Figure 6.

TEM images and corresponding electron diffraction patterns of calcium carbonate films and fibers precipitated from a reaction solution containing [Ca²⁺] = 10 mM and [PAH] = 1 mg mL^–1 after (a) 8 h, (b) 12 h, (c) 14 h, and (d) 24 h. The film was still amorphous after 8 h (a), whereas after 12 h, it had crystallized to calcite and small protrusions were observed (b). These protrusions developed further after 14 h (c) until fully developed calcite fibers are viewed after 24 h (d).