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Coexisting surface phases and coherent one-dimensional interfaces on BaTiO3(001)
Erie H Morales1, John Mark P Martirez, Wissam A Saidi
1Department of Materials Science and Engineering, University of Pennsylvania , Philadelphia, Pennsylvania 19104-6202, United States.
ACS Nano
|April 19, 2014
Summary
We discovered two coexisting surface reconstructions, c(2 × 2) and c(4 × 4), on BaTiO3(001). TiO diffusion forms the c(2 × 2) phase, while TiO clustering forms the stable c(4 × 4) phase, creating unique interfaces.
Area of Science:
- Surface Science and Materials Chemistry
- Atomic and Nanoscale Surface Characterization
- Thin Film Growth and Epitaxy
Background:
- Understanding the coexistence of surface reconstructions is crucial for controlling material properties.
- Surface reconstructions significantly influence kinetic and thermodynamic processes in materials.
- Barium titanate (BaTiO3) is a key material in ferroelectric and dielectric applications.
Purpose of the Study:
- To identify and characterize coexisting surface reconstructions on BaTiO3(001) at the atomic level.
- To elucidate the formation mechanisms and thermodynamic stability of different surface phases.
- To explain the origin of coherent interfaces between coexisting reconstructions.
Main Methods:
- Atomically resolved Scanning Tunneling Microscopy (STM) for surface imaging.
- First-principles thermodynamic calculations to determine surface composition and stability.
- Analysis of diffusion and clustering of TiO units to explain phase formation.
Main Results:
- Identified the coexistence of c(2 × 2) and c(4 × 4) surface reconstructions on BaTiO3(001).
- Determined that TiO adunits and clusters constitute the observed surface phases.
- Showed that TiO diffusion leads to the kinetically accessible c(2 × 2) phase, while TiO clustering yields the stable c(4 × 4) phase.
Conclusions:
- The formation of distinct surface reconstructions is governed by TiO diffusion and clustering dynamics.
- The direction of TiO diffusion dictates the formation of 1D coherent interfaces between c(2 × 2) and c(4 × 4) domains.
- Proposed atomic models for the c(2 × 2), c(4 × 4) reconstructions, and their 1D interfaces.
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