scholarly journals Secondary Nucleation by Interparticle Energies. II. Kinetics

2021 ◽  
Author(s):  
Byeongho Ahn ◽  
Luca Bosetti ◽  
Marco Mazzotti
Keyword(s):  
Secondary Nucleation

Continuous Precipitation of Lead Iodide

1994 ◽  
Vol 59 (7) ◽  
pp. 1503-1510
Author(s):  
Stanislav Žáček ◽  
Jaroslav Nývlt
Keyword(s):  
Growth Rate ◽  
Particle Size ◽  
Crystal Size ◽  
Crystal Growth Rate ◽  
Laboratory Model ◽  
Lead Iodide ◽  
Secondary Nucleation ◽  
Equimolar Ratio ◽  
Continuous Precipitation ◽  
The Mean

Lead iodide was precipitated from aqueous solutions of 0.015 - 0.1 M Pb(NO3)2 and 0.03 - 0.2 M KI in the equimolar ratio using a laboratory model of a stirred continuous crystallizer at 22 °C. After reaching the steady state, the PbI2 crystal size distribution was measured sedimentometrically and the crystallization kinetics was evaluated based on the mean particle size. Both the linear crystal growth rate and the nucleation rate depend on the specific output of the crystallizer. The system crystallization constant either points to a significant effect of secondary nucleation by the mechanism of contact of the crystals with the stirrer blade, or depends on the concentrations of the components added due to the micromixing mechanism.

Batch Crystallization with Crystals Attrition

1993 ◽  
Vol 58 (8) ◽  
pp. 1855-1860 ◽  
Author(s):  
Jaroslav Nývlt ◽  
Stanislav Žáček
Keyword(s):  
Mathematical Model ◽  
Calcium Sulfate ◽  
Crystal Size ◽  
Theoretical Description ◽  
Secondary Nucleation ◽  
Batch Crystallization ◽  
Batch Time ◽  
The Mean

The dependence of the mean crystal size of the products from batch crystallizers on the batch time occasionally exhibits a maximum, which can be explained by secondary nucleation due to the attrition of crystals. A kinetic equatation of nucleation, comprising a term for crystal attrition, can be used for the theoretical description of such behaviour. A mathematical model of a batch crystallizer with crystal attrition has been verified on the calcium sulfate precipitation.

On the morphology of melt-crystallized polyethylene - II. Lamellae and their crystallization conditions

1981 ◽  
Vol 377 (1768) ◽  
pp. 39-60 ◽  
Keyword(s):  
Molecular Mass ◽  
Crystallization Temperature ◽  
Lamellar Thickness ◽  
Kinetic Regime ◽  
Secondary Nucleation ◽  
Constant Multiple ◽  
Linear Polyethylene ◽  
Simple Assumption ◽  
Crystallization Conditions ◽  
Prevalent Form

The microstructure of melt-crystallized linear polyethylene has been correlated with the variables of crystallization for most readily attainable conditions. All samples are filled with well defined lamellae with an aver­age chain inclination of about 35° to lamellar normals. The lamellar thickness depends upon supercooling rather than directly on crystalliza­tion temperature, which indicates that it is a kinetically determined quantity. The simple assumption that it is a constant multiple of the height given by secondary nucleation is, however, incorrect. Lamellar profiles depend only upon the crystallization temperature and molecular mass of the polyethylene concerned. They are independent of the extent of spherulitic development and are not determined solely by the kinetic régime in which crystals grow. Dominant S-shaped lamellae (Ss) and their associated subsidiary platelets are, nevertheless, the prevalent form for crystallization within régime II, i. e. in most cases of practical import­ance. The distinction between dominant and subsidiary lamellae is linked to fractional crystallization. At low supercoolings it is shown that shorter molecules are concentrated within subsidiary lamellae, and the trend to separate later-crystallizing species is likely to persist, to a lesser degree, even to quenched samples. With the use of added branched molecules this has been demonstrated to occur. The consequences of spatial segre­gation are likely to include increased vulnerability to mechanical and environmentally induced failure.

scholarly journals Methionine-stabilized nonclassical growth within self-assembled de novo gold nanoparticles in conjunction with secondary nucleation inhibition

2021 ◽  
Author(s):  
Jitendra Sahu ◽  
Shahbaz Lone ◽  
Kalyan Sadhu
Keyword(s):  
Self Assembly ◽  
De Novo ◽  
Noble Metal Nanoparticles ◽  
Secondary Nucleation ◽  
Unique Case ◽  
Primary Particles ◽  
Growth Reaction ◽  
Aurophilic Interaction ◽  
Key Steps

Abstract The key steps for seed mediated growth of noble metal nanoparticles involve primary and secondary nucleation, which depends upon the energy barrier and ligand supersaturation standards of the medium. Herein we report the unique case of methionine (Met) controlled growth reaction, which rather proceeds via impeding secondary nucleation in presence of citrate stabilized gold nanoparticle (AuNP). The interaction between freshly generated Au+ and thioether group of Met in the medium restricts the secondary nucleation process involving further Au+ reduction. This incomplete conversion of Au+ results in a significant enhancement of the zeta (ζ) potential even at low concentration of Met. Furthermore, the aurophilic interaction of Au+ controls the self-assembly process of the in situ generated emissive nucleated particles. Nucleation of primary particles on seed surface, their segregation and time dependent conversion to larger particles within self-assembly confirm the nonclassical growth, which has further been explored with Met containing bio-inspired peptides.

Laser-Assisted Biomimetic Process for Calcium Phosphate Coating on a Hydroxyapatite Ceramic

2012 ◽  
Vol 529-530 ◽  
pp. 217-222 ◽  
Author(s):  
Ayako Oyane ◽  
Ikuko Sakamaki ◽  
Yoshiki Shimizu ◽  
Kenji Kawaguchi ◽  
Yu Sogo ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Nucleation And Growth ◽  
Calcium Phosphate Coating ◽  
Dependent Manner ◽  
Secondary Nucleation ◽  
Hydroxyapatite Ceramic ◽  
Ethylene Vinyl Alcohol ◽  
Coating Technique ◽  
Laser Absorption ◽  
Dental Applications

The present authors recently developed a new calcium phosphate (CaP) coating technique on an ethylene-vinyl alcohol copolymer substrate utilizing a laser-assisted biomimetic (LAB) process. In the present study, the LAB process was applied to a sintered hydroxyapatite (sHA) substrate for CaP coating. The LAB process was carried out by irradiating the sHA substrate immersed in a supersaturated CaP solution with a low-energy Nd-YAG pulsed laser. Within 30 min of irradiation, contiuous CaP layers with different morphologies were successfully formed on the laser-irradiated sHA surface. A submicron cavernous structure of the CaP layer was developed into a micron flake-like structure as the laser power increased from 1 to 3 W. This result suggests that the secondary nucleation and growth of CaP crystals were accelerated by laser irradiation in a power-dependent manner. Laser absorption by the sHA substrate and the resulting increase in ambient temperature locally near the surface should be responsible for the accelerated CaP nucleation and growth. The present CaP coating technique using the LAB process is simple and quick, hence it would be useful in orthopedic and dental applications as an on-demand surface-functionalization method for biomaterials consisting of sHA.

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