Formation mechanism of novel two-dimensional single crystalline dendritic copper plates in an aqueous environment

This paper reports on the creation of a unique form of single crystalline two-dimensional (2-D) copper microdendritic plates and proposes a new crystal growth mechanism in an aqueous environment. The crystals are formed via reduction of CuSO₄ with starch in aqueous solution. The 2-D crystals are typically ∼300 nm thick and ∼50 μm wide, and consist of rhombic petals of (1 1 1) planar orientation. The plates are found to nucleate at the centre in polyhedral shapes and grow outwards along zigzag growth paths along the 〈112̄〉 directions. Formation of such a crystal morphology is attributed to three different growth controlling criteria. The formation of polyhedral crystalline nuclei is controlled by the Gibbs-Wulff theorem, driven by the need to minimize the total surface energy for nucleation; growth of the crystal to form a 2-D rosette morphology is controlled by the planar expansion kinetics of low surface energy crystallographic planes; the zigzag dendritic growth pattern is dictated by the Cu²⁺ concentration gradient at the crystal growth fronts in the solution.