Enhanced breakdown strength and energy storage density in a new BiFeO3-based ternary lead-free relaxor ferroelectric ceramic

摘要： A new ternary lead-free relaxor ferroelectric ceramic of (0.67-x)BiFeO3-0.33(Ba0.8Sr0.2)TiO3-xLa(Mg2/3Nb1/3)O3+y wt.% MnO2+z wt.% BaCu(B2O5) (BF-BST-xLMN+y wt.% MnO2+z wt.% BCB) was prepared by a solid-state reaction method. The substitution of LMN for BF was believed to induce a typical dielectric relaxation behavior owing to the increased random fields. After co-doping MnO2 and BCB, a significant decrease in the conductivity and grain size was simultaneously realized, resulting in obviously enhanced dielectric breakdown strength and energy-storage performances at room temperature. A high recoverable energy storage density W~3.38 J/cm3 and an acceptable energy storage efficiency η~59% were achieved in the composition with x=0.06, y=0.1 and z=2 under a measuring electric field of 23 kV/mm. In addition, the energy-storage performance is quite stable against both frequency (0.1 Hz-100 Hz) and temperature (30-170 oC), suggesting that BF-BST-xLMN+y wt.% MnO2+z wt.% BCB lead-free relaxor ferroelectric ceramics might be a promising dielectric material for high-power pulsed capacitors.