Enhancing Dielectric Breakdown Strength in BiFeO₃-SrTiO₃ Ceramics via Bi₂Ti₂O₇ Doping

Abstract (1- x )(0.7BiFeO₃-0.3SrTiO₃)- x Bi₂Ti₂O₇ ceramics (abbreviated as BFST- x BTO, where x = 0, 0.02, 0.04, 0.06, and 0.08) were synthesized via a solid-state reaction method. The BFST and BTO ceramic powders were separately prepared using the solid-state reaction approach. Subsequently, these two types of powders were homogeneously mixed to fabricate BFST- x BTO solid solution ceramics. X-ray diffraction (XRD) analysis confirms that BTO diffuses into the crystal lattice of BFST, forming perovskite solid solution ceramics. With the increase of BTO content, the average grain size of the ceramics decreases, while the band gap shows a corresponding increasing trend. Impedance analysis indicates that the conduction mechanism of the ceramics is dominated by oxygen vacancy hopping near the grain boundaries. Notably, the introduction of BTO leads to increased grain boundary density and an expanded band gap, which jointly contribute to the reduced dielectric loss and enhanced dielectric breakdown strength (E b ) of the ceramics. The E b , recoverable energy storage density (W rec ) and efficiency (η) for BFST without BTO doping are 140 kV/cm, 0.38 J/cm 3 and 10.67%. After BTO-doping, E b , W rec and η are all increased. The highest E b =420 kV/cm is obtained in BFST-0.04BTO ceramics. The W rec and η are 2.24 J/cm 3 and 34.74% for BFST-0.04BTO ceramics. With increasing BTO content to 0.08, The E b slightly decreases to 400 kV/cm, while the W rec and η increase to 3.38 J/cm 3 and 39.88%, respectively.