Structural and impedance spectroscopic analysis of Sr/Mn modified BiFeO₃ multiferroics

Glycine + urea are used as fuel agents to synthesize polycrystalline nano-particles of as-burnt Bi_0.9Sr_0.1FeO₃ and Bi_0.9Sr_0.1Fe_1−xMn_xO₃ (x = 0, 0.05, 0.10, 0.15 and 0.20) multiferroic samples using sol–gel auto-combustion method, at relatively low temperature. Structural analysis exhibits the formation of phase pure nano-composites having rhombohedral distorted perovskite structure belonging to space group R3c. Doping of Sr and Mn didn’t disturb the crystal symmetry of the original composite. Field emission scanning electron microscopy revealed that the grains which were initially interlinked with each other became relatively isolated, uniformly distributed and spherical shaped with increasing Mn contents along with increased intergranular porosity. Energy dispersive X-ray spectroscopy confirms the at.% and wt% of all the elements, corresponding to each stoichiometric formula. Dielectric parameters for each sample depict conventional ferrite behavior while hopping of oxygen vacancies contributes a lot in conductivity of the samples. Contribution of grains, grain boundaries and interfaces are evident from impedance spectroscopy. Non-Debye type relaxation is confirmed from the frequency dependent electric modulus and Cole–Cole plots. A solid correlation has been established between electrical properties and microstructure of the samples under investigation.