Structural, dielectric behavior, diffuse phase transition, and electrical properties of 0.7(Bi1−xSmx) FeO3–0.3BaTiO3 ceramics (x = 0.1 and 0.2)

Abstract

Environmentally friendly 0.7(Bi1−xSmx)FeO3–0.3BaTiO3 systems with various doping rates with x = 0.1 and 0.2, have been synthesized by the solid-state method, and their structural, microstructural, vibrational, and electrical properties were systematically investigated. X-ray diffraction combined with Rietveld refinement confirmed the stabilization of a single-phase perovskite structure, with lattice contraction attributed to Sm3+ substitution. The BFBT-0.1Sm composition crystallizes in a tetragonal phase with P4/mmm symmetry, whereas the BFBT-0.2Sm sample adopts an orthorhombic structure belonging to the Pmmm space group. This structural evolution is consistently supported by both XRD patterns and Raman spectral analysis. SEM analysis revealed dense microstructures with well-distributed grains. Energy-dispersive X-ray spectroscopy (EDX) confirmed the presence of all the chemical elements constituting the materials. Raman spectroscopy provided evidence of local structural distortion. Dielectric measurements showed a significant increase in permittivity, while impedance and AC conductivity analyses indicated a thermally activated hopping mechanism consistent with Jonscher's power law. The dielectric constant varies with temperature, indicating the occurrence of a diffuse phase transition. This behavior was further analyzed using the modified Curie–Weiss law. A thorough analysis of the dielectric properties as a function of temperature demonstrates a characteristic ferroelectric to paraelectric (FE–PE) transition, marked by a significant rise in the real part of permittivity near 600–700 K for both compounds. This substantial permittivity underscores their potential for energy storage applications. These findings suggest that the studied ceramics are promising candidates for multifunctional devices.