The Electrocaloric Effect in BaTiO3 Thick Film Multilayer Structure at High Electric Field
We demonstrated the superior electrocaloric effect (ECE) in BaTiO3 multilayer structure. The sample fabricated by tape-casting process has 120 effective ferroelectric layers with average layer thickness of 1.7 μm. The ferroelectric hysteresis loops were measured in the temperature range from 30 to 180 oC, and then the temperature dependences of ECE adiabatic temperature change and heat absorption were obtained according to Maxwell relation. A peak ECE adiabatic temperature change of 0.027 K/V and heat absorption of 0.36 J/g were observed near the ferroelectric phase transition at 125 oC under Vmax=25 V. The BaTiO3 thick film can sustain an external electric field (>500 kV/cm) several times higher than bulk ferroelectric ceramics (~30 kV/cm). Although the EC coefficient of BaTiO3 is much lower than lead-based ferroelectric ceramics, the ultrahigh working electric field endows it a large ECE, higher than that of most reported lead-based ferroelectric ceramics. In addition, the lead-free composition provides it a promising future in solid-state cooling technology.