An Electron Diffraction and Crystal Chemical Investigation of Oxygen/Fluorine Ordering in Niobium Oxyfluoride, NbO2F

✍ Scribed by Frank J. Brink; Ray L. Withers; Lasse Norén

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 379 KB
• Volume: 166
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2002.9562

✦ Synopsis

A careful electron di4raction study of the ReO 3 -type oxy6uoride NbO 2 F has revealed the presence of characteristic transverse polarized planes of di4use intensity running through the G ؎ 1hk 1 3 2* regions of reciprocal space as well as continuous rods of di4use intensity running through the G ؎1 1 2 1 2 2* regions of reciprocal space. The continuous planes of di4use intensity in reciprocal space (perpendicular to each of the major crystal directions a, b and c) imply the existence of one-dimensional, oxygen/6uorine-ordered columns of atoms along 10012 in real space but with no lateral correlation in the ordering from such 10012 column to the next. The continuous lines of di4use intensity along the 1 1 2 1 2 2* directions of reciprocal space are ascribed to Rigid Unit Mode (RUM) rotations of the constituent MX 6 octahedral framework. A combination of bond-valence arguments and simple structure factor calculations are used to support this argument.

2002 Elsevier Science (USA)