Effect of zinc and strontium Co-doping on the A site of BaTiO3: An atomic scale study

Abstract

Barium titanate (BaTiO₃) exhibits photo-catalytic performance, although its performance is often limited by its wide bandgap, which restricts its ability to absorb visible light. Herein, we explore the effects of co-doping zinc (Zn) and strontium (Sr) at the A-site in barium titanate. Our study reveals that the co-doping could change the band structures and promote the carrier mobility of the catalysts to result in good photocatalytic activities. The co-doped material exhibits a reduced bandgap compared to pristine BaTiO₃ (BTO) and transitions to an indirect bandgap type. These modifications enhance both conductivity and light absorption capabilities, highlighting the positive impact of our doping strategy on Ba_0.75Zn_0.125Sr_0.125TiO₃ (BZSTO). From the analysis of the electron density in pure BTO and Zn, Sr co-doped BTO, we suggest that the indirect band gap observed after co-doping are attributed to the increased electron density on one side of the Ti atom. The split charge distribution of the oxygen atoms aligned within the crystal structure can influence the movement of photogenerated carriers. The new findings advance our understanding of (Zn, Sr) co-doped BaTiO₃ and bolster the design and development of materials with potential electro-optical properties.