Band gap tuning in ferroelectric Bi4Ti3O12 by alloying LaTMO3 (TM = Ti, V, Cr, Mn, Co, Ni, and Al)

TL;DR

This study demonstrates how alloying Bi4Ti3O12 with various LaTMO3 compounds can significantly reduce its band gap, especially with LaCoO3, enhancing its potential for optoelectronic applications.

Contribution

It introduces a method of band gap tuning in ferroelectric Bi4Ti3O12 through site-specific alloying with LaTMO3 compounds, highlighting the impact of transition metal incorporation.

Findings

Band gap reduction observed with LaTMO3 alloying.

Largest band gap decrease of ~1 eV with LaCoO3.

Alloying with Mott insulators effectively reduces band gap.

Abstract

We fabricated ferroelectric Bi4Ti3O12 (BiT) single crystalline thin films site-specifically substituted with LaTMO3 (TM = Al, Ti, V, Cr, Mn, Co, and Ni) on SrTiO3 substrates by pulsed laser epitaxy. When transition metals are incorporated into a certain site of the BiT, some of BiT-LaTMO3 showed a substantially decreased band gap, coming from the additional optical transition between oxygen 2p and TM 3d states. Specifically, all alloys with Mott insulators revealed a possibility of band gap reduction. Among them, BiT-LaCoO3 showed the largest band gap reduction by ~1 eV, positioning itself as a promising material for highly efficient opto-electronic devices.