Low-temperature scaling behavior ofBaFe0.5Nb0.5O3

Abstract

The ferroelectric ceramic ${\mathrm{BaFe}}_{0.5}{\mathrm{Nb}}_{0.5}{\mathrm{O}}_{3}$ (BFN) is synthesized by a solid-state reaction technique. The x-ray-diffraction of the sample at room temperature shows a monoclinic phase. The field dependences of the dielectric response and the conductivity are measured in a frequency range from 10 Hz to 2 MHz and in a temperature range from 93 to 213 K. The frequency dependence of the loss peak is found to obey an Arrhenius law with an activation energy 0.12 eV. An analysis of the real and imaginary parts of the dielectric permittivity with frequency is performed, assuming a distribution of relaxation times as confirmed by Cole-Cole plots as well as the scaling behavior of the dielectric loss. The scaling behavior of the dielectric loss spectra suggests that the distribution of the relaxation times is temperature independent. The frequency-dependent electrical data are also analyzed in the framework of the conductivity and modulus formalisms. Both these formalisms provided qualitative similarities in the relaxation times. We observe that the hopping frequency can be used for a scaling of the conductivity spectra for BFN. All these observations clearly suggest that BFN is a relaxor ferroelectric.