Microstructural Variation of Biogenic Calcite with Intracrystalline Organic Macromolecules

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• 作者：Taiga Okumura ; Michio Suzuki ; Hiromichi Nagasawa ; Toshihiro Kogure
• 刊名：Crystal Growth & Design
• 出版年：2012
• 出版时间：January 1, 2012
• 年：2012
• 卷：12
• 期：1
• 页码：224-230
• 全文大小：419K
• 年卷期：v.12,no.1(January 1, 2012)
• ISSN：1528-7505

文摘

The influence of intracrystalline organic macromolecules on the microstructure and properties of host crystals has been investigated by micro- and macroscopic analyses for several biogenic calcites: prisms in the outer layers of pearl oysters (Pinctada fucata), oysters (Crassostrea nippona), and pen shells (Atrina pectinata); folia in the inner layers of C. nippona and scallops (Patinopecten yessoensis); and coccoliths of Pleurochrysis carterae. Thermogravimetric analysis showed that the three prisms contain more intracrystalline organic matter than the folia and coccolith. Transmission electron microscopy (TEM) revealed that Fresnel contrasts, which probably correspond to the intracrystalline organic macromolecules, are distributed inhomogeneously and partition the calcite crystals into subgrains with small misorientations in the prisms of P. fucata and C. nippona. From peak broadening in powder X-ray diffraction (XRD), we found a large variance of lattice spacing (螖d/d) in the two prisms. On the other hand, intracrystalline macromolecules in the prisms of A. pectinata are distributed rather homogeneously and do not influence the crystal structure, as revealed by diffraction contrast in TEM. XRD of the prisms in A. pectinata indicates significantly smaller 螖d/d than that for the other two prisms. In the folia and coccolith, intracrystalline macromolecules were scarcely observed in TEM, and the estimated 螖d/d is small.