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Oxygen vacancy defects in tantalum pentoxide: a density functional study

  • R. Ramprasad (a1), Michael Sadd (a2), Doug Roberts (a2), Tom Remmel (a1), Mark Raymond (a2), Eric Luckowski (a2), Sriram Kalpat (a2), Carole Barron (a2) and Mel Miller (a1)...

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).

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Oxygen vacancy defects in tantalum pentoxide: a density functional study

  • R. Ramprasad (a1), Michael Sadd (a2), Doug Roberts (a2), Tom Remmel (a1), Mark Raymond (a2), Eric Luckowski (a2), Sriram Kalpat (a2), Carole Barron (a2) and Mel Miller (a1)...

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