Characterization of oxygen dynamics in ZrW2O8.

Abstract

The dynamics of oxygen motion in ZrW2O8 have been characterized using O-17 solid-state NMR. Rates of dynamic exchange have been extracted from magnetization transfer experiments over a temperature range of 40 to 226 degrees C, and distinct values for the associated activation barrier have been observed on either side of the order/disorder phase transition at similar to 175 degrees C. A detailed model for the dynamical process is proposed, which reconciles the observation of continuing oxygen dynamics in the low-temperature phase with the static order implied by earlier X-ray diffraction studies.