Effective band gap engineering in multi-principal oxides (CeGdLa-Zr/Hf)Ox by temperature-induced oxygen vacancies

Yixuan Hu; Mariappan Anandkumar; Joydip Joardar; Xiaodong Wang; Atul Suresh Deshpande; Kolan Madhav Reddy

doi:10.1038/s41598-023-29477-0

Effective band gap engineering in multi-principal oxides (CeGdLa-Zr/Hf)O_x by temperature-induced oxygen vacancies

Sci Rep. 2023 Feb 9;13(1):2362. doi: 10.1038/s41598-023-29477-0.

Authors

Yixuan Hu¹, Mariappan Anandkumar², Joydip Joardar³, Xiaodong Wang¹, Atul Suresh Deshpande², Kolan Madhav Reddy⁴

Affiliations

¹ State Key Laboratory for Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
² Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Sangareddy, 502285, India.
³ International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur P.O., Hyderabad, Telangana, 500005, India.
⁴ State Key Laboratory for Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China. kmreddy@sjtu.edu.cn.

Abstract

Oxygen vacancy control has been one of the most efficient methods to tune the physicochemical properties of conventional oxide materials. A new conceptual multi-principal oxide (MPO) is still lacking a control approach to introduce oxygen vacancies for tuning its inherent properties. Taking multi-principal rare earth-transition metal (CeGdLa-Zr/Hf) oxides as model systems, here we report temperature induced oxygen vacancy generation (OVG) phenomenon in MPOs. It is found that the OVG is strongly dependent on the composition of the MPOs showing different degrees of oxygen loss in (CeGdLaZr)O_x and (CeGdLaHf)O_x under identical high temperature annealing conditions. The results revealed that (CeGdLaZr)O_x remained stable single phase with a marginal decrease in the band gap of about 0.08 eV, whereas (CeGdLaHf)O_x contained two phases with similar crystal structure but different oxygen vacancy concentrations causing semiconductor-to-metal like transition. Due to the intrinsic high entropy, the metallic atoms sublattice in (CeGdLaHf)O_x remains rather stable, regardless of the interstitial oxygen atoms ranging from almost fully occupied (61.84 at%) to almost fully empty (8.73 at%) state in the respective crystal phases. Such highly tunable oxygen vacancies in (CeGdLa-Zr/Hf) oxides show a possible path for band gap engineering in MPOs for the development of efficient photocatalysts.

Abstract

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