Oxygen vacancy defects in tantalum pentoxide: a density functional study

Abstract

First principles total energy calculations were performed in order to characterize O vacancy defects in Ta2O5. A simplified version of the crystalline orthorhombic phase of Ta2O5 was used in this study. Results indicate that O vacancies in Ta2O5 can be broadly classified based on their location in the lattice. One type of vacancies (occupying the “in-plane” sites) displays deep or mid gap occupied states, and shallow unoccupied states, while a second type (occupying “cap” sites) results in shallow occupied states. For a wide range of local Fermi level or chemical potential, the neutral and +2 charged states of the in-plane type vacancy and the +2 charge state of the cap type vacancy are found to be most stable. Migration energies of the two types of vacancies in the neutral and +2 charge states are markedly different, with the “cap” type of vacancies displaying very high barriers to migration (∼ 5 eV) compared to the “in-plane” type (∼ 0.5–1.0 eV).

Effects of Ta2O5 Surface Modification by NH3 on the Electronic Structure of a Ru-Complex/N–Ta2O5 Hybrid Photocatalyst for Selective CO2 Reduction

“…The Ta− O bond lengths were within the range of 1.899−2.139 Å with an average value of 1.988 Å and thus in good agreement with reported experimental results. 68 The calculation results also suggested that Ta 16 O 40 has electronic properties similar to those of bulk Ta 2 O 5 . Figure 4a shows the highest occupied molecular orbital (HOMO) and LUMO of Ta 16 O 40 , which are derived from the O 2p and Ta 5d orbitals, respectively.…”