Proto-Calcite and Proto-Vaterite in Amorphous Calcium Carbonates
Proto-Calcite and Proto-Vaterite in Amorphous Calcium Carbonates
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DOI：
10.1002/anie.201003220
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发表时间：
2010-01-01
影响因子：
16.6
通讯作者：
Hedin, Niklas
中科院分区：
文献类型：
--
作者：
Gebauer, Denis;Gunawidjaja, Philips N.;Hedin, Niklas
碳酸钙的结晶通常是通过亚稳定相依次进行的。无定形碳酸钙(ACC)通常在体外和体内最初形成，是主要的无水晶型(方解石、文石和球铁矿)的前体。[1-13]碳酸钙结晶的新图景正在出现，它涉及到团簇向ACC和最终到晶型的转变。[14，15]这种逐步形成的方式对于理解生物矿化[16]和结晶具有重要意义。含有添加剂的ACCs在原子长度尺度上显示出与晶型有关的有序性；[1-3]ACC是在没有添加剂的高过饱和度水平下合成的，[17-20]，另一方面，没有显示出明显的短程有序性。我们分别用PC-ACC(原方解石ACC)和PV-ACC(原方解石ACC)对ACCI和ACCII的鉴别进行了合理化。通过过量乙醇的失稳，在不同pH值的碳酸钙介稳溶液中沉淀出这些ACCs。
Crystallization of calcium carbonate, typically, progresses sequentially via metastable phases. Amorphous CaCO3 (ACC) generally forms initially, both invitro and invivo, and is the precursor of the predominant anhydrous polymorphs (calcite, aragonite, and vaterite).[1–13] A new picture of the crystallization of calcium carbonate is emerging, which involves transformations of clusters to ACC and eventually to crystalline polymorphs.[14, 15] This stepwise manner has implications for the understanding of biomineralization [16] and of crystallization. ACCs that contain additives display order over atomic length scales that are related to crystalline polymorphs;[1–3] ACC synthesized at high supersaturation levels without additives,[17–20] on the other hand, show no distinct short-range order.[21, 22] Herein, we analyze proto-crystalline features of two amorphous intermediates, ACCI and ACCII,[15] and discuss their relevance for crystallization of CaCO3. We rationalize the identification of ACCI with pc-ACC (proto-calcite ACC) and ACCII with pv-ACC (proto-vaterite ACC), respectively. These ACCs were precipitated from metastable solutions of calcium carbonate at different pH values by destabilization in excess ethanol.