The influence of oxygen vacancies and La doping on the surface structure of NaTaO3

Doping of the semiconductor photocatalyst NaTaO3 with La is known to produce stepped features on the surfaces. Similar stepped-surface features can be produced in the undoped material by repeated high temperature calcination. In this work, density functional theory calculations for both La-doped and undoped NaTaO3 bulk and surfaces have been carried out to explore the hypothesis that La doping and high T calcination produce a common effect that favors the formation of stepped surfaces. It is found that La doping and oxygen vacancies lead to similar zig-zag distortions in the surface structure. It is suggested that this zig-zag distortion may induce the formation of the stepped-surface structures. (C) 2015 Elsevier B.V. All rights reserved.