Enhancement of switching/un-switching leakage current and ferroelectric properties appraised by PUND method of (Ba1-xCax)TiO3 lead free piezoelectric near MPB

摘要

Lead free perovskite (Ba1-xCax)TiO3 (BCT) (0 < x <= 0.4) ceramics were successfully prepared by Sol gel technique in lower thermal processing conditions than the solid solution method. The samples were calcined at 1000 degrees C/and they were sintered at 1200 degrees C. The structure, dielectric, leakage current and ferro-piezoelectric properties of perovskite (Ba1-xCax)TiO3 (0 < x < 0.4) were investigated. In Ca-doping range 0 < x < 0.3, pure single phase of BCT has been detected. Secondary phase of CaTiO3 has been detected for x = 0.4. The addition of Ca2+ has a negligible effect on the Curie temperature but it inhibits the grain dwindle. High permittivity and low dielectric loss values were achieved in the sample (Ba0.8Ca0.2)TiO3 due to Morphotropic Phase Boundary (MPB) coexistence. Anomalous switching leakage peak (similar to 2 kV/cm) was observed due to the domain switching. The (Ba0.8Ca0.2)TiO3 exhibits low leakage even in the absence of the electric field (J(off) = 1.5368e(-13) A/cm(2)), due to the enhancement of the microstructure properties. The Ferroelectric properties were estimated by P-E loop and Positive Up Negative Down (PUND) methods and the results are shown the remnant polarization estimated by P-E loop is almost back to leakage current contribution. Piezoelectric properties were enhanced in (Ba0.8Ca0.2)TiO3 (d(33)* = 498 pm/v) due to BT-CT phases coexistence.