Key Laboratory for Colloid and Interface Chemistry of Education Ministry, School of Chemistry & Chemical Engineering, Shandong University , Jinan 250100, China.
Langmuir. 2015 Mar 3;31(8):2502-10. doi: 10.1021/la503726y. Epub 2015 Feb 20.
Crystalline vaterite is the most thermodynamically unstable polymorph of anhydrous calcium carbonate (CaCO3), and various morphologies can be controlled in the presence of organic additives. Constructing vaterite with minimal defects, determining its distinctive properties, and understanding the formation mechanism behind a biomimetic process are the main challenges in this field. In this paper, a unique single-crystal-like vaterite hexagonal bifrustum with two hexagonal and 12 trapezoidal faces has been fabricated through a catanionic surfactant-assisted mineralization approach for the first time. Compared with the polycrystalline vaterite aggregates, these bifrustums clearly present a doublet for Raman v1 symmetric stretching mode, a low depolarizaiton ratio for carbonate molecular symmetry, and a high structural stability. These indicate a dominant position of hexagonal phase in each crystallite and confirm the Raman v1 doublet characteristics of synthetic and biomineral-based vaterites. Our finding may provide evidence to distinguish vaterite with different structures and shed light on a possible formation mechanism of vaterite single crystals.
水合碳酸的最不稳定晶型为方解石，在有机添加剂存在的情况下，可以控制各种形态的形成。构建具有最小缺陷的文石、确定其独特的性质以及理解仿生过程背后的形成机制是该领域的主要挑战。在本文中，首次通过双离子表面活性剂辅助矿化的方法制备了具有独特单晶状文石六方双锥体的纳米结构，该双锥体由两个六方和 12 个梯形面组成。与多晶文石聚集体相比，这些双锥体在拉曼 v1 对称伸缩模式中表现出明显的双峰，在碳酸盐分子对称性方面具有较低的退偏比，以及具有较高的结构稳定性。这表明每个微晶中都占据主导地位的是六方相，并证实了拉曼 v1 双峰的特征存在于合成和基于生物矿化的文石中。我们的发现可能为区分具有不同结构的文石提供了证据，并为文石单晶的可能形成机制提供了线索。
