, at significantly lower temperatures, layer-by-layer amorphization results. Although epitaxial crystallization can also be stimulated in GaAs by ion irradiation at temperatures >65°C, the process is non-linear with ion dose and results in poor quality crystal growth for amorphous layers greater than a few hundred Angstroms in thickness. Layer-by-layer amorphization has not been observed in GaAs.

Barite scaling in fractures simulated with nucleation and crystal growth kinetics

2020 ◽  
Author(s):  
Morgan Tranter ◽  
Marco DeLucia ◽  
Michael Kühn
Keyword(s):  
Contact Angle ◽  
Crystal Growth ◽  
Interfacial Tension ◽  
Growth Kinetics ◽  
Heterogeneous Nucleation ◽  
Hydrothermal Systems ◽  
Fracture Aperture ◽  
In Situ Conditions ◽  
Crystal Growth Kinetics ◽  
The Impact

<p>Deep hydrothermal systems in fractured media are a potential source of geothermal energy. A key problem prevails as a consequence of utilisation that the geochemical system is perturbed and scaling may build up over time. Barite stands out as one of the most ubiquitous scaling agents in deep geothermal systems. It causes irreversible efficiency loss and may be responsible for geothermal power plants to become non-profitable. Due to complex parameter interplay and underlying uncertainties, it is imperative to utilise numerical simulations to investigate temporal and spatial precipitation effects.<br>In this work, the impact on fracture permeability in the near field of the injection well is assessed. A one-dimensional reactive transport model is set up with heterogeneous nucleation and crystal growth kinetics. In line with potential target hydrothermal systems in the North German Basin, the following parameters are considered in a sensitivity analysis: injection temperature (50 to 70 °C), pore pressure (10 to 50 MPa), fracture aperture (10<sup>-4</sup> to 10<sup>-2</sup> m), flow velocity (10<sup>-3</sup> to 10<sup>0</sup> m s<sup>-1</sup>), molar volume (50.3 to 55.6 cm<sup>3</sup> mol<sup>-1</sup>), contact angle for heterogeneous nucleation (0° to 180°), interfacial tension (0.07 to 0.134 J m<sup>-2</sup>), salinity (0.1 to 1.5 mol kgw<sup>-1</sup> NaCl), pH (5 to 7), and supersaturation (1 to 30).<br>Nucleation and consequently crystal growth can only begin if the threshold supersaturation is exceeded. Therefore, contact angle and interfacial tension are the most sensitive in terms of precipitation kinetics. If nucleation has occurred, crystal growth becomes the dominant process, which is mainly controlled by fracture aperture. Results show that fracture sealing can happen within months (33 days) and the affected range can be in the order of tens of metres (10 m). Predicting the threshold supersaturation is a crucial point in this context, as it essentially determines if barite precipitation becomes relevant.<br>The uncertainty of parameters influencing nucleation at in-situ conditions is high, emphasising the need to investigate these in more detail. The presented models suggest that barite scaling must be recognised as a serious threat if the supersaturation threshold is exceeded, in which case, larger fracture apertures could help to minimise kinetic rates.</p>

scholarly journals Review and Modeling of Crystal Growth of Atropisomers from Solutions

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 611
Author(s):  
Lotfi Derdour ◽  
Eric J. Chan ◽  
Dimitri Skliar
Keyword(s):  
Crystal Growth ◽  
Growth Inhibition ◽  
Crystal Lattice ◽  
Elevated Temperatures ◽  
Estimation Algorithm ◽  
Solvent System ◽  
Integration Step ◽  
Anisotropic Crystal ◽  
Inhibition Effect ◽  
Short Run

In this paper, theories on anisotropic crystal growth and crystallization of atropisomers are reviewed and a model for anisotropic crystal growth from solution containing slow inter-converting conformers is presented. The model applies to systems with growth-dominated crystallization from solutions and assumes that only one conformation participates in the solute integration step and is present in the crystal lattice. Other conformers, defined as the wrong conformers, must convert to the right conformer before they can assemble to the crystal lattice. The model presents a simple implicit method for evaluating the growth inhibition effect by the wrong conformers. The crystal growth model applies to anisotropic growth in two main directions, namely a slow-growing face and a fast-growing face and requires the knowledge of solute crystal face integration coefficients in both directions. A parameter estimation algorithm was derived to extract those coefficients from data about temporal concentration and crystal size during crystallization and was designed to have a short run time, while providing a high-resolution estimation. The model predicts a size-dependent growth rate and simulations indicated that for a given seed size and solvent system and for an isothermal anti-solvent addition crystallization, the seed loading and the supersaturation at seeding are the main factors impacting the final aspect ratio. The model predicts a decrease of the growth inhibition effect by the wrong conformer with increasing temperature, likely due to faster equilibration between conformers and/or a decrease of the population of the wrong conformer, if of low energy, at elevated temperatures. Finally, the model predicts that solute surface integration becomes the rate-limiting mechanism for high solute integration activation energies, resulting in no impact of the WC on the overall crystal growth process.

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