Zhang Gan, Morales Juan, García-Ruiz Juan Manuel
Laboratorio de Estudios Cristalográficos, Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Avenida de las Palmeras 4, E-18100 Armilla, Granada, Spain.
J Mater Chem B. 2017 Feb 28;5(8):1658-1663. doi: 10.1039/c6tb02612e. Epub 2017 Feb 8.
The precipitation of barium and strontium carbonate in alkaline silica gels or silica solutions produces nanocrystalline self-assembled composite materials displaying biomimetic shapes and textures. We have crystallized concomitantly in time and space two anhydrous polymorphs of calcium carbonate, under similar conditions at different temperatures. The orthorhombic phase aragonite produces nanocrystalline aggregates exhibiting non-crystallographic morphologies and complex textures characteristic of silica biomorphs. Conversely, the simultaneously forming trigonal phase, calcite, yields rhombohedral crystals that experience fibrous growth and that maintain memory of the point symmetry group of the crystalline structure. Experiments performed at different temperatures (room temperature, 45, 60 and 80 °C) revealed that the higher the temperature the higher the aragonite/calcite precipitation ratio, but the crystallization of calcite was never fully inhibited. We have studied the growth mechanism, the growth texture and the morphogenesis for both cases. We have found that the dramatic difference between the crystallization behaviours of the two mineral phases is due to the difference in the growth mechanism at the nanoscale.
在碱性硅胶或硅溶液中沉淀碳酸钡和碳酸锶会产生呈现仿生形状和纹理的纳米晶自组装复合材料。我们在不同温度的相似条件下，同时在时间和空间上使碳酸钙的两种无水多晶型物结晶。正交晶系的文石相产生纳米晶聚集体，呈现出非晶体形态以及硅基生物形态特有的复杂纹理。相反，同时形成的三方晶系方解石相则产生菱面体晶体，这些晶体经历纤维状生长，并保留晶体结构点对称群的记忆。在不同温度（室温、45、60和80°C）下进行的实验表明，温度越高，文石/方解石的沉淀比例越高，但方解石的结晶从未被完全抑制。我们研究了这两种情况下的生长机制、生长纹理和形态发生。我们发现，两种矿物相结晶行为的显著差异是由于纳米尺度上生长机制的不同。
