Coordination polyhedra: A probable basic growth unit in solution for the crystal growth of inorganic nonmetallic nanomaterials?

Learning from the classical crystallization mode and the conventional oriented attachment mode, we demonstrate another understanding of the crystal growth of inorganic nonmetallic nanomaterials in solution from the perspective of coordination polyhedra. A family of β-Ni(OH) ₂ hourglass-like nanostructures is controllably synthesized and chosen to illustrate this understanding, in which the coordination polyhedra of Ni(OH) ₆ ^4- are supposed to serve as the basic growth unit to grow these crystals in solution. According to this "coordination polyhedra growth unit" mode, a probable crystal growth mechanism featuring two-stage oriented attachment is put forth. In addition, with this deliberate mode, a series of anisotropic features as well as interesting structural patterns of the as-prepared β-Ni(OH) ₂ nanocrystals have also been successfully explained. The nanocrystal growth mechanism proposed in this paper may be general; for example, it might reflect the actual circumstances of crystallization of certain inorganic nonmetallic nanocrystals in solution.