Lead-free perovskite Ba(Al 1/2 Nb 1/2 )O 3 was prepared by conventional ceramic fabrication technique at 13501C/5 h in air atmosphere. The crystal symmetry, space group and unit cell dimensions were determined from the experimental results using FullProf software whereas crystallite size and lattice strain were estimated from Williamson-Hall approach. X-ray diffraction analysis of the compound indicated the formation of a singlephase monoclinic structure with the space group P2/m. EDAX and SEM studies were carried out in order to evaluate the quality and purity of the compound. Permittivity data showed lowtemperature coefficient of capacitance (T CC 5 14%) up to 1001C. To find a correlation between the response of the real system and idealized model circuit composed of discrete electrical components, the model fittings were presented using the impedance data. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type. The correlated barrier-hopping model was used to successfully explain the mechanism of charge transport in Ba(Al 1/2 Nb 1/2 )O 3 .

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A new lead‐free perovskite ceramic Ba(Bi1/2Nb1/2)O3 was prepared by a conventional ceramic technique at 1185 °C in oxygen atmosphere. X‐ray diffraction analysis of the compound indicated the formation of a single‐phase monoclinic structure. Dielectric study revealed a diffuse phase transition at 340 °C. Cole–Cole analyses suggested the dielectric relaxation to be of non‐Debye type. Electric modulus studies supported the hopping type of conduction in Ba(Bi1/2Nb1/2)O3. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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:The relaxor ferroelectric lead iron tantalate, Pb(Fe 0.5 Ta 0.5 )O 3 (PFT) is synthesized by Coulombite precursor method. The X-ray diffraction pattern of the sample at room temperature shows a cubic phase. The field dependence of dielectric response is measured in a frequency range 0.1 kHz -1 MHz and in a temperature range from 173-373 K. The temperature dependence of permittivity (ε ′) shows broad maxima at various frequencies. The frequency dependence of the permittivity maximum temperature (T m ) has been modelled using Vogel-Fulcher relation.

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