Orientational disorder in the high temperature phase of KCIO4

Neutron diffraction experiments have been performed on a single crystal of the high-temperature phase of KClO 4 at 325 o C and 420 o C. The analysis of the structure factor of Bragg reflections leads to the static orientational probability density function. The positions of the maxima of this function show that ClO 4 − ions have preferred orientations of T d symmetry, with two possible positions. Comparison is made of this result with previous papers. It is also suggested that the ions could reorient between the two potential wells mainly by non-instantaneous rotations around the four-fold axes of the cube Etude d'un monocristal de KClO 4 , dans sa phase a haute temperature, par diffraction de neutrons a 325 et 420 o C. Determination de la fonction statique de densite de probabilite d'orientation a partir de l'analyse du facteur de structure des reflexions de Bragg: les positions des maximums de cette fonction indiquent des orientations privilegiees de symetrie T d , avec deux positions possibles pour les ions ClO 4 − , qui pourraient effectuer des rotations non instantanees autour des axes quaternaires du cube