Thermal behaviour of TiOy/HAp nanocomposites

The structural and microstructural characteristics and thermal behaviour of TiO_y/HAp nanocomposite materials used for tissue engineering have been studied by differential and thermal gravimetric analyses (DTA–TGA), X-ray diffraction (XRD) phase analysis and scanning electron microscopy (SEM) methods. Substoichiometric TiO_0.92 and superstoichiometric TiO_1.23 were used in amounts of 10 and 20 wt %, respectively, to reinforce HAp. When the temperature increased as a result of interactions between the matrix and the introduced nanoparticles, titanium monoxide was oxidized to titanium dioxide. Comparing the DTA–TGA and XRD results allowed us to determine the temperature intervals of the beginning of the titanium valence variation and phase transitions occurring in the nanocomposites. The onset temperatures of HAp decomposition and TiO_y oxidation depend on the initial stoichiometry of titanium monoxide and the composition of the reinforcing additive. The TiO_y additives have a stabilizing effect on HAp. The effect of the additive stoichiometry on the interactions between the matrix and nanoparticles in the whole temperature range is shown.