Comparison of optical absorption and diffuse reflectance spectra techniques for determining the optical energy band gap of dried and calcined Ni0.5Mn0.5Fe2O4 nanoferrite

Abstract

Ultrafine particles of Ni0.5Mn0.5Fe2O4 were synthesized by coprecipitation technique to study the effect of both physical forms (ferrofluid and powder) and thermal treatment (drying at 100 °C and calcination at 600 °C for two hours) on the structural properties of Ni0.5Mn0.5Fe2O4 nanoferrite. In addition, the work presents a comparison between using optical absorption and optical diffuse reflectance spectra in studying the optical direct energy band gap. x-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to study the phase, size, and morphology of dried and calcined Ni0.5Mn0.5Fe2O4 nanoparticles, respectively. Fourier transform infrared (FTIR) spectra revealed the characteristic peaks of the synthesized ferrite and provided further information on the functional groups. The optical absorption spectra were used to evaluate the optical direct energy band gap of dried and calcined Ni0.5Mn0.5Fe2O4 nanoferrite as a ferrofluid, whereas, the optical diffuse reflectance spectra were used to evaluate the optical direct energy band gap of dried and calcined Ni0.5Mn0.5Fe2O4 nanoferrite in powder form.