Effect of thermal annealing on crystal structures and electrical properties in BaTiO₃ ceramics

Mechanical damage and stress caused by polishing and cutting of ferroelectric materials could deteriorate their dielectric, ferroelectric, and piezoelectric properties. BaTiO₃ piezoelectric ceramics were polished and cut, and thermally annealed at 600, 800, 1000, and 1200 °C for recovery. The electrical measurements revealed a reduction in the coercive field, elimination of imprint behavior, and an increase in saturation polarization in the thermally annealed ceramics. Furthermore, the electromechanical properties measured by the resonance method, prior to thermal annealing were d₃₃ = 184 pC/N, k₃₃ = 0.36, and s₃₃^E = 10.9 × 10⁻¹² m²/N, while the values after 1200 °C-4 h thermal annealing were d₃₃ = 287 pC/N, k₃₃ = 0.54, and s₃₃^E = 12.1 × 10⁻¹² m²/N. The in situ crystal structure evaluation and Williamson-Hall analysis suggested the decrement of microstrain from 6.38 × 10⁻⁴ to 5.20 × 10⁻⁴, indicating the retrieval of the residual stress imposed. The enhancement of piezoelectricity by 56% was ascribed to the effective annealing out of the surface mechanical damaged layers.