Room temperature synthesis of hierarchical SrCO3 Architectures by a surfactant-free aqueous solution route

Novel SrCO3 architectures were prepared by a facile aqueous solution route at room temperature using SrCl2, Na2CrO4, and NaOH as the starting reaction reagents and distilled water as the solvent. The synthesized products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected-area electron diffraction and high-resolution transmission electron microscopy. The SrCO3 architectures are in dandelion-like and flower-like morphologies with diameters of 5-10 mu m and composed of numerous well-aligned single-crystalline nanorods of 20-40 nm in diameter and 1-2 mu m in length. It is found that the morphology of the final products is strongly dependent on the experimental parameters, such as the concentration of aqueous NaOH solution and the reaction temperature. Various controlled synthetic experiments indicate that the growth process of SrCO3 architectures involves the growth of single-crystalline SrCrO4 nanowires, the formation of CO32- ions through the reaction between CO, cas from air and aqueous NaOH solution, and finally the formation of SrCO3 architectures through the reaction between SrCrO4 and CO32- ions controlled by the difference of the solubility product. In addition, a rod to dumbbell to sphere mechanism is proposed for the formation of the SrCO3 architectures.