Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Chemistry and Pharmacology
With the use of high-resolution electron microscopy, defects have been observed in crystals of Nb22O54: two types of point defects and extended Wadsley-type defects having a structure corresponding to Nb12O29. For one type of point defect a model is proposed which contains two displaced metal atoms and two interstitial oxygen atoms within a 'block'. For the other, one metal atom and three oxygen atoms are considered to be missing from a tetrahedral site. Contributions made by the three types of defects to the non-stoichiometry of the crystals are discussed.
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