Dielectric and electrocaloric responses of Ba(Zr0.2Ti0.8)O3 bulk ceramics and thick films with sintering aids

Large electrocaloric effect (ECE) has been reported in Ba(Zr_0.2Ti_0.8)O₃ (BZT) bulk ceramics near room temperature. The finding opens up opportunities for developing high performance EC ceramic based refrigeration. To further reduce the operating voltage and enhance the reliability of such EC material, we investigate synthesis of BZT thick films can be fabricated into multilayer EC modules using the commercial multilayer ceramic capacitor (MLCC) technology. However, the high (1450 °C) sintering temperature of BZT EC ceramics poses challenge for the MLCC with low-cost electrodes. This paper investigate sintering aids that can significantly reduce sintering temperature of BZT ceramics. The bulk and thick-film BZT with 1 wt% PbO and B₂O₃ were sintered at 1200 °C and exhibited high dielectric constant and low loss around room temperature. Dielectric and electrocaloric responses of thus fabricated BZT thick films are studied. The low temperature sintered BZT thick films with proper sintering aids exhibit high breakdown field and larger ECE than the bulk BZT, thus paving the way for the future transition to EC MLCC suitable for EC cooling systems.