Cluster dynamics in a dipolar glass.

We have directly observed fluctuating dipolar clusters in the defected paraelectric KTa(0.991)Nb(0.009)O(3) using inelastic light scattering techniques for temperatures between 1.8 and 25K and for electric fields up to 2 kV /cm. Together with earlier dielectric relaxation data our data span over nine decades in frequency and obey a Vogel-Fulcher relaxation model with a transition at 3.0K to a glassy dipolar state.