Structural, optical and magnetic properties of multiferroic (1−x)BiFeO3xPbTiO3 nanoparticles

• Synthesis of (1−x)BiFeO3xPbTiO3 nanoparticles (0.1 ≤ x ≤ 0.5).
• The structural transformation from rhombohedral (R3c) to tetragonal structure (P4mm).
• Strong absorption of visible light with a small optical band gap (1.81–2.69 eV).
• Improved magnetic behavior indicating the suppression of cycloid spin structure of BiFeO3.
• May be useful for memory, optoelectronics and spintronics.

We report structural, optical and magnetic properties of single-crystalline (1−x)BiFeO3xPbTiO3 (BF-xPT) solid solution nanoparticles synthesized by a facile sol–gel method in the compositional range of 0.1 ≤ x ≤ 0.5. It was observed that the substitution of PbTiO3 (PT) in BiFeO3 (BF) not only suppresses the impurity phases but it also improves the structure stability of perovskite phase. X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterization confirmed the high purity of the nanoparticles and the structural transformation from rhombohedral (space group: R3c) to tetragonal structure (space group: P4mm) with increasing x. The average particle size was estimated to be around 29–47 nm from TEM and XRD analysis and size decreases with increasing x. The optical study shows that the band gap of BF-xPT nanoparticles, as measured from UV–visible absorption profiles, increases 1.81–2.69 eV as x increases from 0.1 to 0.5, indicating their usefulness as the photovoltaic material and photocatalyst. The magnetic measurements exhibited the improved magnetic behavior with the remnant magnetization values of Mr ≤ 0.025 emu/g, indicating the suppression of the cycloid spin structure of BiFeO3.