Ferroelectric properties of BaTiO3-BiScO3 weakly coupled relaxor energy-storage ceramics from first-principles calculations

Abstract

Weakly coupled relaxor ferroelectrics BaTiO3-BiMeO3 (Me symbolizes trivalent or averagely trivalent cations) have received growing interest for energy-storage applications due to their extremely low remnant polarizations and slim hysteresis, which therefore provides high energy density and energy efficiency. Although large experimental progress has been made, there is still a lack of theoretical understanding from the electronic and atomic point of view. In this paper, by targeting the prototypical BaTiO3-BiScO3 (BT-BS) weakly coupled energy-storage ceramics, we investigated the ferroelectric properties at the electronic and atomic scale using first-principles calculations coupled with a phenomenological theory model. Results show that the lattice volumes expand with the increase of BS content, and an indirect band structure was found for the BT-BS ceramics. Ferroelectric polarizations become reduced and hysteresis loops get slimmer with the addition of BS. Moreover, large ionic displacement disorder of Ti/Sc atoms and strong orbital hybridization of Bi/Ti atoms with O atoms were discovered, which should serve as an origin of the reduced ferroelectric polarization and contribute to the weakly coupled relaxor behavior of the BT-BS ceramics. The employed methods and conclusions in this work should also be applicable to other BaTiO3-BiMeO3 ceramic systems, shedding light on the further enhancement of energy-storage performance from the electronic and atomic scale.