PNNL

Abstract

Oriented attachment (OA) of nanocrystals is a widely recognized non-classical crystallization mechanism. A fundamental understanding of the forces that govern the dynamics of particle movement, co-alignment, and attachment is needed to control crystal growth by OA, but is currently lacking. Using atomic force microscopy-based dynamic force spectroscopy to directly measure the adhesive force between two rutile TiO2 (001) crystal surfaces as a function of the lattice mismatch angle in water, we show that the forces exhibit 90 periodicity with respect to the lattice mismatch angle, which is generally consistent with the square-lattice arrangement of Ti4+ centers on the rutile TiO2 (001) surface. Molecular dynamic simulations that incorporate relevant molecular details provide a qualitative explanation for the observed orientation-dependence and suggest that hydrogen bonding is predicted to be the main source of the forces at short range.