Polarized light images of magnesium carbonate microhemispheres synthesized under temperature oscillation conditions.

(A) Microhemispheres synthesized from a mixture of 240 mM MgAc₂, pH 6.5 with 400 mM NaHCO₃ (V/V, 1∶1) at T setting of 55°C for 6 h. (B) Microhemispheres synthesized from a mixture of 240 mM MgCl₂ with 500 mM NaHCO₃ (V/V, 1∶1) at T setting of 55°C for 6 h. (C) and (D) Fragments of microhemispheres synthesized from a mixture same as that of (B) at T setting of 55°C for 14 h and T setting of 50°C for 14 h, respectively.