Formation of calcium phosphate nanoparticles in reverse microemulsions

Nanosized calcium phosphate powder had been synthesized via an inverse microemulsion processing route, which used cyclohexane as the oil phases, octaethylene glycol monododecyl ether (C12EO8) as surfactant phase, and an aqueous Ca(NO3)2 and (NH4)2HPO4 solution as the water phase. A wide variety of morphologies were encountered in synthesis which produced nanosphere (25-40 nm in diameter), sheet-like (3-16 nm in width and 50-300 nm in length), rod-like (10-17 nm in diameter and 24-50 nm in length) and needle-like (4-8 nm in diameter and 80-100 nm in length). The great structural diversity was resulted from the different value of the molar ratio of water to surfactant, W0. Particles were visualized by transmission electron microscopy (TEM) and the identities of powder confirmed by FT-IR and X-ray diffraction (XRD).