Figure 4. Crystallization of uncoated ACC particles.

(a) Total weight percent water (Total wt%) and corresponding molecular composition (CaCO₃: xH₂O) from TGA from 25 to 400 °C), electron micrographs with a scale bar, 200 nm after isothermal annealing at 30 °C (b) and 200 °C (c), (d) infrared spectra of ACC particles after a heating procedure involving a ramp (15 °C min⁻¹), followed by isothermal annealing (100 min) and a second ramp (15 °C min⁻¹) all under a 100-ml min⁻¹ N₂ flow).