Low Temperature Dielectric Relaxation in Ba1−xBixTi1−x

We report on dielectric properties of polycrystalline Ba1−xBixTi1−xFexO3 (BBTF) ceramic system (x=0.02, 0.06, 0.08, 0.10, 0.12, and 0.16). The materials were synthesized by solid state ceramic route. Solid solution formation has been confirmed by powder X-ray diffraction for compositions with x≤0.16. Crystal structure is tetragonal for x≤0.08 and cubic for x≥0.10. Microstructures show that the average grain size is less than one micrometer (1 μ). Dielectric behavior has been studied as a function of temperature (100 K–400 K) and frequency. Composition with x=0.02 exhibits diffuse phase transition. Compositions with x≥0.10 show ferroelectric relaxor behavior. This shows that diffuse ferroelectric transition behavior changes to relaxor type ferroelectric transition with increasing x. Plots of dielectric loss (D) versus temperature shows broad maxima which shift to high temperature with increasing frequency, dispersion in dielectric loss decreases with x below peak maxima and increases above. It may be attributed to Maxwell Wagner type relaxation process for low x (~0.02) and relaxation of nanopolar regions for x=0.16