Directed nucleation and growth by balancing local supersaturation and substrate/nucleus lattice mismatch

Abstract

Controlling nucleation and growth is crucial in biological and artificial mineralization and self-assembly processes. The nucleation barrier is determined by the interfaces and local supersaturation. Although chemically tailored substrates and lattice mismatches are routinely used to modify various forms of energy contributions as resulted from the substrate/nucleus interface and thereby steer controlled heterogeneous nucleation, strategies to combine this with control over local supersaturations have remained virtually unexplored. Here we demonstrate simultaneous control over both parameters to direct the positioning and growth direction of mineralizing compounds on preselected polymorphic substrates. We exploit the polymorphic nature of calcium carbonate (CaCO3) to locally manipulate the carbonate concentration and lattice mismatch between the nucleus and substrate, such that barium carbonate (BaCO3) and strontium carbonate (SrCO3) nucleate only on specific CaCO3 polymorphs. Based on this approach we position different materials and shapes on predetermined CaCO3 polymorphs in sequential steps, and guide the growth direction using locally created supersaturations. These results shed light on nature’s remarkable mineralization capabilities and outline new fabrication strategies for advanced materials, such as ceramics, photonic structures and semiconductors.