Orientation dependence of the electrocaloric effect in PbTiO _3 SrTiO _3 multilayers

摘要

A phenomenological thermodynamic model is presented to investigate the effects of the orientation and the relative thickness of SrTiO _3 layer on the electrocaloric effect in PbTiO _3SrTiO _3 multilayers. Theoretical calculations show that complete polarization suppression and a large electrocaloric effect take place at the critical relative thickness of SrTiO _3 layer of 46, 33, and 30 for the (001), (110), and (111) oriented PbTiO _3SrTiO _3 multilayers respectively, not occuring at the critical relative thickness of 63, 50, and 46 reported by Wu et al. H.P. Wu, A.P. Liu, L.Z. Wu, S.Y. Du, Appl. Phys. Lett. 93 (2008) 242909. Moreover, (111) oriented multilayers have the largest electrocaloric effect which is different from that of BaTiO _3SrTiO _3 multilayers where (110) oriented multilayers have the largest electrocaloric effect. Consequently, the electrocaloric effect of PbTiO _3SrTiO _3 multilayers can be adjusted by the orientation and the relative thickness of SrTiO _3 layer.