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Ordering of Interstitial Impurities in Niobium
Author(s) -
van Landuyt J.,
Gevers R.,
Amelinckx S.
Publication year - 1966
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.19660130218
Subject(s) - superlattice , niobium , materials science , condensed matter physics , electron diffraction , annealing (glass) , diffraction , crystallography , oxide , stacking , niobium oxide , impurity , chemistry , optics , metallurgy , nuclear magnetic resonance , physics , organic chemistry
The ordering phenomenon in niobium is studied by electron microscopy and by electron diffraction. The phenomenon is found in parts of niobium foils subjected to an annealing treatment in vacuum. Domains are formed which, on the basis of the present model, are due to the ordering of interstitial oxygen atoms. The insertion of the interstitials on a superlattice in the nobium matrix causes a deformation of the latter in a 〈110〉 direction. The domain structure results from the fact that several orientations are possible for the superlattice. Further evidence for this ordering is deduced from the presence of superlattice dislocations and of supplementary spots in the diffraction patterns. The superlattice is deduced from the diffraction data and a composition Nb 2 O is attributed to this metallic oxide phase. The domains are revealed by fringe contrast at the boundaries and by the change in background intensity. Both contrast effects are associated with the slight deformation due to the ordering. A discussion is included of a second type of fringe pattern which is often observed in annealed niobium. Patterns of this type have previously been attributed to the presence of stacking faults; it is shown here that they are due to plate‐shaped precipitates of some oxide phase in the niobium matrix.