Diffuse scattering and ordering in the short-range modulated paraelectric phase of sodium nitrite, NaNO₂

Acta Cryst. (2005). B61, 473–480

Contrary to the well known modulated structures with sharp satellite reflections, the diffraction pattern of a short-range modulated structure contains diffuse satellite reflections. The crystal structure of NaNO₂ above T_N = 437.7 K in the paraelectric phase is short-range modulated. The nanodomains elongated in the [001] direction are remnants of distorted fragments of the sinusoidally modulated crystal structure of antiferroelectric NaNO₂. The size of the nanodomains and the range of order decrease with temperature. Above 480 K diffuse satellite reflections are replaced by broad diffuse streaks and the nanodomains become hardly visible.

K. Lukaszewicz, A. Pietraszko and M. Kucharska