Direct formation of nanophase hydroxyapatite on cathodically polarized electrodes

Ultrafine-grained, nanophase coatings of hydroxyapatite were synthesized by electrocrystallization from dilute electrolytes ([Ca]=6.1 x 10-4 M, [phosphate]=3.6 x 10-4 M) at pH values comparable with the biological pH. At these comparatively low supersaturations, hydroxyapatite is shown to be precipitated without the formation of a precursor phase. A description of the sequence of events occurring at the electrode-electrolyte interface is given to explain the mechanism involved in the direct formation of nanophase hydroxyapatite on polarized electrodes.