Study of synthetic hydroxyapatite by the method of high-resolution transmission electron microscopy: Morphology and growth direction

Hydroxyapatite crystals grown from aqueous solutions have been studied by t he methods of high-resolution electron microscopy and transmission electron diffraction. Processing of the experimental electron micrographs with the use of the Digital Micrograph program and the study of the corresponding Fo urier transforms showed that the submicron microcrystals grow mainly along the [0001] direction. The (0001) and the (01 (1) over bar 0) planes are per pendicular and parallel to the long edge of the crystals, respectively. The good accord between the experimental electron-microscopy images and the el ectron microscopy images calculated by the EMS program was attained only fo r crystals with the thicknesses ranging from one to five lattice periods. T his allows us to state that hydroxyapatite grows from aqueous solutions in the form of very thin (with the thickness of the order of several lattice p arameters) platelike crystals. (C) 2000 MAIK "Nauka/Interperiodica".