中文摘要：

采用原位直接成像法（In situ atomic force microscopy）研究层状硅酸盐含钾矿物黑云母与低分子量有机酸的界面反应。结果表明,在近分子尺度下,黑云母具有典型的层状结构单元,高度约1 nm。天然黑云母片（001）面并非完全解理,其上既有台阶也有残片、碎片和蚀坑。在pH 6.0的柠檬酸盐溶液作用下,0-45 min内,黑云母（001）面上的台阶以0.01μm2min-1的恒定速率溶解,之后溶解速率降低;表面原有蚀坑边缘变模糊,但面积没有明显变化,同时（001）面上也没有新的蚀坑形成。通入pH 4.0柠檬酸盐溶液,经过89 min的反应,大量无规则形状的蚀坑产生并散乱分布于（001）面上,深度以0.7-1.1 nm为主;另外表面上还有诸多微型蚀坑正在形成并逐渐扩展为较大的蚀坑。结合水-矿物界面反应理论可知,弱酸环境条件下,黑云母溶解从表面的缺陷/扭折位点开始,以单层（TOT）溶解为主,沿着[hk0]方向发展并伴随着层间K和晶格中Si、Al、Mg和Fe的释放。本研究结果表明原位直接成像技术能够弥补常温常压条件下宏观研究技术的不足、通过可视化来实时表征层状硅酸盐矿物-水溶液的界面反应过程。另外,原子力显微镜技术对其他领域的界面研究同样具有较高的借鉴意义。

英文摘要：

The in-situ direct imaging method（ or in-situ atomic force microscopy） was used in studying interfacial reaction of biotite with low molecular weight organic acid. The low molecular weight organic acid used in the research is citric acid,which is one of the most important components of root exudate and,therefore,ubiquitous in the soil-plant system. Biotite,belonging in the mica group,is a kind of phyllosilicate mineral,which contains potassium（ K）,magnesium（ Mg） and iron（ Fe）,essential for the crop growth. In order to observe how biotite is dissolved and changed in morphology changes in soil,an experiment was carried out with two pH treatments（ 4. 0 and 6. 0）. Observation on the near-molecular scale reveals that biotite is a typical unit of layered structure,about 1 nm in height. The surface of biotite（ 001） is not smooth but full of terraces,debris and etches pits,which would disturb the dissolution process of biotite. In citric acid solution,6. 0 in pH,the terraces on the biotite（ 001） surface were dissolved at a constant rate of 0. 01 μm2min- 1within the first 45 min,and afterward,at a declining rate,and the original etch pits on the surface did not change much in area,but had edges blurred. Meanwhile,no new etch pits formed on the（ 001） surface. When treated with citric acid solution4. 0 in pH for 89 min,the biotite had a large number of irregular shaped tiny etch pits formed,which were randomly distributed on the（ 001） surface and mostly,about 0. 7 ～ 1. 1 nm in depth,and in addition quite a number of mini pits were forming and expanding into large ones. The original terrace on（ 001） surface also did not dissolve notably in area compared to that of the beginning situation. It is learnt from understanding of the theory of interactions on water-mineral interface that in weak acid environment,dissolution of biotite starts from defect /kink sites on the surface,one layer by one layer,and develops along the [hk0]direction,while releasing K from between layers and Si,Al,Mg