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Wide bandgap tunability in complex transition metal oxides by site-specific substitution
Woo Seok Choi1, Matthew F Chisholm, David J Singh
1Oak Ridge National Laboratory, Materials Science and Technology Division, Oak Ridge, Tennessee 37831, USA.
Abstract:
Fabricating complex transition metal oxides with a tunable bandgap without compromising their intriguing physical properties is a longstanding challenge. Here we examine the layered ferroelectric bismuth titanate and demonstrate that, by site-specific substitution with the Mott insulator lanthanum cobaltite, its bandgap can be narrowed by as much as 1 eV, while remaining strongly ferroelectric. We find that when a specific site in the host material is preferentially substituted, a split-off state responsible for the bandgap reduction is created just below the conduction band of bismuth titanate. This provides a route for controlling the bandgap in complex oxides for use in emerging oxide optoelectronic and energy applications.
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