Nano-sized, spherically shape and monodispersed hydroxyapatite (HA) powders were prepared by a high temperature flame spray pyrolysis process. The powders prepared from the aqueous spray solution without ethyl alcohol had a bimodal size distribution with nanometre and submicrometre sizes. Nano-sized and monodisperse HA powders were prepared when the volume ratio (ethyl alcohol/distilled water, V/V) in the mixed solvent was 1 : 2. Nano-sized HA powders were formed from the evaporated vapors by a chemical vapor deposition (CVD) process. The mean size of the HA powders measured from TEM images was 37 nm. The composition ratio of calcium and phosphorous components of the nano-sized HA powders was 1.63. The nano-sized powders obtained from the spray solution with a volume ratio of ethyl alcohol to distilled water at 1 : 2 had a phase pure hexagonal-dipyramidal structure of HA.

Keywords: Hydroxyapatite, Flame spray pyrolysis, Nano powder, Chemical vapor deposition.