Novel Lead-free Biocompatible Piezoelectric Hydroxyapatite (HA) – BCZT (ba0.85ca0.15zr0.1ti0.9o3) Nanocrystal Composites for Bone Regeneration

BCZT (Ba0.85Ca0.15Zr0.1Ti0.9O3 ) is a recent class of lead-free ferroelectric material associated with high piezoelectric coefficient, making it suitable to inspire hydroxyapatite (HA)-BCZT ceramics for bone materials. Nano-crystalline hydroxyapatite (HA) synthesized using the hydrothermal route was characterized via FT-IR, Raman spectroscopy, X-ray powder diffraction (XRD), and Scanning Electron Microscopy (SEM). We also rationalized its formation as a function of operating conditions such as dwell time and temperature in this route. The nanocrystalline BCZT powder was synthesized via a sol-gel technique and its structural and morphological characterization were carried out using Raman Spectroscopy, XRD and Transmission Electron Microscopy (TEM). These investigations facilitated the optimization of HA-BCZT compositions and their electrical poling conditions to achieve enhanced piezoelectric effect. The composites (HA-BCZT) sintered at 1350 degrees C exhibited promising piezoelectric properties. We report the enhanced piezoelectric coefficient (d(33)) of 7 +/- 1 pC/N for 50% HA-BCZT which is significant as compared to that reported in the literature for similar to 98% BT (barium titanate) - HA composites. We highlight the role of Simulated Body Fluid (SBF) on the intriguing phase-change of Tricalcium Phosphate (TCP) obtained at this sintering temperature, to hydroxyapatite for its essential contribution to promote bone growth. We theoretically support the confirmed in vitro biocompatibility of these composites.