Structural and dielectric studies of BaFe_0.5Nb_0.5O₃

Ferroelectric BaFe_0.5Nb_0.5O₃ (BFN) ceramic is synthesized by the solid-state reaction technique for the first time. The x-ray diffraction of the sample at room temperature shows a monoclinic phase. Dielectric studies of the sample show a frequency dependence of the temperatures at which the dielectric permittivity (real and imaginary) peaks. The temperature variations of the real and imaginary components of the dielectric permittivity show broad maxima. There is evidence for Vogel-Fulcher-type relaxational freezing. The analysis of the real and imaginary parts of the dielectric permittivity with frequency has been performed assuming a distribution of relaxation times as confirmed by Cole-Cole plots as well as the scaling behaviour of the dielectric loss. All these observations clearly suggest that BFN is a relaxor ferroelectric. The Mössbauer spectrum of the sample at room temperature shows a symmetric doublet, with the iron being trivalent.