Abstract
The relaxor, ferroelectric lead iron niobate, Pb(Fe 0.5 Nb 0.5 )O 3 (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 (e ' ) shows broad maxima at various frequencies. The frequency dependence of the permittivity maximum temperature (T m ) 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 > T m , (1/e ' -1/e ' m ) is proportional to the exponent γ and is found to be 1.844 at both 253 and 304 kHz.
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