Multifunctionality of lead-free BiFeO3-based ergodic relaxor ferroelectric ceramics: High energy storage performance and electrocaloric effect

Abstract With industrializations speeding up, the need for materials with multiple functions are growing because of ever-increasing complexity of electronic devices. The BiFeO3- based ferroelectric relaxor ceramic as a multifunctional material has been ignored thus far. This work innovatively investigates the multifunctionality in a novel lead-free BiFeO3-BaTiO3-(Sr0.7Bi0.2)TiO3 relaxor ferroelectric ceramics since a high energy storage performance and electrocaloric effect are simultaneously obtained. Results show that a large adiabatic temperature change ΔT∼1.44 K is achieved. The total energy storage density (WS) reaches to ∼2.34 J/cm3, recoverable energy storage density (WR) are ∼1.74 J/cm3, accompanied by a high efficiency η∼74%. The charge- discharge characterizations indicate that this ceramic possesses an ultrahigh current density of 1184.7 A/cm2 and power density of 59.2 MW/cm3. In particular, the discharging speed is ultra-fast and the discharging period τ is in range of 25–30 ns at room temperature. This work strongly indicates that the studied ceramic is a promising candidate in multifunctional applications such as cooling devices and pulsed power electronics and also enrich the species of the lead-free materials in multifunctionality.