Investigation of Relaxor Behavior in Pb(Mg_g1/3Nb_2/3)O₃-PbTiO₃ Thin Films

Abstract

Relaxor properties of 0.7Pb(Mg_1/3Nb_2/3)O₃-0.3PbTiO₃ (PMN-PT) thin films have been analyzed in terms of large frequency dispersion of dielectric response at temperatures below that of the peak permittivity. A wide spectrum of dielectric relaxation was observed in the frequency dependent response of imaginary part of dielectric permittivity. A cumulative response of Debye relaxators was experimentally observed at lower temperatures. The Cole-Cole plots (ϵ′ vs. ϵ″) showed a broad distribution in dielectric relaxation at lower temperatures. The temperature dependence of dielectric dispersion has been analyzed using Vogel-Fulcher relation. A little modification in the Vogel-Fulcher (V-F) relation was incorporated to avoid the singularity at the V-F temperature (T _f ). The activation energy (E) and the freezing temperature in PMN-PT thin films were 40 mV and 400 K, respectively. Investigation of ferroelectric properties in terms of polarization hysteresis behavior confirmed presence of interaction among nanopolar clusters.

Keywords:

• Dielectric relaxation
• relaxor ferroelectrics
• lead titanate
• lead magnesium niobate
• thin films
• polarization hysteresis
• superparaelectric nanopolar clusters