Structural-distortion-driven relaxor ferroelectric behavior and energy storage properties of Na0.25Bi0.25Ba0.3Sr0.2TiO3 perovskite synthesized using the molten salt method

The growing demand for environmentally sustainable energy-storage technologies has accelerated research into lead-free dielectric ceramics. In this work, [Formula: see text][Formula: see text][Formula: see text][Formula: see text]TiO 3 (NBBST) ceramics were synthesized via a molten-salt route using a KCl/K 2 SO 4 eutectic flux, enabling phase formation at relatively lower temperatures. X-ray diffraction and profile refinement confirmed a single-phase perovskite with dominant tetragonal (P4mm) symmetry. Raman spectra and structural refinement revealed octahedral distortion associated with local structural disorder, consistent with relaxor characteristics. Scanning electron microscopy (SEM) micrographs showed a dense microstructure with clearly defined grain boundaries, and EDX verified the desired elemental distribution without salt-related contamination. Dielectric measurements exhibited a broad and dielectric constant peak with a Curie temperature of [Formula: see text]C, a diffuseness parameter [Formula: see text] and a frequency-dependent shift, confirming relaxor ferroelectric behavior. Slim [Formula: see text] hysteresis loops demonstrated reversible dipolar switching, yielding a recoverable energy density of 537.90[Formula: see text]mJ/cm 3 and an efficiency above 80.12% at 95[Formula: see text]kV/cm. These results highlight NBBST as a promising lead-free relaxor ceramic for high-efficiency dielectric energy-storage applications.