Transformation of CaCO3 to single crystalline micro/nanowires

Single crystalline CaCO3 micro-nanowires were grown from the solution using poly-vinyl alcohol (PVA) to direct crystal growth and SiO2 nanoparticles acting as seeds for the growth of amorphous CaCO3. The aragonite and calcite micro/nanowire, diameter ranging from 70 to 700 nm, were transformed mostly from rhombohedral calcite and vaterite. The micro/nanowires or spicules grown on glass substrate had lengths ranging from 10 to 50 μm and the growth direction showed no orientational relationship to substrate. Without the use of either SiO2 or PVA, there was no formation of either the amorphous CaCO3 or the micro/nanowires or spicules.