Design of a low band gap oxide ferroelectric: Bi6Ti 4O17

Abstract

A strategy for obtaining low band gap oxide ferroelectrics based on charge imbalance is described and illustrated by first-principles studies of the hypothetical compound Bi6Ti4O17, which is an alternate stacking of the ferroelectric Bi4Ti3O 12. We find that this compound is ferroelectric, similar to Bi 4Ti3O12 although with a reduced polarization. Importantly, calculations of the electronic structure with the recently developed functional of Tran and Blaha yield a much reduced band gap of 1.83 eV for this material compared to Bi4Ti3O12. Therefore, Bi6Ti4O17 is predicted to be a low band gap ferroelectric material. Copyright © 2011 EPLA.