Structural analyses of carbonate-containing apatite samples related to mineralized tissues

Crystallographic and structural aspects of two carbonate-containing (one with and another without Zn ions) and a pure hydroxyapatite sample were investigated by high resolution electron microscopy. For five different zone axes and for the three samples a good correspondence was always found between simulated lattice images and observed micrographies. Numerous structural defects were detected in the carbonate-containing apatites, whereas none were found in the similarly prepared pure hydroxyapatite. The incorporation of Zn ions in the crystal lattice of the carbonate-containing apatite reduces the number of defects.