Synthesis of Hydroxyapatite from Metal Alkoxides through Sot-Gel Technique

Abstract

Hydroxyapatite was synthesized through the sol-gel technique using Ca(OC2H5)2 and P(OC2H5)3 as starting metal alkoxides. It has been found that the pH of the starting solution is one of the most important factors affecting the formation of hydroxyapatite, The sol-gel reaction rate, the reaction products and the crystalline phases precipitated in heated gels have depended mainly on the pH range of the solution, that is, whether the solution is alkaline (pH≥9), neutral (8≥pH≥6) or acidic (ph≤5). Only hydroxyapatite crystals are precipitated and no additional phases are found when gels derived from the solution of 6 to 8 in pH and more than 60% in water content are calcined above 600°C. The resultant hydroxyapatite crystals obtained have a plate-like structure of about 1000Å in size, resembling closely the hydroxyapatite found in living tissues.