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

Figure 3.1.5.19 

J. F. Scottc*
[Figure 3.1.5.19]
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 ([+b] or [-b] 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.