Migrations of oxygen vacancy in tungsten oxide (WO3): A density functional theory study

• Published in: Computational materials science Vol. 90; pp. 171 - 176
• Main Authors: Le, Hung M., Vu, Nam H., Phan, Bach-Thang
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.07.2014; Elsevier
• Subjects: Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; DFT; Exact sciences and technology; NEB; Oxygen vacancy; Physics; Point defects (vacancies, interstitials, color centers, etc.) and defect clusters; Structure of solids and liquids; crystallography; VO migration; WO3; VO migration; WO3; NEB; DFT; Oxygen vacancy; Defect density; Electronic density of states; Energy barrier; Tungsten oxide; Vacancy motion; Diffusion barriers; V; Density functional method; migration; WO; Polymorphism
• ISSN: 0927-0256; 1879-0801
• DOI: 10.1016/j.commatsci.2014.04.018

[Display omitted] •We present a DFT study of oxygen vacancy diffusion in tungsten oxide.•VO migrations are concluded to occur most favorably in WO2.984 (lowest oxygen-defect concentration).•Comparisons between PBE and PW91 calculations show good consistency between two calculations. In this paper, we present a theoretical study of oxygen vacancy (VO) diffusions in tungsten oxide (WO3) using density functional theory approaches. By employing PBE calculations, we investigate the energy profiles of VO migrations in three different WOx models: WO2.984 (2×2×2 supercell), WO2.938 (1×2×1 supercell), and WO2.875 (one primary unit cell). It is found that the lowest energy barrier is 0.14eV when VO migrates from the –W–(O)–W– chain in the z axis to that in the y axis in WO2.938, while the VO migrations between the –W–(O)–W– linkage in x and y axis in the same structure are found to have a larger barrier (0.867 and 1.074eV for the forward and backward reactions, respectively). We suggest that VO migrations are most likely to occur in WO2.984 (lowest oxygen-defect concentration), while the VO migrations do not preferentially occur in WO2.938. Additional PW91 calculations are executed for the VO migrations in WO2.875 to compare with PBE results. Overall, we have found that PBE and PW91 establish very good agreement in predicting relative energies of different VO structures and VO migration barriers with an average percent difference of 10.6%.