Sonosynthesis of Vaterite-Type Calcium Carbonate

Metastable nanoparticles of vaterite were formed using a simple ultrasound technique. The effects of ultrasound amplitude and duration, as well as solution concentration, were investigated. The produced particles were characterized using standard X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning and transmission electron microscopies (SEM and TEM, respectively). As expected, the ultrasound synthesis process caused the particle size to be smaller than with conventional (magnetic bar) stirring, and allowed for the reaction time to be shortened as the crystallization rate was increased. As shown by XRD, FTIR, and SEM, the ultrasound process also led to the formation of pure vaterite, though the presence of calcite occurred as the ultrasound power was reduced and the pulse time increased. For both conventional and ultrasound techniques, the particle size was reduced with an increase in starting solution concentration. Using this technique allows for reproducible, tailored calcium carbonate particles for controlled drug delivery, as well as for use in composites for soft tissue repair; in particular, when used as the filler during electrospinning and melt electrospinning.