Barium titanate based piezoelectric ceramics for bone regeneration

Diogo B. Moniz a, Andreia A. S. Lopes a, Célia Henriques b, Jorge C. Silvab, João P. Borgesa , M. Carmo Lança a, M. Margarida R.A. Lima a

aCENIMAT|I3N, Dep. Ciências dos Materiais, FCT-UNL, 2829-516 Caparica, Portugal

bDepartamento de Física, FCT-UNL, 2829-516 Caparica, Portugal

This work is the preliminary study on sample production for piezoelectric ceramics from barium titanate with calcium substation for bone regeneration. Piezoelectric ceramics as barium titanate have become increasingly attractive for implant coatings, stimulating osteoblast activity thus promoting osseointegration of the implant. Calcium doping will achieve a good compromise between biocompability and piezoelectricity. The powders mixture were produced from analytical reagents and sintered by solid state reaction. The piezoelectric ceramics: BaTiO3 (BT) and Ba1-xCaxTiO3 (BCTx) with x>= 0.3, were characterized by XRD, DTA/TG, DSC, SEM/EDS, to identify the Ca substation and optimize the parameters. The thermal behaviour shows BT endothermic progression associated with weight loss from 813ºC to 939ºC is the continuous transformation of orthorhombic BaCO3 to rhombohedral phase and the subsequent formation of BaTiO3. The main weight loss (11%) occurred from 550ºC to 850ºC. BCT30 shows major weight loss (18%) from 600ºC to 920ºC.Two endothermic peaks from 760ºC to 815ºC corresponding to γ-BaCO3 → β-BaCO3 transformation, 820ºC endothermic peak correspond to the formation of BaTiO3. The following exothermic progression of both BT and BCT30 can be correlated to the crystallization process. The 3 hours milling time was enough to get 3.8 µm medium particle size for both mixtures. XRD for samples sintered at higher temperatures show tetragonal BaTiO3 for BT mixture. In BCT30 the calcium substitution was not done to full extent because there is still CaCO3 phase present and other variants of barium titanate such as Ba0.88Ca0.12TiO3. This can be confirmed in SEM analysis mapping. Despite not being complete the slight peak shift between BT and BCT30 in XRD is due to calcium substitution.  Curie point were obtained by DSC for both BT and BCT30. Calcium presence demands higher sintering temperatures in order to achieve better rate reaction and tetragonality.