冰冻-解冻法制备CaCO_3纳米粉体

Preparation of Nanometer Scale Calcium Carbonate by Freeze-Thawing Method

用无水碳酸钠和无水氯化钙为原料,以Ca^2＋-H2O-CO^2-3反应系统生成碳酸钙沉淀,按碳酸钙与水以质量比为1∶10加入蒸馏水,置冰箱中（-20℃）静态冷冻12h,取出在室温下解冻,过滤后得到样品。TEM和XRD测试结果表明：粒子基本呈球形,晶体粒径约为40～70 nm,所得产物为方解石型CaCO3。同时提出了“冰切割”机理,并对其形成进行了初步探讨,得出了冰冻-解冻制备纳米碳酸钙的新方法。

Nanometer scale powders calcium carbonate was prepared with sodium carbonate and calcium chloride. The composites of calcium carbonate was synthesized by co-precipitation method in Ca^2＋ -H2O^- CO^2-3 reaction system. Added distilled water to precipitation at the mass volume ratio 1：10 of CaCO3/H2O. The compound was cooled to -20℃ and frozen for 12h. Frozen calcium carbonate was thawed in room temperature. The size and structure of calcium carbonate were analyzed by means of TEM and XRD, the results showed that the nanometer scale powders calcium carbonate was calcite crystal group in structure and spherical in shape with the size of average particles ranging from 40 to 70 nanometer. ＂ Crystal Divided by Ice＂ was put forward and the synthesis mechanisms of nanometer scale powders calcium carbonate were also discussed in details. A new method that nanometer scale powders calcium carbonate was prepared by a freeze- thawing is educed.