First principle studies of TiO2-ZnO alloys under high pressure

Mengxin Yang; Yanling Zhang; Min Liang; Yuanming Sun; Defang Duan; Fubo Tian

doi:10.1088/1361-648X/ac9f9a

First principle studies of TiO₂-ZnO alloys under high pressure

J Phys Condens Matter. 2022 Nov 11;51(2). doi: 10.1088/1361-648X/ac9f9a.

Authors

Mengxin Yang¹, Yanling Zhang¹, Min Liang¹, Yuanming Sun¹, Defang Duan¹, Fubo Tian¹

Affiliation

¹ State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, People's Republic of China.

PMID: 36322990
DOI: 10.1088/1361-648X/ac9f9a

Abstract

The ZnO-TiO₂composite system has been applied as a photocatalyst in the treatment of organic waste and domestic wastewater due to its high separation rate of photogenerated carriers and wide light response range. Using the first-principles approach based on density functional theory, we investigated the crystal structures and the electronic properties of ZnO-TiO₂alloys under high pressure and predicted three stable high-pressure phases (CmcmZnTiO₃,ImmaZn₂TiO₄andCmZnTi₃O₇). Calculations of the phonon spectra and elastic constants showed that the predicted structures are dynamically and mechanically stable. In terms of electronic properties, it was found that the three crystal structures were all semiconductors. With the increase of pressure, the band gap ofCmZnTi₃O₇showed an increasing trend, while the band gap ofCmcmZnTiO₃andImmaZn₂TiO₄gradually decreased. The calculated band structures showed that the band gap first increases nonlinearly and then decreases as the Zn concentration increases. Pressure can regulate the band gap of the above crystals, making them promising for applications in photocatalysis and microwave devices.

Keywords: ZnO-TiO2 alloys; band gap; first-principle calculation; high pressure; phase transition.