Energy Calculations Predict Nanoparticle Attachment Orientations and Asymmetric Crystal Formation

Novel nanomaterials properties can stem from unusual morphologies that arise via oriented attachment (OA)-based crystal growth. However, the currently understood thermodynamic driving force of surface energy reduction for OA cannot predict experimental observation of attachment on relatively low energy surfaces in some crystals or sequential OA events that result in nanocrystals with morphology not predicted by symmetry. In this work, using molecular energetic calculations, we show that orientation-specific long-range interatomic interactions, in addition to surface energy reduction, predict morphology development and explain how OA produces crystals with lower symmetry than the initial material. Results also show that Coulombic interactions, rather than van der Waals interactions, control OA of ionic nanocrystals. Our computational approach and results can guide the selection or design of nanomaterials to achieve desired morphology as well as new physical and chemical properties.