Energy storage and dielectric properties in PbZrO3/PbZrTiO3 antiferroelectric/ferroelectric bilayer bulk structure using Landau theory.

Employing Landau theory and the Landau–Khalatnikov (L–K) equation of motion, we investigate the phase transitions in individual layers of antiferroelectric lead zirconate (PbZrO₃), ferroelectric lead zirconate titanate (PbZrTiO₃), and an antiferroelectric/ferroelectric PbZrO₃/PbZr_(0.21)Ti_(0.79)O₃ bilayer bulk structure. We examine the dielectric hysteresis loop behavior of the three systems, with a specific focus on the PbZrO₃/PbZr_(0.21)Ti_(0.79)O₃ bilayer under different stabilities of the PbZrO₃ layer. In addition, we explore cases where the coercive field of the bilayer structure is lower than that of the PbZrTiO₃ individual layer. The recoverable electric energy for the PbZrO₃/PbZr_(0.21)Ti_(0.79)O₃ bilayer increases significantly to 118 J/cm³ at an applied field of 7.5 × 10⁸ V/m at 20 °C. In comparison, the PbZr_(0.21)Ti_(0.79)O₃ layer reaches 71.8 J/cm³ under the same field and temperature conditions. This is much higher than those predicted experimentally by previous studies on thin film single and bilayer structures (15.6 and 28.2 J/Cm³ respectively), indicating that the antiferroelectric/ferroelectric PbZrO₃/PbZr_(0.21)Ti_(0.79)O₃ bilayer bulk structure could be used to target specific large-scale, long-term energy storage applications. Upon increasing the value of the coupling coefficient, the transition temperatures of the PbZrO₃ layer and the PbZrO₃/PbZr_(0.21)Ti_(0.79)O₃ bilayer are increased up to the transition temperature of the PbZr_(0.21)Ti_(0.79)O₃ individual layer (450 °C). This increment in the transition temperature in the bilayer system contributes to its stability in storing energy at higher temperatures. Furthermore, the recoverable energy density of the PbZrO₃/PbZr_(0.21)Ti_(0.79)O₃ bilayer increases further with temperature from 20 to 440 °C correlated with the rise in the difference between the spontaneous and the remanent polarizations (P_s − P_r). The significant stored energy observed over a wide temperature range highlights the promise of this bilayer structure for creating high-power capacitors where stability at different temperatures is crucial and possesses greater energy storage capacity. [ABSTRACT FROM AUTHOR]