Solvent mediated phase stability and temperature dependent magnetic modulation in BiFeO3 nanoparticles

•Bismuth iron oxide (BiFeO3) nanoparticles were synthesized using sol-gel method.•Two solvents (acetic acid ‘AA’ & ethylene glycol ‘EG’) were used during synthesis.•Pure BiFeO3 phase is obtained at 200 °C calcination temperature using AA.•EG lead to formation of pure BiFeO3 under as-synthesized and calcined conditions.•Raman bands corresponding to both E(TO) and A1 (TO) showed BiFeO3 phase.•Presence of ferromagnetic domains was confirmed using FC/ZFC curves. Phase-pure bismuth iron oxide nanoparticles are reported for the first time based on selection of solvent, during sol–gel synthesis, under as-synthesized conditions and without using any stabilizing agent. Two solvents are being used during sol synthesis i.e. acetic acid and ethylene glycol. Nanoparticles prepared using acetic acid as solvent result in amorphous behavior under as-synthesized conditions, whereas BiFeO3 phase is obtained after calcination at 200 °C. Mixed BiFeO3 and Bi2Fe4O9 phases are obtained for nanoparticles calcined at 300 °C. Nanoparticles prepared using ethylene glycol as solvent result in phase pure BiFeO3 even under as-synthesized conditions and this phase persists after calcination up to 300 °C. Presence and stability of Raman bands corresponding to both E(TO) and A1(TO) show BiFeO3 phase. Nanoparticles with diameter of ~15 nm prepared using ethylene glycol as solvent result in ferromagnetic behavior with saturation magnetization of 9.1 emu/g under as-synthesized conditions due to modulation of spiral spin structure. Decrease in magnetic anisotropy constant is observed with increase in calcination temperature. FC/ZFC curves indicate presence of ferromagnetic domains at 80–300 K and cusp in FC/ZFC data is attributed to pinning of magnetic domains. These interesting properties are useful for advanced applications of bismuth ferrite that is also popular as a multiferroic material.