Enhanced energy storage density and efficiency in Sm 3+ -doped ((Bi 0.5 Na 0.5 ) 0.7 (Sr 0.7 Bi0.2) 0.3 ))TiO 3 ceramics

Lead-free ceramics ((Bi 0.5 Na 0.5 ) 0.7 (Sr 0.7 Bi 0.2 ) 0.3 ) 1- x Sm x )TiO 3 ( x = 0.0, 0.005, 0.01, 0.02, 0.03) with a novel phase boundary structure were successfully synthesized. All samples sintered well and shown pure perovskite structure. The doping of Sm 3+ inhibits the grain growth and enhanced the relaxor properties. Besides, the activity of polar nanoregion (PNRs) is improved. Ferroelectric analysis showed that proper Sm 3+ doping played a pegging role on the saturated polarized P m , leading to a higher and slimmer P-E loop. As a result, a large energy storage density (~ 1.25 J/cm 3 ) with high energy efficiency (~ 73%) were achieved at x = 0.005 under an electric field of 90 kV/cm. Further, the sample was found to have good temperature stability between room temperature and 110 °C. This study shows that ceramic material has great potential for the application of high-temperature stability energy storage capacitors.