水热条件下不同形貌和晶相碳酸钙的形成和转化

Formation and Transformation of CaCO_3 with Various Morphologies and Crystalline Phase under Hydrothermal Conditions

利用碳酸氢钙水热分解制备了具有不同形貌和晶相的碳酸钙。在水热情况下,得到了多种形貌的方解石和霰石碳酸钙,研究了碳酸氢钙浓度、添加剂氯化镁浓度、反应时间和温度等对碳酸钙形貌和晶相的影响。以X射线衍射(XRD)和扫描电镜(SEM)对制备的碳酸钙进行了表征。研究发现,水热条件对碳酸钙形貌和晶相的形成以及演化过程有重要影响。水热条件下发现了稳定的碳酸钙晶相向亚稳定相转化的反常相变,对相关的形成及转化机理进行了相应的阐述。

Calcium carbonate （CaCO3 ） crystals with various shapes were fabricated by hydrothermal decomposition of Ca （HCO3 ）2. Under hydrothermal conditions, calcite and aragonite with different morphologies were obtained and the effect of concentration of Ca （ HCO3 ） 2, additive of MgCl2, reaction time and temperature on the morphology and structure of CaCO3 were investigated. The as-prepared products were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. Operating factors were crucial for the control of morphologies and structures of CaCO3. An unusual phase transformation of the CaCO3 was observed under our hydrothermal conditions and the possible formation mechanism of the CaCO3 was accordingly proposed.