scholarly journals Multi-Step Crystallization and Chemical Evolution of Sodium Yttrium Fluoride

2021 ◽  
Author(s):  
Peter Pauzauskie ◽  
Alexander Bard ◽  
R. Greg Felsted ◽  
Abbie Ganas ◽  
Anupum Pant ◽  
...  
Keyword(s):  
Solid Phase ◽  
Nucleation And Growth ◽  
Intermediate Step ◽  
Gradual Change ◽  
Fluoride Ions ◽  
Aqueous Synthesis ◽  
Yttrium Fluoride ◽  
New Perspective ◽  
Step Mechanism ◽  
Step Crystallization

Abstract Two-step crystallization mechanisms based on spinodal decomposition followed by nucleation are commonly observed both in the laboratory and in nature. While this pathway may require chemical reactions, subsequent nucleation and growth are often considered as separate, discrete events from the reaction itself. Recent work has also shown a distinct intermediate step involving the formation of an amorphous aggregate. Here we report a novel four-step mechanism in the aqueous synthesis of sodium yttrium fluoride involving 1) the segregation of aqueous ions into a dense liquid phase, 2) the formation of an amorphous aggregate, 3) nucleation of a cubic YF3 phase, and 4) subsequent solid-state diffusion of sodium and fluoride ions to form a final NaYF4 phase. The final step involves a continuous, gradual change of the solid phase’s chemical stoichiometry from YF3 toward NaYF4. Unlike previously studied nucleation and growth mechanisms, the stoichiometry of the final solid phase evolves throughout the crystallization process rather than being determined at nucleation. This novel four-step mechanism provides a new perspective into the nucleation and growth of many other crystalline materials given the ubiquity of nonstoichiometric compounds in nature.

Explosive crystallization phenomena in SOI structures

1989 ◽  
Vol 4 (6) ◽  
pp. 1473-1479 ◽  
Author(s):  
H. D. Geiler ◽  
M. Wagner ◽  
E. Glaser ◽  
G. Andrä ◽  
D. Wolff ◽  
...  
Keyword(s):  
Solid Phase ◽  
Amorphous Layer ◽  
Nucleation And Growth ◽  
Time Interval ◽  
Two Phase ◽  
Pulse Technique ◽  
Explosive Crystallization ◽  
Crystalline Nucleus ◽  
Phase Nucleation ◽  
Temperature Time

Using the double pulse technique with two synchronized lasers, we studied the conditions of ignition and evolution of explosive crystallization. The structure of the resulting crystallized layers is analyzed by TEM. Results of calculations are reported describing the development of the two phase fronts: amorphous/molten and molten/crystalline. It is shown that the system takes more than 500 ns to reach the steady state. The experimental results support the model of creating first a melt nucleus in the amorphous layer followed by the formation of the crystalline nucleus in the molten sphere. Competitive solid phase nucleation and growth in the amorphous layer limit the temperature-time interval of melt nucleation. Defined explosively crystallized areas in laterally structured SOI layers are presented.

Solid phase epitaxy versus random nucleation and growth in sub-20nm wide fin field-effect transistors

2007 ◽  
Vol 90 (24) ◽  
pp. 241912 ◽  
Author(s):  
R. Duffy ◽  
M. J. H. Van Dal ◽  
B. J. Pawlak ◽  
M. Kaiser ◽  
R. G. R. Weemaes ◽  
...  
Keyword(s):  
Field Effect ◽  
Field Effect Transistors ◽  
Solid Phase ◽  
Nucleation And Growth ◽  
Solid Phase Epitaxy ◽  
Random Nucleation

An Inverse Fire Modeling Methodology for the Determination of Fire Size, Fire Location, and Soot Deposition in a Compartment

2012 ◽  
Author(s):  
Kristopher J. Overholt ◽  
Ofodike A. Ezekoye
Keyword(s):  
Gas Phase ◽  
Solid Phase ◽  
Fire Modeling ◽  
Fire Intensity ◽  
Intermediate Step ◽  
Fire Size ◽  
Fire Models ◽  
Input Parameters ◽  
In Fire ◽  
Fire Location

Fire models are routinely used in life safety design projects and are being used more often in fire and arson investigations as well as reconstructions of firefighter line-of-duty deaths (LODDs) and injuries. In all of these applications, the fire heat release rate (HRR), location of a fire in a compartment, gas-phase soot concentration, and solid-phase soot accumulation are important parameters that govern the evolution of thermal conditions within the fire compartment. These input parameters can be a large source of uncertainty in fire models, especially in scenarios in which experimental data or detailed information on fire behavior are not available, such as fire investigations and LODD reconstructions. Various methods have been reported in literature to determine the size and location of a fire in a compartment using ceiling-mounted detectors [1–4]. A previous study by the authors developed an inverse fire modeling technique to determine the time-varying HRR of fire in a compartment using measured thermocouple data [5]. The work presented in this paper extends the inverse HRR methodology by developing a technique to determine the location of a fire using wall-mounted heat flux sensors or a surrogate such as degradation characteristics of enclosure boundaries that can be collected during post-fire assessments. Additionally, the presence of soot modifies the radiative transfer field in the hot gas layer (gas phase) as well as radiative heat transfer to surfaces (condensed phase). As a detailed history of compartment conditions becomes less available, there is a need for an inversion methodology to accurately recover governing input parameters such as fire size, fire location, and fire burning properties while maintaining an adequate level of accuracy. As an intermediate step using measured fire test data, we can begin to construct an approach to use rich data to invert for fire intensity, fire location, and fire properties such as the amount of soot produced by the fire.

