Ba 2+ /Sr 2+ regulation in A‐site vacancy‐engineered B 0.015+1.5 x S 0.245‐1.5 x □ 0.03 BNT relaxor ceramics for energy storage

A‐site vacancy‐engineered Ba 0.015+1.5 x Sr 0.245‐1.5 x □ 0.03 Bi 0.385 Na 0.325 TiO 3 (B 0.015+1.5 x S 0.245‐1.5 x □ 0.03 BNT, x = 0, 0.012, 0.024, 0.036, 0.048, 0.06) ceramics were fabricated by a solid‐state reaction method. The effect of Ba/Sr regulation on the structure, polarization, and dielectric energy storage properties of the B 0.015+1.5 x S 0.245‐1.5 x □ 0.03 BNT ceramics were investigated. With the increase of the x value, the lamellar microdomains transform into the coexistence of banded domains and nanodomains. A double‐like P‐E hysteresis loop with a high polarization value ( P max > 35 μC/cm 2 ) can be obtained at a very low electric field of 60 kV/cm. Consequently, a large recoverable energy storage density ( W rec = 2.33 J/cm 3 ) can be achieved at a relatively low applied electric field of 130 kV/cm. The designed B 0.087 S 0.173 □ 0.03 BNT also exhibits high dielectric constant ( ε r = 3510 @150°C&1 kHz) with suitable temperature capacitance coefficient (TCC 150°C = ±15%) over the temperature range of 17°C∼382°C. These findings provide a novel vacancy‐engineered avenue towards the design of BSBNT relaxor ceramics with high W rec and good stability for low‐voltage driven high‐temperature pulsed power capacitor.