Kinetics of hydroxyapatite deposition on solid substrates modified by sequential implantation of Ca and P ions

Hydroxyapatite (HA) layers are deposited on three types of solid substrates: stainless steel, silicon and silica glass from supersaturated simulated body fluid (SBF), which simulates conditions typical in human blood plasma. All samples are modified by sequential implantation of Ca and P ions. Thermal treatment in air at 873 K is applied on part of the samples to induce surface oxide layers. The morphology of the grown HA layers investigated by scanning electron microscopy (SEM) is found to be independent on the type of substrates and their surface modification. The elemental composition investigated by energy dispersive X-rays (EDX) shows intensive signals of Ca and P on all ion-implanted, oxidized and untreated samples, as well as signals of Mg, Na, K, Cl, thus, indicating their incorporation in the HA. Fourier transform infrared spectroscopy enables the determination of a structural variation of HA due to a change in the water content of one of the SBF constituents, expressed in high degree of disorder with lower water content.