Surface modification of nanocrystalline calcium phosphate bioceramic by low energy nitrogen ion implantation

The microwave synthesized hydroxyapatite (HAp-Ca10(PO4)6(OH)2, 35 nm) was implanted with 30 keV nitrogen ion (N+) with fluences of 1×1015, 1×1016 and 1×1017 ions/cm2. The samples were characterized by GIXRD (Glancing Incidence X-ray Diffraction) and atomic force microscopy along with measurement of resistivity, permittivity, ac (alternating current) conductivity, photoluminescence, wettability and in vitro bioactivity. Implantation did not cause any appreciable change in crystallite size and lattice parameters. The ion implanted samples revealed enhanced permittivity, ac conductivity, photoluminescence and average pore size (50%), whereas there was a significant decrease in resistivity, surface roughness, and wettability. The in vitro bioactivity and protein absorption were found to improve on nitrogen ion implantation.