Strongly enhanced electrocaloric effects in doped BaTiO3 with reduced grain size

Ferroelectrics are promising candidates in the field of green solid state refrigeration technology due to showing a thermal response with the application/removal of an electric field. However, thermal responses of ferroelectrics are too low; at present, this approach is not able to compete with the conventional refrigeration approach. Guzman-Verri et al (2016 APL Materials 4, 064106) theoretically predicted that the thermal response of ferroelectrics can be elevated up to a considerable amount via modulation of the correlation length of the fluctuation of polarization. In this letter, we report a giant electrocaloric response (-Delta S-E = 16.8 J/kg-K) in 1 wt%Bi2O3-BaTiO3, via manipulation of micro-structural configuration. Addition of Bi2O3 during the sintering process is responsible for the growth of grains of small size, which alters the fluctuation of polarization and reduction in the domain wall, thereby increasing the thermal response. The dielectric properties of Bi2O3 added BaTiO3 remain similar to the bare BaTiO3.