부산대학교 도서관

Conventionally, the aragonite polymorph of CaCO3 possesses a ‘needle-like’ morphology. Aragonite crystals with unconventional morphologies, like ‘cauliflower’ and ‘flake’, have been synthesised by combining aqueous solutions of CaCl2 and Na2CO3 under ambient reaction conditions. The unambiguous characterisation of these aragonite polymorphs is based on their characteristic powder X-ray diffraction patterns, Raman and FTIR spectra. The morphologies of these aragonite crystals have been confirmed by scanning electron microscopy. Both ‘cauliflower’ and ‘flake-like’ aragonites are spectroscopically similar to their needle-like congener, except that they are less crystalline in nature and they exhibit minor differences in their FTIR spectra. A plausible mechanism for the formation of these aragonites has been proposed based on the phase transformation behaviour during their syntheses.