Phase evolution, magnetic and electrical properties in Sm-doped bismuth ferrite

In this paper, we report on the effect of Sm doping on the phase evolution and properties of phase-pure Bi1−xSmxFeO3 (BSFO) ceramics synthesized via a conventional solid-state-reaction method. We find that upon calcination, Sm doping of bismuth ferrite promotes the formation of perovskitic phase and leads to the elimination of the secondary phases. On the other hand, undoped compositions do not yield completely phase-pure samples and contain secondary phases such as Bi25FeO40. Differential thermal analysis corroborates the sequence of phase evolution as examined from the x-ray diffraction patterns. A thermodynamic analysis, based on the bond energy, has been carried out to explain the effect of doping on the stabilization of perovskite structured phase upon Sm doping and is well supported by the thermal analysis results. Vibrating sample magnetometry measurements show that BSFO samples possess higher room temperature remnant magnetization than the undoped samples. Temperature dependent magnetic measurements suggest an antiferromagnetic behavior in the BSFO samples with a Néel temperature of ∼370°C, absent in the undoped samples. Mössbauer spectroscopy on Sm-doped specimens reveals the presence of phase-pure BSFO with absence of any Fe+2 ions. Interestingly, doped samples exhibit an order of magnitude increase in the leakage current density.