The (1-x)Ba0.85Ca0.15Zr0.08Ti0.92 -xGe lead-free ceramics with high piezoelectric activity and ultrahigh dielectric constant

In the work, the (1-x)Ba0.85Ca0.15Zr0.08Ti0.92-xGe (abbreviated as BCZT-xGe) lead-free piezoelectric ceramics were successfully prepared by conventional solid-state reaction method. The authors studied the effects of GeO2 on phase transition behavior and piezoelectric, ferroelectric and dielectric properties of BCZT-xGe ceramics. The results showed that piezoelectric activity of ceramics were dramatically enhanced by doping GeO2, and the piezoelectric coefficient (d(33)) reached the maximum of 348 pC/N at x = 0.03 wt%, which is close to orthorhombic-tetragonal (O-T) phase boundary. Besides, ultrahigh dielectric constant (epsilon(r) = 40000) was obtained at x = 0.03 wt%. When x = 0.03 wt%, the remnant polarization (P-r) and coercive field (E-c) were 139 mu C/cm(2) and 0.47 kV/mm, respectively. Consequently, the properties were optimized at x = 0.03 wt%.