International
Tables for Crystallography Volume D Physical properties of crystals Edited by A. Authier © International Union of Crystallography 2006 |
International Tables for Crystallography (2006). Vol. D. ch. 3.1, p. 369
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Figure 3.1.5.19
Structure of sodium nitrite, NaNO2. The molecularly bonded NO2 ions are shaped like little boomerangs. At high temperatures they are randomly oriented, pointing up or down along the polar b axis. At low temperatures they are (almost) all pointed in the same direction ( or domains). Over a small range of intermediate temperatures their directions have a wave-like `incommensurate' modulation with a repeat length L that is not an integral multiple of the lattice constant b. |