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Spark Plasma Sintering Apparatus Used for the Formation of Strontium Titanate Bicrystals
Published on: February 9, 2017
Surface of strontium titanate
R Herger1, P R Willmott, O Bunk
1Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
Physical Review Letters
|March 16, 2007
Summary
We determined the surface structure of titanium dioxide-terminated strontium titanate (SrTiO3) using surface X-ray diffraction. Heating causes surface reconstructions to disappear, revealing a TiO2-rich surface structure important for thin film growth.
Area of Science:
- Materials Science
- Surface Science
- Solid State Physics
Background:
- Strontium titanate (SrTiO3) is a technologically important perovskite oxide.
- Understanding its surface structure is crucial for thin film growth and device applications.
- Previous studies have suggested various surface terminations and reconstructions.
Purpose of the Study:
- To determine the complete surface structure of TiO2-terminated SrTiO3(001).
- To investigate the surface structure at room temperature and under thin film growth conditions (elevated temperature).
- To elucidate the nature of surface reconstructions and their stability.
Main Methods:
- Surface X-ray diffraction (SXRD) was employed for atomic structure determination.
- Experiments were conducted at room temperature in vacuum and at elevated temperatures.
- Density functional theory (DFT) calculations were used to assess the energetic favorability of proposed structures.
Main Results:
- At room temperature, the surface exhibits a mixture of (1x1) relaxation and (2x1), (2x2) reconstructions.
- The (2x1) and (2x2) reconstructions diminish upon heating, suggesting a transition to a more stable phase.
- The surface structure is best modeled as TiO2-rich, consistent with prior theoretical proposals, with significant atomic displacements extending to three unit cells.
Conclusions:
- The study provides the first complete surface structure determination for TiO2-terminated SrTiO3(001) under relevant conditions.
- Surface reconstructions are dynamic and sensitive to temperature, impacting surface properties.
- Significant subsurface atomic displacements indicate potential for surface ferroelectric phenomena in SrTiO3.
