Preparation of CaCO₃ and CaO Nanoparticles via Solid-State Conversion of Calcium Oleate Precursor

Calcium carbonate (CaCO₃) and monodisperse calcium oxide nanoparticles (CaO NPs) are prepared by the calcination of solid-state calcium oleate precursor in air condition. The effect of calcination temperature on the synthesis of CaCO₃ and CaO NPs is examined. The polymorphism is confirmed by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The sample morphologies including their size and size distribution are investigated by field emission scanning electron microscopy (FESEM). Calcination of calcium oleate between 400 and 550 °C results in CaCO₃ NPs with mean sizes from 82 to 98 nm, whereas monodisperse spherical CaO NPs are obtained at 650 °C and an average size is estimated to be 40 nm. Beyond 650 °C, the size of CaO NPs increases with broad size distribution. The results of this study provide a novel approach to monodisperse CaCO₃ and CaO NPs that can be applied in a variety of fundamental and industrial fields.