Oxidation of Nb as studied by the uv-photoemission technique

Abstract

The initial stages in the oxidation of Nb have been studied by the uv‐photoemission technique for photon energies below 12 eV. Changes of structure in the electron distribution curves for different oxygen exposures and temperatures are correlated with formation of different types of Nb oxides. Electronic structure changes due to formation of at least three different oxides or mixtures of oxide have been observed. NbO₂ and the NbO oxides seem to form first as a thin protective layer. The pentoxide, Nb₂O₅, is obtained after heavy oxidation. Practical implications of the formation of NbO in the interface between Nb₂O₅ and Nb metal are discussed.