Magnetic characterization of nano-sized terbium doped bismuth ferrite synthesized by sol-gel method

Abstract

Bi_(1−x)Tb_xFeO₃ (x = 0, 0.03, 0.04, 0.06, 0.09, 0.12) nanoparticles are prepared by sol-gel method. X-ray diffraction analysis shows the formation of perovskite structure in the synthesized samples and crystallite sizes in the range of 15 nm. The perovskite structure together with the presence of a strong absorption peak observed at 545 cm⁻¹ in the Fourier Transform Infrared Spectroscopy measurements, characteristic of FeO₆ octahedral, confirms the formation of single phase BiFeO₃ structure. The cycloidal spin nature of BiFeO₃ is said to be suppressed in particles that are less than 62 nm across enhancing the ferromagnetic signature. The magnetic behaviour of the Bi_(1−x)Tb_xFeO₃ nanoparticles is found to change anomalously with change in Tb doping. Vibrating-sample magnetometer studies reveal a maximum in the magnetic moment for a Tb doping concentration of x=0.03 with clear ferromagnetic order at room temperature. With increase in x beyond 0.03, magnetization decreases, while a further increase beyond x=0.04 once again increases the magnetization. Room temperature Mossbauer spectroscopy reveals the presence of a paramagnetic doublet and a sextet, the variation of whose relative ratios is in corroboration with the magnetization studies.