Influence of 90° charged domain walls on the electrocaloric effect in PbTiO3 ferroelectric thin films.

The electrocaloric (EC) effect in PbTiO3 ferroelectric thin films (FETFs) with an array of partially compensated head-to-head (HH) and tail-to-tail (TT) 90° charged domain walls (CDWs) has been studied by using a phase field method. The calculation results indicate that the magnitude of the adiabatic temperature change ΔT increases with the diminution of the charge density (ρ*), in which ρ* is provided by charged defects or band bending. In particular, a negative EC effect caused by the direction difference between the applied electric field and the dipole is found near the HH and TT domain walls when ρ*>2.0. The EC strength |ΔT|/|ΔE| is 0.020 K cm kV-1 with the positive ΔT = 2.03 K at the external dimensionless electric field Eb*=0.08 (ΔE=104kV cm-1). These results indicate that the CDWs can provide an efficient way to adjust the EC effect of FETFs for refrigeration applications at room temperature. [ABSTRACT FROM AUTHOR]