Exploring the Effect of Fe/Cr Doping on Structural and Optical Characteristics of Nano ZnMn<inf>2</inf>O<inf>4</inf>

Abstract

Iron or chromium doped nano ZnMn2O4 samples (ZnMn2−xFexO4 or ZnMn2−xCrxO4, x = 0, 0.1, 0.15, 0.2) were prepared by the sol-gel procedure. Rietveld method analysis applied for Synchrotron x-ray diffraction data revealed single phase ZnMn2O4 (ZMO) tetragonal phase for the samples. The variation in the lattice parameters and crystallite size of different samples upon doping are discussed. X-ray photo-electron spectroscopic (XPS) technique was used to verify the incorporation of doped elements in ZMO matrix and to determine the cation oxidation states. All samples absorb light in wavelengths longer than 500 nm, demonstrating that they can efficiently absorb light in the visible range. Fe or Cr modified the light absorbance characteristics of ZMO sample. The sensitivity of ZMO sample to the daylight was increased as it doped with either Fe or Cr. The optical band gap energy, the photoluminescence intensity and the emitted colors from ZMO sample were affected by the kind of dopant element and the doped concentration. The behavior of extinction coefficient, dielectric constant (real and imaginary) and the optical conductivity of all samples were also explored. Fe or Cr doped samples exhibited a paramagnetic behavior. The small dielectric value and the relative small bandgap nominated the doped materials to be used in optoelectronic applications.