A shield, a dance and a growing crystal

Study suggests a mechanism for controlling crystallisation. 

Local fluctuations allow molecules to leave the solvation shell and integrate into the crystal surface.

Meenesh Singh

Efforts to improve a range of crystalline materials, from self-healing biomaterials to solar panels, have been hampered by the fact that scientists don’t fully understand how crystals grow or how to efficiently manufacture them.

Now researchers from the University of Illinois at Chicago, US, say they have unlocked part of the mystery.

Using computer-based simulations to analyse how atoms and molecules move in a solution, Meenesh Singh and colleagues identified a general mechanism governing crystal growth they say scientists can manipulate when developing new materials.

Specifically, they report in the journal Proceedings of the National Academy of Sciences, when crystal-forming molecules are surrounded by a solvent, such as water, the solvent molecules form a shield they call a solvation shell.

"Under the right conditions, the shield dances around and allows molecules to break free and integrate into the crystal surface,” says Singh.

“The fluctuations in the solvation shell are key molecular events that explain how crystals form: knowledge of this mechanism has been missing since the inception of crystallisation research."

The study found that temperature, solvent type and the number of solvent molecules all affect the shell's fluctuation.

Explore #crystals
  1. https://www.pnas.org/content/early/2019/11/05/1910691116
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