We report an experimental investigation of equilibrium shapes of epitaxial Au nanocrystals (NCs) supported on rutile TiO2 (110) and the role of interfacial triple line energy (TLE). The study was enabled by aberration corrected electron microscopy; the significantly improved image resolution allows us to determine the shape of NCs in the cross-sectional geometry with accuracy of a single atomic layer. By analyzing the shapes of NCs of 4-11 nm Au NCs, we found that the shape was not self-similar between the largest and smallest size. We attribute this loss in self-similarity to the enhanced effect of interfacial TLE of smaller NCs and modified the Wulff-Kaishew theorem of unstrained NCs to include the effect of TLE on NC shape. By fitting the data from experimentally observed shapes, we measured the interfacial TLE to be 0.28±0.08eV/(4.53±1.27× 10⊃-10 J/m) and interfacial energy to be 0.61±0.06J/ m2 (assuming γ TiO2 (110) =0.33J/ m2 and γAu(111) =1.283J/ m2) for NCs with the epitaxial relationship Au (111) [1̄ 10] TiO2 ( 110) . The effects of surface energy and strain relaxation on NC shape are discussed.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Nov 10 2010|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics