Rethinking Classical Crystal Growth Models through Molecular Scale Insights: Consequences of Kink-Limited Kinetics
Rethinking Classical Crystal Growth Models through Molecular Scale Insights: Consequences of Kink-Limited Kinetics
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DOI：
10.1021/cg900543g
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发表时间：
2009-12-01
影响因子：
3.8
通讯作者：
Dove, P. M.
中科院分区：
文献类型：
--
作者：
De Yoreo, J. J.;Zepeda-Ruiz, L. A.;Dove, P. M.
晶体生长的经典阶地-台阶-扭结模型被广泛用于解释生物和地质系统中的矿物形成。一个关键的假设基础上的应用程序的模型是，热波动的步骤是足够快，以产生丰富的扭结网站附着的生长单位。高分辨率原位原子力显微镜（AFM）的研究和动力学蒙特卡罗模拟的步骤边缘的结构和动力学表明，这一物理图像是无效的常见矿物方解石的步骤表现出低扭结密度和弱的步骤边缘波动。因此，杂质与方解石台阶边缘的相互作用不能用基于吉布斯自由能最小化的传统热力学模型来解释。相反，杂质步骤的相互作用遵循不同的机制所确定的动力学连接和分离。当通过生长单元附着到台阶而产生的新扭结超过杂质与新产生的扭结的结合时，台阶前进不受阻碍。这个扭结有限的模型提供了一个合理的解释报告的“动力学不平衡”的微量元素签名。此外，由于扭结密度与晶体溶解度有关，这些发现支持一种基于弱波动的理论来解释许多常见结晶相的生长，这些结晶相在地球化学、生物学和技术环境中具有重要意义。
The classical terrace-ledge-kink model of crystal growth is widely used to interpret mineral formation in biological and geological systems. A key assumption underlying application of the model is that thermal fluctuations of steps are sufficiently rapid to produce an abundance of kink sites for attachment of growth units. High-resolution in situ atomic force microscopy (AFM) studies and kinetic Monte Carlo simulations of step-edge structure and dynamics show this physical picture to be invalid for the common mineral calcite whose steps exhibit low kink density and weak step edge fluctuations. As a consequence, interactions of impurities with calcite step edges cannot be interpreted with traditional thermodynamic models based on minimization of the Gibbs free energy. Instead, impurity-step interactions follow a different mechanism determined by the kinetics of attachment and detachment. Step advance is unimpeded when the creation of new kinks by attachment of growth units to the step outpaces binding of impurities to the newly created kinks. This kink-limited model offers a plausible explanation for reports of "kinetic disequilibrium" of trace element signatures. Moreover, because kink density is tied to crystal solubility, these findings argue for a theory based on weak fluctuations to interpret growth of many common crystalline phases of importance in geochemical, biological, and technological settings.