Direct observation of point defects in Nb₁₂O₂₉ by high-resolution electron microscopy

Point defects have been observed directly in non-stoichiometric niobium oxides, Nb₁₂O₂₉, by high- resolution electron microscopy at a resolution of 3-4 Å. A proposed model for the point defect is a complex composed of two interstitial metal atoms and two interstitial oxygen atoms. Observations have been made on the annealing out of these defects under electron irradiation. Evidence on the density of these defects offers a semi-quantitative explanation of how the non-stoichiometric oxygen excess in these oxides is accommodated in the matrix structure.