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The system chromium trifluoride‐niobium pentoxide and Defect Structures
Author(s) -
Hutchison J. L.,
Lincoln F. J.,
Anderson J. S.
Publication year - 1976
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.19764220302
Subject(s) - isostructural , electron microprobe , crystallography , niobium , solid solution , trifluoride , materials science , annealing (glass) , chromium , powder diffraction , lattice (music) , chemistry , crystal structure , inorganic chemistry , mineralogy , metallurgy , physics , acoustics
The system CrF 3 Nb 2 O 5 has been examined by the methods of lattice imaging electron microscopy, in the expectation that Cr 3+ and F − would build into the ReO 3 ‐derived structure to generate compounds analogous to those found in the system WO 3 Nb 2 O 5 . For three compositions studied (CrF 3 : Nb 2 O 5 = 1:1, 1:6, and 4:13), the chief product was isostructural with NNb 2 O 5 . X‐ray ultra microprobe analysis of crystalline regions, completely characterized by electron diffraction and lattice imaging, confirmed that the Cr : Nb ratio agreed with the made‐ up composition, and the product is a solid solution phase Cr x Nb 16−x O 40−2x F 2x . Fluorine was lost during preparation by a pyro‐ hydrolysis reaction. No analogues of the WO 3 Nb 2 O 5 compounds were found, and the NNb 2 O 5 solid solutions were notably free from laminar intergrowths of other block structures. However, they contained disordered domains representing fluctuations of composition, with defect structures of types not hitherto observed. These unambiguously indicated local enrichment in CrF 3 , resisting prolonged annealing.