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Piezoelectric ceramics for bone regeneration
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Piezoelectric 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.