Magnetodielectric properties of rare earth metal-doped BiFeO₃ nanoparticles

Pure and rare earth metal ions (Gd³⁺, Tb³⁺, Dy³⁺)-doped BiFeO₃ nanoparticles have been synthesized by the sol–gel method. The effect of doping of rare earth metal ions on structural, magnetic, dielectric and magnetodielectric properties of synthesized nanoparticles have been investigated. Synthesized nanoparticles have been found to be possessing spherical morphology, with average particle size, 25–46 nm. Structural study confirms that 15 % mole fraction doping of the rare earth metal ions results in structural transformation from rhombohedral to orthorhombic phase. Magnetic study reveals that the synthesized nanoparticles exhibit well saturated ferromagnetic magnetic loops. Dielectric measurements show that doping of rare earth metal ions results in high dielectric constant as compared to that of pure BiFeO₃. Magnetoelectric coupling in the synthesized nanoparticles, established by performing magnetodielectric measurements, reveals that the doped nanoparticles exhibit high magnetodielectric coefficient as compared to its pure form. The high value of saturation magnetization, 5.22 emu/g, dielectric constant, 900 and magnetodielectric coefficient, 5.82 %, have been observed in Dy-doped BiFeO₃ nanoparticles. The observed trend in the properties of the synthesized nanoparticles has been explained on the basis of doping as well as size of the synthesized nanoparticles.