Room temperature ferromagnetism and photoluminescence of multifunctional Fe doped BaZrO3 nanoceramics

Abstract

Nanoceramics samples of BaZr1-xFexO3 (where, x = 0.00, 0.05, 0.10, 0.20, 0.30, 0.40 and 0.50) were prepared through sol-gel auto combustion method and structural, microstructural, magnetic and optical properties have been investigated. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopic measurements showed that the synthesized samples have a cubic perovskite structure. More emphasis was given for calculating accurate values of average crystallite size (D) and lattice parameter (a) by Williamson-Hall (W-H) analysis and Nelson-Riley extrapolation function (N-R) respectively. The average crystallite size (D) calculation shows that the crystallite size of the prepared samples was in the nano-regime. The surface morphology of grains of the present samples was examined using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Compositional stoichiometry was confirmed by energy dispersive spectrum (EDS) analysis. The pure BaZrO3 prepared exhibits diamagnetism. Magnetism observed in doped compositions was significantly depended upon Fe ion concentration. With increasing Fe ion concentration, the concentration of oxygen vacancies was increased and as a result of which enhanced magnetic properties was observed. Simultaneously, magnetization of doped compositions was enhanced with increasing of Fe ion concentration. This incongruity in the magnetic behavior can be explained in terms of the changes in the oxidation state exchange interactions of ions such as the Fe3+-to-Fe4+ change induced by oxygen vacancies. The divergence was observed in the temperature dependence of the field cooling (FC) and zero-field cooling (ZFC) magnetization curves, indicating a spin-glass behavior arising from the mixing of ferromagnetic and antiferro-magnetic phases. The ferromagnetic properties are predominant below 50 K and increases with the Fe doping concentration. UV–visible absorption spectra showed that absorption edge shifted to higher wavelength with increasing Fe concentration while corresponding energy band gap of the prepared nanoceramics decreases with increasing Fe concentration. The photoluminescence (PL) properties were significantly dependent on the Fe concentration and a strong violet-green emission for pure BaZrO3 sample was observed.