Abstract
Hydroxyapatite (HAp) aggregates with c-axis orientation were prepared by a hydrolysis of CaHPO4∙2H2O (DCPD) in NaOH solution at 80-100 ºC. The HAp aggregates were composed of needle-like crystals which were aligned in c-axis direction perpendicular to the flat surface of the plate-like aggregates. The degree of c-axis orientation of the aggregates increased with increasing in heat treatment temperature. Differences of the growth rate of HAp crystals and supplying mechanism of Ca and PO4 from the DCPD caused morphological differences between oriented and random structures of the aggregates.
