Multiferroic properties of Sr-doped BiFeO3 nanoparticles

Highlights: • Manuscript conducts systematic study of magnetic as well as electric properties of Sr-doped BiFeO₃ nanoparticles. • Particle size dependent study. • Nèel temperature is determined for the Sr-doped BiFeO₃ nanoparticles. - Abstract: The effects of 'Sr-doping' and 'particle size' on multiferroic properties of BiFeO₃ nanoparticles were studied. Structural analysis revealed no influence on the rhombohedral structure of BiFeO₃ with Sr-doping in the synthesized nanoparticles. The particle size of Sr-doped BiFeO₃ nanoparticles was tailored by varying calcination temperature. The crystallite size got reduced with Sr-doping and also on decreasing the calcination temperature. Lattice strain was observed to enhance with reducing particle size of Sr-doped BiFeO₃ nanoparticles. Magnetic measurements confirmed enhancement in magnetization via suppression of spin cycloidal structure with Sr-doping owing to creation of oxygen vacancies, enhanced lattice strain and reduction in particle size. Dielectric analysis revealed deterioration of dielectric constant of BiFeO₃ with Sr-doping due to the formation of oxygen vacancies. Further, on reducing particle size of Sr-doped BiFeO₃ nanoparticles, both saturation magnetization and dielectric constant values registered increase. Lowering of the magnetic phase transition temperature with particle size of Sr-doped BiFeO₃ nanoparticles indicated weakening of magnetic exchange interactions.