Enhanced room temperature electrocaloric effect in lead-free relaxor ferroelectric NBT ceramics with excellent temperature stability

Solid-state refrigeration based on electrocaloric effect (ECE) is a high efficiency and eco-friendly refrigeration technique, which has attracted increasing attention. However, it is still a challenge to realize a large adiabatic temperature change (∆T) accompanied by wide operating temperature range (Tspan). Herein, enhanced room temperature ECE was realized in lead-free (1-x)Na0.5Bi0.5TiO3-xSr0.85Bi0.10TiO3 (NBT-xSBT) by a synergistic effect of forming relaxor ferroelectric and constructing multilayer ceramic capacitor (MLCC). It is found that the maximum ∆T of NBT-0.50SBT ceramic is 0.31 K at 80 kV/cm, and Tspan is up to 60 K. To further improve the breakdown strength (BDS), NBT-0.50SBT MLCC was fabricated by a tape-casting method. A large ECE of MLCC reached 2.59 K at 60 °C with excellent temperature stability from 35 °C to 95 °C. These results indicate that NBT-based material is a promising electrocaloric material for solid-state cooling applications.