Relaxor Behaviour in Pb(Fe0.5Nb0.5)O3

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Authors

  • University Department of Physics, T. M. Bhagalpur University, Bhagalpur-812 007 ,IN
  • University Department of Physics, T. M. Bhagalpur University, Bhagalpur-812 007 ,IN
  • Department of Physics, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata-700 009 ,IN

DOI:

https://doi.org/10.18311/jsst/2008/1905

Keywords:

Relaxor, Dielectric Response, Permittivity, Curie–Weiss Law, Vogel-Fulcher Relation.

Abstract

The relaxor, ferroelectric lead iron niobate, Pb(Fe0.5Nb0.5)O3 (PFN) is synthesized by Coulombite precursor method. Scanning electron micrograph taken at room temperature shows the compactness of the sample. The average grain size is found to be ∼2 μm. The field dependence of dielectric response is measured in a frequency range, 0.1 kHz-1 MHz and in a temperature range from 27°C to 200°C. The temperature dependence of permittivity (ε') shows broad maxima at various frequencies. The frequency dependence of the permittivity maximum temperature (Tm) has been modeled using Vogel-Fulcher relation. Cole-Cole plot confirms the polydispersive nature of the relaxation time. It is proposed that the deviation from Debye behaviour is a result of the development of correlations between polar moments leading to the onset of non-ergodicity near freezing. The results also show that at T > Tm , (1/ε'-1/ε'm) is proportional to the exponent γ and is found to be 1.844 at both 253 and 304 kHz.