Ferromagnetic, electric, and ferroelectric properties of samarium and cobalt co-doped bismuth ferrite nanoparticles

Abstract

Pure and co-doped multiferroic bismuth ferrite (BFO) nanoparticles were synthesized by the sol-gel method. Samarium and cobalt were used as co-dopants in BFO. The co-doped composites had the formula Bi1-xSmxFe1-yCoyO3, where x = 0.1 and y = 0.05, 0.1, or 0.15. Rietveld refinement of X-ray diffraction patterns showed a well-arranged crystalline rhombohedral structure with space group R3c. The rhombohedral structure transformed to an orthorhombic structure with space group Pbam in co-doped BFO nanoparticles. The ferromagnetic properties of synthesized nanoparticles were investigated in detail. Bi0.9Sm0.1Fe0.85Co0.15O3 showed a large increase in saturation magnetization and remanent magnetization to 3.2 and 1.5 emu/g, respectively. The large increase in magnetization with a reasonable squareness ratio and coercive field of co-doped BFO nanoparticles means they have potential uses in memory and spintronic devices. Electric properties such as resistance, reactance, AC resistivity, and AC conductivity were analyzed as a function of frequency. The AC resistivity decreased and the AC conductivity increased greatly with increasing co-dopant concentration. The ferroelectric behavior of pure and co-doped samples was also investigated. The maximum polarization and remanent polarization greatly increased to 12.5 and 7.5 μC/cm2, respectively, in Bi0.9Sm0.1Fe0.85Co0.15O3. The increased conductivity and reduced resistivity of co-doped samples may also be useful in efficient photovoltaic solar cells.