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Lead-free 0.5BaZr0.2Ti0.8O3–0.5Ba0.7Ca0.3TiO3 (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 Ps ~ 110 µC cm−2, remnant polarization Pr ~ 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]

This paper investigates the crystal structure, ferroelectric, temperature-dependent leakage current conduction mechanism and the piezoresponse force microscopy (PFM) behaviours of (Ba0.955Ca0.045) (Zr0.17Ti0.83)O3–BZT–BCT () films at the vicinity of the morphotropic phase boundary (MPB) of the [(1  −  x) BaZr0.20Ti0.80O3–xBa0.70Ca0.30TiO3] () composition. Epitaxial BZT–BCT thin films were grown on conductive La0.5Sr0.5CoO3 (LSCO) layers coated onto MgO (1 0 0) single-crystal substrates by pulsed laser deposition (PLD). High resolution x-ray diffraction (HR-XRD) reciprocal space maps (RSMs) confirmed the epitaxy with in-plane tetragonal symmetry (c  <  a), and Raman spectra also revealed a tetragonal perovskite crystalline lattice structure. Polarisation studies demonstrate that BZT–BCT films exhibit a high saturation polarisation of 148 µC cm−2 and a high recoverable (discharged) energy-storage density of 39.11 J cm−3 at 2.08 MV cm−1. Temperature-dependent P–E hysteresis loops resulted in a decrease in polarisation. Temperature-dependent leakage current behaviour was obtained and possible conduction mechanism is discussed. PPFM images revealed switchable ferroelectric piezoelectric contrasts after the application of a  ±9 V dc voltage on the conductive tip of the piezoresponse force microscope. [ABSTRACT FROM AUTHOR]