Mesoporous hydroxyapatites prepared in ethanol–water media: Structure and surface properties

Porous calcium hydroxyapatite Ca10(PO4)6(OH)2 (HAp) has been prepared from calcium hydroxide and NH4H2PO4 solutions in alcohol–water media at various temperatures. The resulting powders have been characterized using X-ray diffraction, FT-IR spectroscopy, TG/TD analyses, nitrogen porosimetry, dynamic light scattering, complex impedance method and scanning electron microscopy. The temperature of the reaction and the use of ethanol as the solvent significantly alter the HAp morphology and particle size. The as-precipitated materials are mainly amorphous but they can become highly crystalline after heat-treatment at 800 °C, while still retaining high specific surface area. A correlation between structural and surface properties has been established.