Ceramics of a the binary solid solution (1-x)Pb(Mg1/3Nb2/3)O-3-xBi(Zn1/2Ti1/2)O-3 [(1-x)PMN-xBZT] have been prepared with x = 0.10 and 0.15 and examined by dielectric spectroscopy to reveal the temperature dependences of the relaxor ferroelectric behavior. Both compositions studied show a broad and diffuse peak in the temperature dependence of dielectric permittivity epsilon'(T), the temperature of which increases with increasing measurement frequency, indicating the typical relaxor behavior. Detailed analysis of the dielectric response shows that it involves the same types of polarization contributions as the prototypical relaxor Pb(Mg1/3Nb2/3)O-3. One of the contribution to the permittivity arises from the conventional relaxor polarization, chi(CR)*, which can be described by the Kohlrausch-Williams-Watts (KWW) law, P proportional to exp[-(t/tau)(beta)]. It is found that the beta and tau parameters both follow the Vogel-Fulcher law, with the freezing temperature T-f decreasing with increasing BZT content. The change in diffuseness and freezing temperature can be attributed to the increase in chemical disorder because the addition of BZT end member introduces two more heterovalent cations (Zn2+ and Ti4+) on the perovskite octahedral B-site and the Bi3+ cations on the perovskite A-site of PMN. (C) 2011 Elsevier B.V. All rights reserved.