The dynamics of polarization switching have been investigated over extremely broad time (10(-8)<t<10(2) s) and field ranges for (001)(c), (110)(c), and (111)(c)-oriented Pb(Zn1/3Nb2/3)O-3-4.5%PbTiO3 crystals. The results demonstrate the presence of broad relaxation time distributions that can extend over a decade(s) in orders of magnitude in time, and which sharpen significantly with increasing field. The polarization transients have been fit to stretched exponential functions, which are typical of disordered systems. (C) 2004 American Institute of Physics.