Micrmetre-sized HA powders with dense or porous morphologies were prepared by flame spray pyrolysis from a spray solution with citric acid and ethylene glycol. The powders prepared by high temperature flame spray pyrolysis had hexagonaldipyramidal structures of HA regardless of the flow rates of the carrier gas. When the carrier gas flow rate was 20 Lminute−1, the powders prepared had a micrometre size, spherical shape and dense morphology. The mean size of the HA powders with a spherical shape and dense morphology was 1.1 μm. However, the powders prepared at high flow rates of carrier gas above 30 Lminute−1 had sizes of several micrometre and porous morphologies. The composition ratio of calcium and phosphorous components of the HA powders with a spherical shape and dense morphology was 1.69. The morphology of the micrometresized powders with a spherical shape and dense morphology was maintained after post-treatment at a temperature of 900 oC.

Keywords: Hydroxyapatite, Flame spray pyrolysis, Tricalcium phosphate.