Surface-Induced Recrystallization of Amorphous Calcium Carbonates to Oriented Calcite Crystals
- PDF / 212,984 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 51 Downloads / 145 Views
K4.10.1
Surface-induced recrystallization of amorphous calcium carbonates to oriented calcite crystals T. Yong-Jin Han*† and Joanna Aizenberg Bell Laboratories, Lucent Technologies 600 Mountain Ave, Murray Hill, NJ 07974
* T.Y.-J. Han, [email protected] † Current Address: Chemistry and Materials Science Directorate, Chemistry and Chemical Engineering Division, Lawrence Livermore National Laboratory, Livermore, CA 94551
Abstract Enigmatic functions of amorphous calcium carbonates (ACC) are explored by inducing the formation and the stabilization of spherulitic ACC particles on self-assembled monolayers (SAM) of hydroxy-terminated alkanethiols on Au surface. We demonstrate that the stabilized ACC particles can be induced to crystallize on command to form oriented calcite crystals by introducing a nucleating surface by a means of a secondary SAM surface with carboxylate functionality.
K4.10.2
Calcium carbonates have been studied extensively for decades due to their abundance in natural surroundings in a variety of shapes and forms.(1-3) As a result, a great understanding in the formation of calcium carbonates have been made, however, the precise mechanism in which organisms utilize calcium carbonates to create exotic and complex shapes and forms has yet to be elucidated. The recent discoveries of amorphous calcium carbonate (ACC) (4-6), one of the least understood forms of calcium carbonate found in a variety of species with enigmatic functions, suggest that it may play a very critical role in determining the final shape and form of calcium carbonates. The biogenic ACC commonly found in nature generally falls under two categories, the stable and the meta-stable forms. The stable forms of ACC, often found associated with water molecules, have been shown to serve as mechanical supports to the living organisms as well as provide possible media for storing calcium and carbonate ions. The meta-stable forms of ACC, also known as transient ACC, are also observed in nature as the precursors to the crystalline forms of calcium carbonates (i.e. calcite and aragonite). Nancollas et al.(7) discovered the presence of synthetic spherulitic ACC, which acted as transient precursor to a crystalline form of calcite crystals as early as 1976 during the crystallization of calcium carbonates in the presence of Mg ions. Since then numerous reports of syntheses of ACC in the meta-stable forms and their subsequent conversion to crystalline calcium carbonates have been observed on various surfaces (8-12) including Langmuir-Blodgett films, and silicon oxide wafers to name a few. However, the versatilities of amorphous calcium carbonates have not been explored fully due to the difficulties in handling the synthetic ACC particles, arising from their high solubility in H2O in the absence of stabilizers (i.e. metal ions, polymers, etc.). Herein, we report a facile synthesis and stabilization of ACC with and without additives, and explore the hidden functions of ACC including its roles as transient precursors to the crystalline forms of calcium ca
Data Loading...
