Influence of thermal conditions on the electrocaloric effect in a multilayer capacitor based on doped BaTiO3

Abstract

We present the results of studies of thermal expansion, heat capacity, permittivity, polarization and the influence of different thermal conditions on the intensive electrocaloric effect (ECE), [Formula: see text], in a commercial multilayer capacitor based on doped BaTiO3. Investigations in a wide temperature range revealed one anomaly in the behavior of the physical properties at about 290[Formula: see text]K characteristic for the relaxors. Direct measurements showed a high reversibility of ECE under equilibrium thermal conditions. Good agreement was found between the values of [Formula: see text] determined by direct and indirect measurements at the electric field up to 15.4[Formula: see text]kV/cm. Quasi-isothermal conditions lead, firstly, to decrease of large [Formula: see text]0.94[Formula: see text]K obtained in adiabatic conditions under [Formula: see text][Formula: see text]kV/cm to 0.87[Formula: see text]K, and, secondly, the appearance of a difference between the values of [Formula: see text] and [Formula: see text] determined when the electric field is applied and removed. Using this phenomenon and changing the frequency of the periodic electric field, [Formula: see text][Formula: see text]kV/cm, the effect of cooling was obtained equal to [Formula: see text][Formula: see text]K. The results obtained are useful for further development of the electrocaloric refrigeration technique without thermal switches.