Observation of large enhancement in energy-storage properties of lead-free polycrystalline 0.5BaZr0.2Ti0.8O3–0.5Ba0.7Ca0.3TiO3 ferroelectric thin films.

Lead-free 0.5BaZr_0.2Ti_0.8O₃–0.5Ba_0.7Ca_0.3TiO₃ (BZT–BCT) thin films were deposited on Pt(1 1 1)/TiO₂/SiO₂/Si substrates by pulsed laser deposition. The optimal ferroelectric response with a high saturation polarization P_s ~ 110 µC cm⁻², remnant polarization P_r ~ 32.5 µC cm⁻² along with a coercive field of 0.18 MV cm⁻¹ was observed from the P–E hysteresis loops under an applied frequency of 1 kHz. A giant recoverable energy-storage density of 93.52 J cm⁻³ at an applied electric field ~3.47 MV cm⁻¹ was observed. The optimized BZT–BCT thin films exhibited a high dielectric constant with a low dielectric loss at room temperature like their bulk counterpart (high dielectric constant (Ɛ ~ 121 81)) and low dielectric loss (tan δ ~ 0.01–0.03) properties. OPP-PFM images revealed switchable ferroelectric distinct polarization contrasts on the application of a  ±12 V dc voltage on the conductive tip at room temperature. Observed enhanced dielectric, ferroelectric and energy density properties of BZT–BCT thin films are useful for next generation electrical energy storage applications. [ABSTRACT FROM AUTHOR]