Electrocrystallization of Calcium Phosphates

The interest in electrocrystallization of calcium phosphates (CaP) in general. and of hydroxyapatite (HAp) specifically, results from the promising industrial benefits, unique microstructures, and properties of the deposits produced by this process, and the possible similarity to bone mineralization in vivo. In this paper, out work on electrocrystallization of HAp and octacalcium phosphate (OCP) on CP-Ti and Ti-6Al-4V alloy, in solution containing calcium nitrate and ammonium dihydrogen phosphate, is briefly reviewed. The early stages of nucleation and growth are characterized in real time by means such as electrochemical quartz crystal microbalance (EQCM) and electrochemical atomic force microscope (EC-AFM). The change in growth mode and the role of precursors to HAp are explained. The role of charge transfer and local increase in pH is discussed.