Observation of large enhancement in energy-storage properties of lead-free polycrystalline 0.5BaZr 0.2 Ti 0.8 O 3 –0.5Ba 0.7 Ca 0.3 TiO 3 ferroelectric thin films

Lead-free 0.5BaZr 0.2 Ti 0.8 O 3 –0.5Ba 0.7 Ca 0.3 TiO 3 (BZT–BCT) thin films were deposited on Pt(1 1 1)/TiO 2 /SiO 2 /Si substrates by pulsed laser deposition. The optimal ferroelectric response with a high saturation polarization P s ~ 110 µ C cm −2 , remnant polarization P r ~ 32.5 µ C 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.