Relation between dielectric permittivity and electrocaloric effect under high electric fields in the Pb(Mg1/3Nb2/3)O3-based ceramics

The correlation between dielectric permittivity and electrocaloric (EC) temperature change (Delta T-EC) has been investigated in (1-x)Pb(Mg1/3Nb2/3)O-3-xPbTiO(3) (PMN-100xPT, with x=0, 0.05, and 0.10) relaxor ferroelectric ceramics. At a given electric field, both peak temperatures, including the temperature of the permittivity peak (T-m) and the temperature of the maximum of the Delta T-EC (T-ECmax) increase with increasing PT content. The peak of the dielectric permittivity is, regardless of the applied electric field, always at a higher temperature than is the T-ECmax, and the temperature gap between both maxima progressively increases with increasing applied DC bias. This is particularly true above the threshold field, which induces the long-range ordered ferroelectric state. The results, which are explained in terms of the electric field-temperature phase diagram of relaxor systems, thus reveal that T-m can only roughly mark the temperature of the upper boundary of the temperature-electric field window, where the EC responsivity (Delta T-EC/Delta E) is the highest.