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

Bi(1-x)TbxFeO3(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)TbxFeO3 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.