High discharge energy density in novel K1/2Bi1/2TiO3-BiFeO3 based relaxor ferroelectrics

An increasing number of new dielectrics are being reported for the development of next-generation ceramic capacitors for power electronics used in clean energy technologies. Here, high discharge energy density (W dis ) ~6.1 J cm −3 with efficiency (η)~72% under a pulsed field (E max ) of 410 kV cm −1 is reported along with temperature stability up to 150 °C (E max = 200 kV cm −1 ) for 0.5 K 0.5 Bi 0.5 TiO 3 -0.42BiFeO 3 -0.08Sm(Mg 2/3 Nb 1/3 )O 3 (KBT-BF-SMN) bulk ceramics. The optimised composition is chemically heterogeneous but electrically homogenous, similar to several BiFeO 3 -based dielectrics reported previously and adding to the growing body of evidence that electrical (measured at weak-field) not chemical homogeneity is the best guide to increased E max and enhanced energy density. KBT-BF-SMN ceramics are therefore considered as promising candidates for pulsed power and power electronics applications. • Novel Pb-free K 1/2 Bi 1/2 TiO 3 -BiFeO 3 based high energy density ceramics. • High energy density ~6.1 J cm −3 at 410 kV cm −1 for bulk ceramics. • Desirable electrical homogeneity with highly-resistive electrical components. • Superior permittivity stability (130–600 °C) and pulsed discharge characteristics > 150 °C. • Excellent candidate for next-generation energy density ceramic capacitors.