晶粒尺寸对无铅0.4(Na0.5Bi0.5TiO3)–0.225BaTiO3–0.375BiFeO3伪三元陶瓷的结构、介电、铁电、压电及储能性能的影响

Lead free ferroelectrics are under the research spotlight owing to their prospective application in sensors, actuators, transducers and energy storage devices. The electrical and structural properties of lead-free ferroelectric ceramics is significantly influenced by the grain size, thereby impacting the energy storage performance. This study investigates the dependence of energy storage capabilities on the grain size for a specific lead-free pseudo ternary ferroelectric system 0.4(Na 0.5 Bi 0.5 TiO 3 )–0.225BaTiO 3 –0.375BiFeO 3 . The specimens with varying grain sizes were fabricated through the conventional solid-state synthesis route, with grain size modulation achieved through controlled sintering conditions. The relationship between grain size and key parameters such as dielectric constant, ferroelectric polarization, breakdown strength, and energy density is rigorously examined. X-ray diffraction (XRD) analysis confirmed phase purity and revealed subtle structural evolution with grain size variation. Scanning electron microscopy (SEM) illustrated uniform microstructures with well-defined grain boundaries and negligible porosity. The piezo response shows a sudden enhancement when grain size increases beyond 6 μm. The room temperature resistivity and dielectric breakdown strength show a systematic decrease with increase in grain size. Dielectric measurements demonstrated a relaxor like characteristics across the grain size ranges with coarser grain sized composition showing a more relaxor nature and higher “degree of ordering”. The energy storage density was evaluated through polarization–electric field ( P – E ) ferroelectric hysteresis loops. The highest energy storage density ~ 1.5 J/cm 3 was obtained at an optimized grain size ~ 6 µm owing to enhanced saturation polarization and reduced hysteresis. The high energy storage density is retained over a wide temperature range from room temperature to 175 °C. The complex inter-relationship between these factors is analyzed to optimize the material's performance for practical applications in energy storage devices. The findings provide crucial insights into tailoring grain size for maximizing energy storage performance in lead-free ferroelectrics, paving the way for the development of high-performance lead-free energy storage systems.