Changes in optical properties and structural phases grown upon forming ZnMn2O4/ZnFe2O4 heterostructure nanocomposite

Abstract

The heterostructure nanocomposites (1-x)ZnMn2O4/xZnFe2O4 (x = 0, 0.2, 0.5, 0.8, 1) are formed using the co-precipitation technique. X-ray diffraction and Fourier-transform infrared spectroscopy data disclosed the dissolving of some ions of one phase into the matrix of the other phase. Composite samples with x = 0.5 and 0.8 have an extra ZnO phase and its percentage increased with increased ZnFe2O4 (ZFO) amount in the matrix. The elements constituting the samples and the cations valence state are determined by X-ray photoelectron spectroscopy technique (XPS). The effect of composition parameter (x) on the absorbance spectra, extinction coefficient, refractive index, dielectric constant (real and imaginary), dielectric loss and optical conductivity is investigated by UV diffused reflectance technique. The optical band gap (Eg) of (1-x)ZMO/xZFO (x = 0.2, 0.5) nanocomposite samples was decreased to 2.4, 2.38 while the Eg of nanocomposite sample with x = 0.8 was increased to 2.54 eV. All nanocomposite samples have a normal dispersion similar to ZnMn2O4 (ZMO) sample. ZFO sample exhibited both normal and anomalous dispersion depended on the wavelength range. The 0.2ZMO/0.8ZFO nanocomposite sample exhibited a good nonlinear optical behavior at low frequency. The photoluminescence (PL) intensities of nanocomposite samples are quenched as ZMO alloyed with ZFO. Different emitted colors are observed as the ratio of ZMO and ZFO altered in the matrix.