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Synthesis and Characterization of Supramolecular Colloids
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Study of the B1-B2 transition in colloidal clusters
D Bochicchio1, A Videcoq2, R Ferrando1
1Dipartimento di Fisica and CNR-IMEM, Via Dodecaneso 33, Genova I-16146, Italy.
The Journal of Chemical Physics
|January 21, 2014
Summary
This study explores the B1 to B2 phase transition in crystalline colloidal clusters using computational methods. Results show a plane-shifting mechanism with metastable states, influenced by interaction range and screening length.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Computational Chemistry
Background:
- Crystalline colloidal clusters exhibit phase transitions analogous to ionic crystals.
- Understanding these transitions is crucial for designing novel materials.
Purpose of the Study:
- To elucidate the mechanisms of the B1 (NaCl-type) to B2 (CsCl-type) phase transition in colloidal clusters.
- To investigate the role of interaction range and finite-size effects on the transition pathway.
Main Methods:
- Metadynamics simulations to force the B1-B2 transition.
- Nudged elastic band calculations to determine energy barriers.
- Modeling the system with a screened Coulomb potential.
Main Results:
- Identified a transition path involving sequential plane shifts.
- Observed metastable configurations analogous to the Hyde and O'Keeffe mechanism.
- Discovered a surface-initiated, row-by-row mechanism unique to finite-size clusters.
- Found that energy barriers and phase stability strongly depend on screening length.
Conclusions:
- The B1-B2 transition in colloidal clusters proceeds via a distinct plane-shifting mechanism.
- Finite-size effects introduce unique surface mechanisms absent in bulk ionic crystals.
- Long-range interactions significantly enhance the stability of the B1 metastable phase.
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