Preferential occupancy of metal ions in the hydroxyapatite solid solutions synthesized by hydrothermal method

The solid solutions in the systems of Ca-Cd HAp [Ca(10-x)Cd(x)HAp (x = 0-10)], Ca-Sr HAp [Ca(10-x)Sr(x)HAp (x = 0-10)] and Ca-Pb HAp [Ca(10-x)Pb(x)HAp (x = 0-10)], were successfully synthesized at 200 degrees C for 12h under hydrothermal conditions. The site of the metal ions in, and ;the solid solutions was analyzed by the Rietveld method. The results of the Rietveld analysis indicated that the metal ions of Ph2+, Sr2+, and Cd2+ all preferentially occupied M (2) sites in the apatite structure. The preferential occupancy of the metal ions in M (2) sites were explained mainly by their ionic radius and electronegativity. (c) 2005 Elsevier Ltd. All rights reserved.