Composite materials based on hydroxyapatite (HAP) are of much interest for biology and medicine owing to their bioactivity. The advanced strength properties of HAP can be achieved by its reinforcement with dispersed titanium and titanium oxide particles. This makes it possible to combine biocompatibility with high mechanical strength and fracture toughness.
The structure of initial TiOy nanopowders and nanocomposite materials HAP/TiOy with different stoichiometry (TiO0.92 and TiO1.23) has been studied. The XRD, IR and Raman spectroscopy methods were used to establish the dependence of the shift and relative intensity of bands in the region of 144–151 cm–1 in Raman spectra on the relative content of vacancies and Ti-O bond length. Depending on the stoichiometry of additive during heat treatment, surface groups [Ti(OH)2]2+ and [TiHPO4]2+ are formed on interfaces of matrix and reinforcing additive nanoparticles, partial cationic heterovalent substitution of Ti3+ and Ti4+ for Ca2+ takes place, and new phases, in particular Ti4.5O5 and TiO2, are formed. The stoichiometry of additives affects the initial process of formation of new phase, the phase composition of nanocomposites at different annealing stages, as well as the physical properties of final product.
Of interest are the in situ studies of the physicochemical properties of HAP/TiOy nanocomposites on a synchrotron radiation source, which can provide an insight into the peculiarities of interaction of additives with the matrix and the sequence of phase formation when nanoparticles come in contact.
The reported study was funded by RFBR, project number 20-03-00675.