The key difference between nucleation and particle growth is that nucleation is the formation of a new structure whereas particle growth is the process of increasing the size of a pre-existing structure.
Particle growth has three stages: nucleation, coalescent coagulation, and agglomeration. Nucleation is the first step of particle growth. We often refer to particle growth as “crystal growth”. Hence, nucleation is the first step of crystal formation.
CONTENTS
1. Overview and Key Difference
2. What is Nucleation
3. What is Particle Growth
4. Side by Side Comparison – Nucleation vs Particle Growth in Tabular Form
5. Summary
What is Nucleation?
Nucleation is the initial process of the formation of a crystal. The crystals may form from solutions, liquids or from vapor. Here, a small number of ions, atoms, and molecules get arranged in different patterns, forming a site where additional ions and molecules can get attach with in order to make the crystal larger. For example, nucleation occurs when sugar is supersaturated in water, allowing sugar molecules to stick together and form large crystal structures.
Figure 1: Nucleation
There are two types of nucleation processes: homogeneous process and heterogeneous process. The heterogeneous process is more common than the homogeneous process. However, the homogeneous process becomes more likely when it comes to supersaturation or supercooling.
What is Particle Growth?
Particle growth or crystal growth is the process of increasing the size of a pre-existing crystal structure. It has three stages: nucleation, coalescent coagulation, and agglomeration. Here, nucleation initiates the process, and then additional ions and molecules bind with the newly formed crystal structure to grow it larger. Moreover, crystal growth occurs in all three dimensions.
Figure 2: Crystal Growth in Three Stages
Furthermore, if the molecules or ions fall into different positions rather than the real position in the repeating pattern of the growing crystal, crystal defects may form. Usually, these molecules or ions trap inside the crystal in a fixed position; thus, crystal growth is irreversible.
What is the Difference Between Nucleation and Particle Growth?
Nucleation is the initial process of the formation of a crystal while particle growth or crystal growth is the process of increasing the size of a pre-existing crystal structure. So, this is the key difference between nucleation and particle growth. Moreover, while nucleation is an initiation process, particle growth is the propagation of this initiated process.
Examples for nucleation and particle growth include homogeneous nucleation of diamond in the gas phase and formation of sugar crystals when sugar is supersaturated in water, respectively.
Below infographic summarizes the difference between nucleation and particle growth.
Summary – Nucleation vs Particle Growth
In brief, nucleation is the first step of particle growth. The key difference between nucleation and particle growth is that nucleation is the formation of a new structure whereas particle growth is the process of a pre-existing structure becoming large.
Reference:
1. Huimin Liu, David S. Dandy, in Diamond Chemical Vapor Deposition, 1995
2. “Nucleation.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 3 Feb. 2014, Available here.
Image Courtesy:
1. “Rock-Candy-Closeup” By Evan-Amos – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Process-of-Crystallization-200px” By Krauss – Own work (CC BY-SA 4.0) via Commons Wikimedia