Effect of TiO<inf>2</inf>-Ag<inf>2</inf>O additives on the formation of calcium phosphate based functionally graded bioceramics

The combined effect of titanium dioxide and silver oxide on the in situ formation of biphasic calcium phosphate ceramics was investigated. Titania (5-20mol%) was mixed with pure hydroxyapatite (HA) or HA containing Ag2O (10-20mol%) and was heated to 900°C for 12h. The sintered samples were found to contain tricalcium phosphate (β-TCP) and other phases along with HA depending upon the amount as well as the type of the additives used as evidenced by X-ray powder diffraction (XRD) and fourier transform infrared (FT-IR) spectroscopic studies. Enhanced TCP formation with reduced impurity phases was observed with TiO2-Ag2O addition. In vitro solubility study in phosphate buffer at physiological conditions shows the resorbable nature of these materials. A functionally graded material (FGM) structure was formed by spreading TiO2-Ag2O mixture on the surface of the HA green compact and heating at 900°C. The FGM shows gradient structure of TCP and HA from the surface to the interior of the pellet in addition to titania and silver phases. Copyright (C) 2000 Elsevier Science Ltd.