Enhanced electrocaloric performance within wide temperature span in Al-doped BaZr0.2Ti0.8O3 ceramics

Al-doped BaZr 0.2 Ti 0.8 O 3 (BZT20) ceramics were prepared by solid-state sintering, and the relaxation degree of phase transition was tailored effectively. The microstructure, dielectric properties, ferroelectric properties, and electrocaloric (EC) performance of Al 2 O 3 -doped BZT20 ceramics were studied, respectively. The results show that Al 2 O 3 doping induces changes in Curie temperature and dielectric properties. When the additive amount of Al 2 O 3 is 1.25 at.%, the Curie temperature drops to around room temperature (RT), and the dielectric loss is lower than that of pure BZT20 ceramics. The diffusion constant γ reaches a minimum value of 1.57 when the Al 2 O 3 content is 1.25 at.%, indicating that a relatively large latent heat would be gathered while there is a phase transition. As a result, an enhanced EC response of ∆ T max  = 0.293 K near RT is obtained when the Al 2 O 3 content is 1.25 at.%, which is 1.6 times that of pure BZT20. It is also impressive that a wide working temperature range can be obtained, that is, T span  = 73 K for BZT20 ceramics with 1 at.% of Al 3+ ionic content.