Collaboratively improved energy density and efficiency in NaNbO3-based lead-free relaxor ferroelectrics via enhancing antiferrodistortion†
Abstract
High-performance relaxor ferroelectrics for energy-storage capacitors have attracted enormous attention, but the difficulty in simultaneously enhancing energy density (Wrec) and efficiency (η) largely hinders their development. Herein, we introduce an effective strategy to collaboratively improve Wrec and η values in NaNbO3-based lead-free relaxor ferroelectric (FE) ceramics through enhancing the antiferrodistortion of the FE superlattice, realizing an excellent comprehensive energy-storage performance of Wrec ∼ 8.5 J cm−3 and η ∼ 90%. Both the local FE orthorhombic supercells with a significantly enhanced antiferrodistortive degree and the formation of highly concentrated stripe-like polar nanodomains should be responsible for the markedly delayed polarization saturation, the suppressed polarization hysteresis and the maintained maximum polarization. These structural features also ensure outstanding temperature-insensitive charge–discharge properties of high-power density ∼343 ± 6% MW cm−3, high discharge energy density ∼4.3 ± 10% J cm−3 and ultra-short discharge time <30 ns at 0–150 °C, demonstrating great application potential in next-generation advanced pulse power capacitors. As a result, enhancing antiferrodistortion should be a valuable way to develop novel high-performance relaxor ferroelectric capacitors.