Neutron diffraction study of orientational freezing in TlNO2 and CsNO2

The low-temperature crystal structure and temperature dependence of lattice parameters and atomic mean-square displacements of thallium nitrite (TlNO2) and cesium nitrite (CsNO2) have been determined by neutron powder diffraction. Previously, based on specific heat and dielectric relaxation measurements, both compounds were reported to exhibit partial dynamic orientational disorder of the NO2 anions below the transition temperatures 282.4 and …