Freezing of polarization dynamics in relaxor ferroelectric (1−x)Pb(Mg₁/₃Nb₂/₃)O₃−xBi(Zn₁/₂Ti₁/₂)O₃ solid solution
2011
Tailor, H.N. | Bokov, A.A. | Ye, Z.-G.
Ceramics of a the binary solid solution (1−x)Pb(Mg₁/₃Nb₂/₃)O₃−xBi(Zn₁/₂Ti₁/₂)O₃ [(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 ɛ’(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)O₃. One of the contribution to the permittivity arises from the conventional relaxor polarization, χCR ∗, which can be described by the Kohlrausch–Williams–Watts (KWW) law, P∝exp[−(t/τ)ᵝ]. It is found that the β and τ parameters both follow the Vogel–Fulcher law, with the freezing temperature Tf 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.
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