Effect of the solid-state synthesis parameters on the physical and electronic properties of perovskite-type Ba(Fe,Nb)0.5O3 ceramics

Single-phase cubic Ba(Fe,Nb)0.5O3 (BFN) powder was synthesized by solid-state reaction at 900, 1000, 1100, 1200 °C for 4 h in air. X-ray diffraction indicated that the BFN oxide mixture calcined at 1200 °C crystallizes to the pure cubic perovskite phase. The crystallite size of the BFN increases slightly with increasing temperature, while the lattice strain progressively decreases. BFN ceramics were produced from this powder by sintering at 1350–1400 °C for 4 h in air. Samples prepared under these conditions achieved up to 97.4% of the theoretical density. The temperature dependence of their dielectric constant and loss tangent, measured at difference frequencies, shows an increase in the dielectric constant with sintering temperature and measurement frequency which is probably due to disorder on the B site ion of the perovskite. The Mössbauer spectra of these sintered BFN ceramics suggests the presence of a superstructure on the B-cation sublattice.