Relaxation and freezing of dielectric response in relaxor   Pb(Mg1/3Nb2/3)O3 crystal
  Dielectric investigations of the relaxor ferroelectric Pb(Mg1/3Nb2/3)O3 crystal were performed in the frequency domain at 10^(-4) 10^5 Hz. In the ergodic relaxor phase two overlapping relaxation processes obeying the Kohlrausch-Williams-Watts law, exp[-(t/tau)^beta], and the Curievon Schweidler law, t^(-n), respectively, were found and parameterized. The values of beta, n and 1/tau tend to zero at 211 K following the Vogel-Fulcher law, pointing to the glassy freezing of the dipole dynamics related to both relaxation processes. 
A. A. Bokov and Z.-G. Ye