Journal of Materials Research

Articles

Nanoscale characterization of nautilus shell structure: An example of natural self-assembly

R. Velázquez-Castilloa1 c1, J. Reyes-Gasgaa2, D.I. García-Gutierreza3 and M. Jose-Yacamana3

a1 Texas Materials Institute and Department of Chemical Engineering, University of Texas, Austin, Texas 78712; and Centro de Física Aplicada y Tecnología Avanzada, UNAM, Querétaro 76000, México

a2 Texas Materials Institute and Department of Chemical Engineering, University of Texas, Austin, Texas 78712; and Instituto de Física UNAM, México D.F. 01000, México

a3 Texas Materials Institute and Department of Chemical Engineering, University of Texas, Austin, Texas 78712

Abstract

Structural characterization at the nanometric scale of the Nautilus sp shell was carried out by high-resolution transmission electron microscopy and high-angle annular dark field to understand how the organic and inorganic components are related. The inorganic phase that built the shell is made of calcium carbonate (CaCO3), with the orthorhombic unit cell of the aragonite, in a texturized arrangement in such a way that the c-axis is always perpendicular to the shell surface. The organic material forms films through the plates. We observed for a very first time some aragonite nanocrystals embedded in the organic matrix. This observation supports the hypothesis that the proteins and other organic compounds guide the crystal growth because the organic matrixes are the places where the nanocrystals grow.

(Received November 29 2005)

(Accepted March 09 2006)

(Online publication June 2006)

Key Words:

  • Scanning electron microscopy (SEM);
  • Transmission electron microscopy (TEM);
  • X-ray diffraction (XRD)

Correspondence:

c1 Address all correspondence to this author. e-mail: rodvelazquez@mail.utexas.edu

0Comments