Synthesis, structural, optical and dispersion parameters of La-doped spinel zinc ferrites ZnFe2-xLaxO4 (x = 0.00, 0.001, 0.005, 0.01 and 0.015)

Abstract

We investigate the structural and optical properties of ZnFe2-xLaxO4 spinel ferrite (0 ≤ x ≤ 0.015) prepared using sol-gel route. The lattice parameter increases and the crystallite size decreases by La3+ replacements as was demonstrated by X-ray diffraction. UV–visible spectroscopy was used to study the optical properties. The optical band gap increases from 1.8714 to 1.9557 eV, with the increase in La3+ concentration up to x = 0.015. On the contrary, Urbach energy (band tail width), EU was found to be decreased from 0.6027 to 0.4247 eV. In addition, different optical parameters were extracted and associated with the change of La amount such as the absorption coefficient, refractive index, the extinction coefficient, real and imaginary dielectric constant, conductivity optical and electrical conductivity. Finally, the dependency of the refractive index to the wavelength was fitted to Wemple-DiDomenico single oscillator model and the parameters like dispersion energy, single oscillator energy, oscillator length strength, and average oscillator wavelength were also determined.