N-15 NMR-STUDY OF THERMALLY CYCLED KCN PELLETS

(KCN)-N-15 powder has been pressed into pellet and studied under thermal cycling. A previous x-ray-diffraction study indicates that this sample treatment introduces random strain fields, which suppress the usual noncubic low-temperature phases and lead instead to a quadrupolar glass state in surface regions of the sample during some temperature cycles. We have attempted to observe this behavior in the bulk, by monitoring the CN rotational motions using the N-15 NMR line shape. We find the line shapes to be identical to those obtained from raw KCN powder. A sharp transition from the rotor phase to an orientationally static phase was always observed, with negligible hysteresis. The line shapes did not exhibit the continuous broadening typical of quadrupolar glass-forming systems.