Crystal Nucleation and Growth: Particle Birth and Enlargement Are Different Observations

Define the Phase or Process Boundary

METTLER TOLEDO's nucleation and growth definitions distinguishes birth of crystal nuclei from deposition that increases existing crystal size. A change in one size statistic need not identify which process changed the population.

Review a Hypothetical Comparison

Consider an invented closed observation region where 100 identified crystals each grow from 20 to 24 µm in a fixed-shape model. Count remains 100, while each particle volume rises by (24/20)³=1.728. This is consistent with growth of that tracked population. A different record showing 40 additional persistent small crystal objects requires a population-birth or other count-changing explanation. It cannot be interpreted from the average size alone, and breakage or objects entering the observation region must also be considered.

Keep the Evidence with the Decision

Keep object identity, population counts and size changes as separate evidence. State the observation boundary and whether objects can enter or leave it. Compare dissolved-solute change with the assumed growth inventory if the material balance matters. Avoid using a decreasing mean size as automatic proof of nucleation.

The counts and dimensions are hypothetical. They do not establish real nucleation rates, universal particle shapes or an instrument capable of tracking every nucleus.

Does a population change indicate new crystals, enlargement of existing crystals or both?

This blank worksheet is for your own project. It contains no H M machine trial result.

Customer Questions

Primary References

These references support the technical principles discussed in this guide. The worked examples and review questions are educational.

• METTLER TOLEDO's nucleation and growth definitions
• Reference from hmpharmamachines.com