Lança, Maria do CarmoLima, Maria MargaridaMoniz, Diogo Duarte Pacheco Botelho2020-01-142020-01-142019-122019http://hdl.handle.net/10362/91167Piezoelectric materials have shown large potential on hard tissue applications due to their ability to stimulate osteogeneses and osseointegration. Barium titanate (BT) is a well-known piezoelectric ceramic. This work reports the consequences of calcium acceptance in BT lattice without compromising the formation of piezoelectric tetragonal phase under physiological conditions. Analytical reagents CaCO3, BaCO3 and TiO2 were used to prepare, via solid state reaction, Ba(1-x)CaxTiO3 (BCT), 0 ≤ x ≤ 0.3 mixtures. Materials were sintered from 1150°C to 1450°C under air and N2 atmospheres. Composites were prepared from Ba(1-x)CaxTiO3 (0 ≤ x ≤ 0.15) and hydroxyapatite (HP) at 10/90 and 20/80 (HP/BCT wt%) proportions. Reagents and produced ceramics were characterized by DTA-TG, granulometry, X-ray diffraction, FTIR, Raman and SEM/EDS. Samples were polarized by corona poling at 110°C, 1 hour, tip potential -15kV and -2kV grid potential for subsequent bioactivity essays. The polarization was analysed by thermally stimulated depolarization currents. Calcium substitution up to 15 mol% deformed the known BaTiO3 lattice without compromising the tetragonal phase stability, maintaining Curie point between 123 °C and 125 °C. All materials tested were non cytotoxic. Corona poling was successfully done to BCT samples. Hydroxyapatite reacts with BCT while sintered at 1350 °C forming different phases, but materials original structures are partially maintained. Early stage bioactivity studies made after both polarized and unpolarized samples were immersed in SBF (simulated body fluid) for 7 days. Results from ICP-AES supported by SEM/EDS point to the materials enhanced ability while polarized to deposit calcium and phosphor ions on its surface.engmaster thesis