Influence of Mn doping on microstructure, optical, dielectric and magnetic properties of BiFeO3 nanoceramics synthesized via sol-gel method

The present work embodies studies on the structure, optical, electrical and magnetic properties of BiFe1-xMnxO3 (0 <= x <= 0.06) nanoceramics synthesized through sol-gel process. The prepared compositions were examined through several analytical techniques. Rietveld refinement analysis of the x-ray diffraction (XRD) data confirms rhombohedral crystal structure with R3c space group for all the samples and the crystallite size varies in the range of 14-17 nm. Electron microscopy (SEM/TEM)) images exhibit non-uniform surface morphology and agglomerated nature of the nanoparticles. The elemental compositions were established from energy dispersive x-ray (EDX) analysis. The bending/stretching vibration modes in the samples have been identified through Fourier transform infrared (FTIR) spectroscopy. A slight variation in the optical band gap is observed with the Mn doping. Frequency dependent dielectric measurements at room temperature reveal maximum value of the dielectric constant for 4% Mn doped BiFeO3 at lower frequencies. The magnetic hysteresis (M-H) loops at room temperature show ferromagnetic nature of all the prepared samples associated with the Jahn Teller distortion of MnO6 octahedron. A suppression in the saturation magnetization is observed for the higher Mn concentration samples. Thus, the appropriate doping of Mn ions can improve the dielectric and magnetic properties of the BiFeO3 system.