CaCO3 microparticles were obtained by chemical precipitation from CaCl2 solution using Na2CO3 or (NH4)2CO3 solutions (heterogeneous precipitation) or carbamide (homogeneous precipitation) as precipitation agents. The effects of various experimental conditions, such as the temperature, duration and reagent ratio on the properties of precipitated CaCO3 were experimentally investigated. It was found that the shape of particles and CaCO3 polymorphs depended on the precipitation agent and process temperature; the size of particles—on the reagent ratio, the precipitation agent and the deposition time. Biphasic calcite-vaterite spherical microparticles with the highest polydispersity coefficient (K = 0.98 with an average particle size ln ≈ 3 μm) were obtained using Na2CO3 solution as a precipitation agent under low temperature (20 °C). Calcite rhombohedral crystals (ln ≈ 3 μm) were obtained using carbamide at high temperature (100 °C). Increasing the temperature of Na2CO3 and (NH4)2CO3 solutions (70–100 °C) led to formation of the biphasic aragonite–calcite druses of needle crystals (druses size ≈ 10–30 μm). Increasing the aging time for sediments in the mother liquor up to 1 h did not affect the shape of CaCO3 particles.

中文翻译：

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合成条件对均相和非均相沉淀所得碳酸钙微粒性质的影响

CaCO3 微粒是通过使用 Na2CO3 或 (NH4)2CO3 溶液（非均相沉淀）或尿素（均相沉淀）作为沉淀剂从 CaCl2 溶液中化学沉淀获得的。实验研究了各种实验条件，如温度、持续时间和试剂比例对沉淀CaCO3性质的影响。发现颗粒的形状和 CaCO3 的多晶型取决于沉淀剂和工艺温度；颗粒的大小——与试剂比例、沉淀剂和沉积时间有关。在低温（20°C）下使用Na2CO3溶液作为沉淀剂获得了具有最高多分散系数（K=0.98，平均粒径ln≈3μm）的双相方解石-球霰石球形微粒。方解石菱形晶体 (ln ≈ 3 μm) 是在高温 (100 °C) 下使用尿素获得的。提高 Na2CO3 和 (NH4)2CO3 溶液的温度 (70–100 °C) 导致形成针状晶体的双相文石-方解石晶簇（晶簇尺寸 ≈ 10-30 μm）。将母液中沉淀物的老化时间延长至 1 小时不会影响 CaCO3 颗粒的形状。