Abstract
•Nano crystalline powder of BaFe0.5Nb0.5O3 (BFN) was obtained by mechanical ball milling technique.•Fine grained pure phase ceramic of BaFe0.5Nb0.5O3 was obtained after spark plasma sintering (SPS) at low temperatures of 1100 °C for 5 min.•SPS BFN ceramic showed colossal relative permittivity (ε′ ~ 2.3 × 104) and low dielectric loss (tanδ ~ 0.48) at room temperature and 1 kHz.
BaFe0.5Nb0.5O3 (BFN) ceramics has been prepared using a rapid process where the powder was synthesised using mechanical milling of the components then consolidated by spark plasma sintering (SPS) for 5 min at 1100 °C. X-ray diffraction results confirmed the pure cubic phase of the prepared SPS BFN ceramic. The average grain size as measured by SEM analysis was ~300 nm. Complex impedance measurements revealed giant dielectric constant (ε′ ~ 2.3 × 104) and low dielectric loss (tanδ ~ 0.48) for the SPS BFN ceramic at room temperature and 1 kHz. Two thermally activated relaxation peaks were observed in the spectra of imaginary part of modulus (M″). These relaxations were attributed to the Debye-like relaxation process in grains (at high frequency and low temperature) and non-Debye Maxwell-Wagner (M-W) polarization effect at grain-boundary (at low frequency and high temperature).