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Updated: May 7, 2026
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On-Chip Crystallization and Large-Scale Serial Diffraction at Room Temperature
Published on: March 11, 2022
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Illusory spirals and loops in crystal growth.
Alexander G Shtukenberg1, Zina Zhu, Zhihua An
1Molecular Design Institute and Department of Chemistry, New York University, New York, NY 10003.
Summary
Crystal growth theory predicts spirals from dislocations, but this study reveals step bunching creates spirals and loops. L-cystine crystal growth shows bunched steps invert classic dislocation theory predictions.
Area of Science:
- Crystallography
- Surface Science
- Materials Science
Background:
- Classic dislocation theory explains crystal growth via emergent lattice displacements.
- Spiral steps and concentric loops are predicted outcomes of dislocation interactions.
Purpose of the Study:
- To investigate the mechanism of spiral and loop formation in crystal growth.
- To reconcile observed step morphology with existing dislocation-controlled growth theories.
Main Methods:
- In situ atomic force microscopy (AFM) was used to observe step propagation on L-cystine crystals.
- Analysis of growth rates of molecularly thin steps was performed.
- Numerical simulations of crystal growth were conducted.
Main Results:
- Observed spirals and islands on L-cystine crystals exhibited step heights of one lattice displacement.
- Morphological spirals and loops were identified as consequences of smaller step bunching.
- Bunched step morphology inverted theoretical predictions: spirals arose from pairs of dislocations, and loops from single dislocations.
Conclusions:
- The classic theory of dislocation-controlled crystal growth requires revision based on observed step bunching phenomena.
- Anisotropic molecular growth within symmetrical crystals can lead to features that appear to contradict established theories.
- Numerical simulations are crucial for understanding complex crystal growth mechanisms and reconciling theory with observation.
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