School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, United Kingdom.
Nanoscale. 2011 Jan;3(1):265-71. doi: 10.1039/c0nr00589d. Epub 2010 Nov 10.
The kinetics and mechanisms of nanoparticulate amorphous calcium carbonate (ACC) crystallization to calcite, via vaterite, were studied at a range of environmentally relevant temperatures (7.5-25 °C) using synchrotron-based in situ time-resolved Energy Dispersive X-ray Diffraction (ED-XRD) in conjunction with high-resolution electron microscopy, ex situ X-ray diffraction and infrared spectroscopy. The crystallization process occurs in two stages; firstly, the particles of ACC rapidly dehydrate and crystallize to form individual particles of vaterite; secondly, the vaterite transforms to calcite via a dissolution and reprecipitation mechanism with the reaction rate controlled by the surface area of calcite. The second stage of the reaction is approximately 10 times slower than the first. Activation energies of calcite nucleation and crystallization are 73±10 and 66±2 kJ mol(-1), respectively. A model to calculate the degree of calcite crystallization from ACC at environmentally relevant temperatures (7.5-40 °C) is also presented.
采用基于同步加速器的原位时间分辨能量色散 X 射线衍射（ED-XRD）结合高分辨率电子显微镜、非原位 X 射线衍射和红外光谱，研究了纳米无定形碳酸钙（ACC）通过球霰石向方解石的动力学和机理，研究范围为一系列环境相关温度（7.5-25°C）。结晶过程分两个阶段进行；首先，ACC 颗粒迅速脱水并结晶形成单个球霰石颗粒；其次，通过溶解和再沉淀机制将球霰石转化为方解石，反应速率受方解石表面积控制。反应的第二阶段比第一阶段慢约 10 倍。方解石成核和结晶的活化能分别为 73±10 和 66±2 kJ mol(-1)。还提出了一个计算环境相关温度（7.5-40°C）下 ACC 中方解石结晶度的模型。
