Beiträge zur Untersuchung anorganischer nichtstöchiometrischer Verbindungen. XIII. Oxydationsprodukte von monoklinem Nb12O29 Elektronenoptische Untersuchung

Contributions to the Investigation of Inorganic Non-stoichiometric Compounds. XIII. Oxidation Products of Monoclinic Nb₁₂O₂₉, Electron Optical Investigation The electron optical investigation shows that the starting material Nb₁₂O₂₉(mon.) is well ordered and that the oxidation products Nb₂O₅(Ox1BI) and Nb₂O₅(Ox2BI) have different structures. Nb₂O₅(Ox1BI) has a similar structure as Nb₁₂O₂₉(mon.), however differs from the latter by characteristic point defects, which in the electron microscope easily disappear by reduction. Nb₂O₅(Ox2BI) has not a well ordered structure; characteristic are rows of [2×n]-blocks which on the average are separated by five [3×n]-blocks. The average block length is n = 4 octahedra. The observed composition O/Nb = 2.500 can be explained by a structure model with unoccupied tetrahedral sites of Nb.