Davis K J, Dove P M, De Yoreo J J
Department of Geological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Science. 2000 Nov 10;290(5494):1134-7. doi: 10.1126/science.290.5494.1134.
Magnesium is a key determinant in CaCO3 mineralization; however, macroscopic observations have failed to provide a clear physical understanding of how magnesium modifies carbonate growth. Atomic force microscopy was used to resolve the mechanism of calcite inhibition by magnesium through molecular-scale determination of the thermodynamic and kinetic controls of magnesium on calcite formation. Comparison of directly measured step velocities to standard impurity models demonstrated that enhanced mineral solubility through magnesium incorporation inhibited calcite growth. Terrace width measurements on calcite growth spirals were consistent with a decrease in effective supersaturation due to magnesium incorporation. Ca(1-x)Mg(x)CO3 solubilities determined from microscopic observations of step dynamics can thus be linked to macroscopic measurements.
镁是碳酸钙矿化的关键决定因素；然而，宏观观察未能提供关于镁如何改变碳酸盐生长的清晰物理理解。原子力显微镜用于通过分子尺度确定镁对方解石形成的热力学和动力学控制来解析镁对方解石的抑制机制。将直接测量的台阶速度与标准杂质模型进行比较表明，通过掺入镁提高矿物溶解度会抑制方解石生长。对方解石生长螺旋的台阶宽度测量结果与由于掺入镁导致有效过饱和度降低相一致。因此，从台阶动力学的微观观察确定的Ca(1-x)Mg(x)CO3溶解度可以与宏观测量联系起来。
