Energy storage properties influenced by relaxor ferroelectric properties dependent on the growth direction of epitaxial Bi2SiO5 thin films

Abstract

Ferroelectric Bi2SiO5 (BSO) thin films were deposited by pulsed laser deposition on Nb-doped (100), (110) and (111) SrTiO3 (Nb:STO) substrates, resulting in (001)-, (113)- and (204)-oriented epitaxial films. Due to the crystallinity of BSO, in which the Bi2O2 layers are formed perpendicular to the c-axis direction, the (001)-oriented epitaxial BSO thin film showed the lowest remanent polarization and the best leakage current characteristics. On the other hand, the (113)- and (204)-oriented films showed an increase in remanent polarization due to the improvement of a-oriented crystallinity. Through experiments using vertical and lateral piezoresponse force microscopy, it has been confirmed that the distribution of in-plane-oriented domains reducing remanent polarization decreases in the order of (001)-, (113)- and (204)-oriented epitaxial BSO thin films. The epitaxial BSO thin films that exhibit ferroelectric hysteresis loops similar to the relaxor ferroelectric thin films tended to have improved energy storage characteristics as a result of improved remanent polarization and saturation polarization. In particular, the (113)-oriented epitaxial BSO thin film showed a high recoverable energy density of about 41.6 J cm−3 and an energy storage efficiency of about 85.6%.