Ionic Graphitization of Ultrathin Films of Ionic Compounds
A G Kvashnin1,2, E Y Pashkin2,3, B I Yakobson4
1Skolkovo Institute of Science and Technology (Skoltech), Skolkovo Innovation Center 143026, 3 Nobel Street, Moscow, Russian Federation.
The Journal of Physical Chemistry Letters
|June 24, 2016
Summary
Rocksalt-type structures spontaneously convert to graphitic structures below a critical thickness, driven by reduced surface energy. This conversion can be predicted using fundamental material properties like electronegativity and ionic radius.
Area of Science:
- Materials Science
- Solid-State Physics
- Computational Chemistry
Background:
- Rocksalt-type structures are common in ionic compounds.
- Understanding phase transitions in these materials is crucial for materials design.
- Graphitic structures exhibit unique electronic and mechanical properties.
Purpose of the Study:
- To investigate the graphitization tendency in rocksalt-type structures.
- To determine the critical slab thickness for spontaneous cubic-to-layered conversion.
- To develop a predictive model for this phase transition.
Main Methods:
- Ab initio density functional calculations were employed.
- The study focused on ionic cubic crystal systems.
- An analytical relation was derived using fundamental compound parameters.
Main Results:
- A critical slab thickness was identified for graphitization.
- Surface energy reduction was confirmed as the driving force for conversion.
- An analytical relation was developed to estimate the critical number of layers based on electronegativity and ionic radius.
Conclusions:
- Rocksalt-type structures can transform into graphitic-like structures.
- This transformation is thickness-dependent and driven by surface energy.
- Predictive models using basic material properties can guide the design of new materials.
