A computational investigation of stoichiometric and calcium-deficient oxy- and hydroxy-apatites.

Computer modelling techniques have been employed to qualitatively and quantitatively investigate the dehydration of hydroxyapatite to oxyapatite and the defect chemistry of calcium-deficient hydroxyapatite, where a number of vacancy formation reactions are considered. The dehydration of hydroxyapatite into oxyhydroxyapatite is calculated to be endothermic by E = +83.2 kJ mol(-1) in agreement with experiment, where thermal treatment is necessary to drive this process.