Preparation and characterization of hollow hydroxyapatite microspheres by the centrifugal spray drying method

► Hollow hydroxyapatite microspheres were synthesized by the centrifugal spray drying method. ► The ammonium bicarbonate was added as the pore forming agent. ► The microspheres had fine spherical morphology with a hollow internal structure. ► Prepared hollow hydroxyapatite microspheres show a high specific surface area and porosity.