Effect of sintering temperature on structure and multiferroic properties of Bi0.825Sm0.175FeO3 ceramics

The Bi0.825Sm0.175FeO3 (BSFO) ceramics were prepared by solid state reaction route and the structural, vibrational, and multiferroic properties of these ceramics was studied. The properties of BiFeO3 (BFO) ceramics at higher sintering temperature i. e. 850 °C were compared to that of ceramic at normal sintering temperature (i. e. 830 °C). The Rietveld-refined structure revealed the rhombohedral R3c symmetry in BFO and a mixed phase symmetry (R3c 38.26% + Pnma 61.74%) in BSFO for ceramics sintered at 830 °C. The formation separate phase of SmFeO3 (Pbnm; 12.16%) along with BSFO (Pn21a; 87.84%) phase was observed for ceramics sintered at 850 °C. The small change in sintering temperature led to changes in Raman spectra accompanying abrupt changes in ferroelectric properties. The BSFO shows strong ferromagnetic characteristic due to the spin canting in bulk BFO. The net macroscopic magnetization in bulk BFO due to Sm doping exist due to suppression of spin modulated spiral structure. The BSFO ceramics sintered at 830 °C shows ferroelectric polarization (2Pr) 7.3723 μC/cm2 at an applied field of 15 kV/cm but the BSFO ceramics sintered at 850 °C shows no ferroelectric polarization at room temperature. The presence of magnetization and reasonable ferroelectric polarization at room temperature in BSFO ceramics sintered at 830 °C make this material suitable for multiferroic application.