Upper limit of the electrocaloric peak in lead-free ferroelectric relaxor ceramics

The electrocaloric effect (ECE) of two compositions (x = 0.06 and 0.07) of (1-x)(Na0.5Bi0.5)TiO3-xKNbO(3) in the vicinity of the morphotropic phase boundary is studied by direct measurements. Delta T-max = 1.5 K is measured at 125 degrees C under 70 kV/cm for NBT-6KN while Delta T-max = 0.8 K is measured at 75 degrees C under 55 kV/cm for NBT-7KN. We show that the shoulder, TS, in the dielectric permittivity, marks the upper limit of the ECE peak under high applied electric fields. These results imply that the range of temperature with high ECE can be quickly identified for a given composition, which will significantly speed up the process of materials selection for ECE cooling. (C) 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license.