Direct electrocaloric measurements using a differential scanning calorimeter

The electrocaloric effect (ECE) in ferroelectric materials is a promising mechanism for the development of small, effective, low cost, and environmentally friendly solid state refrigerators. During the last decade, an increased interest has been paid to studies of this effect. Getting reliable values requires direct measurements of the ECE instead of the frequently used indirect estimates based on Maxwell´s relation. In this paper, we report on the modification of a differential scanning calorimeter for direct ECE measurements. The importance of proper estimation of the heat capacitance and thermal losses for the correct ECE measurements is discussed. The ECE was measured for bulk ceramics Ba(Zr_0.2Ti_0.8)O₃. The temperature change reaches a value of ΔT_EC= 0.44 K at 305 K under an electric field of 2 kV/mm. The obtained data are compared with results of the evaluation of the indirect ECE.