Crystal orientation regulation in ostrich eggshells

The structure and crystallographic orientation of different layers (the cone layer, palisade layer and the crystal layer) in ostrich eggshells were studied by scanning electron microscope (SEM). X-ray diffraction (XRD) and transmission electron microscope (TEM) with selected area electron diffraction (SAED). It is found that the degree of 0 0 1 preferred orientation enhanced from inner to outer ostrich eggshells. A crystallographic orientation regulation was observed for the first time. The adjacent 1-5 calcite crystals with the same three-dimensional orientation are proposed to form a crystalline cluster with the size of several microns. The a-axes in the neighboring clusters orient from several degrees to tens of degrees. (C) 2001 Elsevier Science B.V. All rights reserved.