The electrocaloric effect in BaTiO3:Eu ceramics determined by an indirect method.

The electrocaloric effect (ECE) was investigated in BaTiO3 ceramics, pure and doped with 2% of Eu3+ ions. The temperature and electric field dependences of ECE were investigated by the indirect method. Based on Maxwell relations, the ECE was characterized via P–T curves under different electric fields. The ECE experiments have been carried out from room temperature through the phase transition region and in the paraelectric phase. A normal positive ECE was found around the phase transition point and is of the order of 0.6 K for pure BaTiO3 and 0.15 K for the BT doped with Eu ions. The abnormal negative ECE was detected for the BaTiO3 ceramic doped with Eu ions above the temperature of the phase transition. This phenomenon was related to the existence of defects that originates from the fixed local polarization of defect dipoles. [ABSTRACT FROM AUTHOR]