Using priority growth orientation of crystallite of the Monte Carlo method to study the process of crystal nucleation and growth in liquid phase

2016 ◽  
Vol 30 (05) ◽  
pp. 1650014 ◽  
Author(s):  
Yu Shi ◽  
Manjiao Chen ◽  
Jiankang Huang ◽  
Yufen Gu ◽  
Ding Fan
Keyword(s):  
Monte Carlo ◽  
Liquid Phase ◽  
Crystallite Size ◽  
Solid Fraction ◽  
Solid Phase ◽  
Growth Index ◽  
Nucleation And Growth ◽  
Crystal Nucleation ◽  
Crystallite Growth ◽  
Tracking Method

The technique of “crystallite growth preferred orientation” was presented based on the Monte Carlo (MC) simulations of grain growth, and its factor was used to establish a lattice coordinate tracking method. The nucleation and growth of crystal from the liquid phase throughout the whole simulation were examined. Changes in solid fraction and crystallite size were counted via simulation by lattice tracking. Results showed that the established model could properly reflect crystallite nucleation and growth. The model was also determined capable of accurately estimating the number of solid phase fraction and achieving change in crystallite size by the lattice tracking method. The change in solid fraction and MC step (MCS) satisfied the [Formula: see text] curve during simulation. The crystallite growth index was 0.477, which was relatively close to the theoretical value of 0.5.

Characterization of Nanophase Particle Aggregates by Transmission Electron Microscopy

1997 ◽  
Vol 3 (S2) ◽  
pp. 425-426
Author(s):  
G. Gonzalez ◽  
A. Freites ◽  
C. Rojas
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Condensed Matter ◽  
Nucleation And Growth ◽  
Bulk Materials ◽  
Transmission Electron ◽  
Particle Aggregates ◽  
Nanophase Materials ◽  
New Perspective

In the last few years there has been a growing interest in nanoparticles and nanophase materials. Nanoparticles are considered to be a new state of the condensed matter due to the high relation of atoms in the surface respect to the number of atoms in the volume, and their properties are neither those of atoms nor those of bulk materials.There are many interesting questions still to be answered and processes to be understood, from nucleation and growth processes to propertiesIn the present work we report the results of the fabrication of Mo, MoW and MoNi, particles by d.c. sputtering, under different pressures, from 0.2 torr to 0.8 torr. Their morphology, size distribution, aggregation and structure has been studied by Transmission Electron Microscopy.We analyzed our results contrasting them with those of Chow 1,2 and Birringer 3 and try to explain with a new perspective the formation mechanism of the particles, and the dependence of particle size with Ar pressure.

Real-Time Dynamical Observation of Lattice Induced Nucleation and Growth in Interfacial Solid–Solid Phase Transitions

2016 ◽  
Vol 16 (12) ◽  
pp. 7256-7262 ◽  
Author(s):  
Junjie Li ◽  
Qiang Li ◽  
Zhongchang Wang ◽  
Francis Leonard Deepak
Keyword(s):  
Phase Transitions ◽  
Real Time ◽  
Solid Phase ◽  
Nucleation And Growth

Nucleation and growth of Ge on Si(111) in solid phase epitaxy

2000 ◽  
Vol 369 (1-2) ◽  
pp. 116-120 ◽  
Author(s):  
I Suzumura ◽  
M Okada ◽  
A Muto ◽  
Y Torige ◽  
H Ikeda ◽  
...  
Keyword(s):  
Solid Phase ◽  
Nucleation And Growth ◽  
Solid Phase Epitaxy

Regularities of fluorine leaching from the rocks by organic acids

2020 ◽  
pp. 71-75
Author(s):  
A. V. Savenko ◽  
V. S. Savenko
Keyword(s):  
Aqueous Solution ◽  
Organic Acids ◽  
Acidic Medium ◽  
Solid Phase ◽  
Point Of View ◽  
Distilled Water ◽  
Fluoride Ions ◽  
Positive Correlation ◽  
Ph Range ◽  
Oxalic Acids

Experiments on fluorine leaching from the rocks (alkaline agpaitic granite, dacite, and feldspathic-quartzy aleurite) by 0.005 M solutions of acetic, tartaric, citric, and oxalic acids were carried out. The previously revealed fact of decrease in the fluorine leaching by organic acids as compared with that by distilled water with an increase in acidity of solutions in the pH range from 6.3 to 3.5 is confirmed. According to the leaching ability in relation to distilled water, organic acids are formed a number: oxalic > citric > acetic ≈ tartaric. It is assumed that decrease in pH leads to sorption of fluorides as a result of the replacement of adsorbed hydroxyl ions. From this point of view, less intensive (compared with distilled water) fluorine leaching in acidic medium can be associated with sorption immobilization of fluoride ions in the solid phase. A positive correlation between amounts of leached fluorine and magnesium indicates the existence of a certain common, as well as not established mechanism for transition of these elements from minerals to aqueous solution.

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