Composition dependence of ferroelectric and piezoelectric properties of epitaxial (1 − x)Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 thin films prepared by pulsed laser deposition

Lead-free (1 − x)Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 (BZT-xBCT) (x = 0.3, 0.4, 0.5, 0.6, 0.7) thin films were deposited on SrRuO3 (SRO)-electroded (0 0 1)-oriented SrTiO3 (STO) single crystal substrates by pulsed laser deposition (PLD). X-ray diffraction and selected area electron diffraction (SAED) patterns verified epitaxial growth for all the thin films. High ferroelectric activities were evidenced by the well-defined polarization-electric field hysteresis loops. Both structural and physical properties of the thin films demonstrated a strong composition dependence and an MPB-like behaviour was found at around x = 0.5, which is in agreement with that of its bulk counterparts. The superior ferroelectric and piezoelectric responses were attained at x = 0.5 with remanent polarization Pr of 17.8 μC/cm2 and piezoelectric coefficient d33 of 100 ± 5 pm/V.