Structural, morphological, and dielectric properties of lead-free BaFe1/2Nb1/2O3 based ceramics: toward a deeper understanding of the dielectric mechanisms

The barium iron niobate material BaFe 1/2 Nb 1/2 O 3 (BFN) was prepared using the solid-state reaction route. At room temperature, the Rietveld refinement technique showed a cubic phase with the space group Pm 3 ¯ m . In the low temperature range, the conductivity (versus frequency) followed the double power law. An appropriate model is used to obtain the electrical parameters related to such relaxations. The BFN ceramic showed two dielectric relaxations in the temperature ranges 170–325 K and 400–520 K. Most interestingly, a high permittivity value is obtained with a low dielectric loss (0.14) at room temperature. To better understand the physical mechanisms of these materials, we used a model based on the combined effect of polarons and conductive charge carriers. The importance of this study lies in its ability to distinguish the contributions of localized and conductive charge carriers, also explaining the permittivity plateau near room temperature.