Lead free perovskite Ba(La 1/2 Nb 1/2 )O 3 was prepared by conventional ceramic fabrication technique at 1375uC for 7 h in air atmosphere. The crystal symmetry, space group and unit cell dimensions were estimated using Rietveld analysis. X-ray diffraction analysis indicated the formation of a single phase monoclinic structure with space group P2/m. Energy dispersive X-ray analysis and scanning electron microscopy studies were carried to study the quality and purity of the compound. Permittivity data showed low temperature coefficient of capacitance (T CC 511%) up to 100uC. The circuit model fittings were carried out using the impedance data to find the correlation between the response of real system and idealised model electrical circuit. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type. The correlated barrier hopping model was employed to successfully explain the mechanism of charge transport in Ba(La 1/2 Nb 1/2 )O 3 . The AC conductivity data were used to evaluate the density of states at Fermi level, minimum hopping length and apparent activation energy.

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Lead-free Ba(In 0.5 Nb 0.5) 1-x Ti x O 3 (0 ≤ x ≤ 1) ceramics was synthesized using a standard high temperature solidstate reaction method and sintered at 1400°C/4 h (except the pure BaTiO 3 which was sintered at 1300°C/4 h). The ceramics was characterized by X-ray diffraction, scanning electron microscopy, dielectric, impedance and AC conductivity studies. The crystal structure of the compounds was found to be cubic (with the space group Pm3m) for x = 0, 0.25 and 0.50 and tetragonal (P4/mmm) for x = 0.75 and 1.0. Increase in Ti-content in the ceramic samples leads to the decrease in unit cell volume while the values of real as well as imaginary parts of dielectric constant and AC conductivity increase. Complex impedance spectroscopy analysis indicated the negative temperature coefficient of resistance. AC conductivity data supported the hopping type of conduction in the system and obeyed Jonscher's power law. The real and imaginary parts of dielectric constant and AC conductivity data fit excellently well with an exponential function.