PHASE-TRANSITION AT 160 K IN KNO2

The phase transition of KNO2 at 160 K was confirmed in terms of the ch ange of charge distribution between sigma(NK) bond and sigma(NO) bond. The variation of the charge density as a function of temperature is i n good agreement with previous reports of the phase transition. This p hase transition is due to the order-disorder reorientation which arise s from the translational motion of K+ along the c-axis and the flippin g motion of NO2- around the b-axis. The phase transition of KNO2 at 16 0 K is attributed to the flipping motion of NO2- groups. (C) 1998 Else vier Science B.V. All rights reserved.