Influence of Mg2+-substitution on the optical band gap energy of Cr2−Mg O3 nanoparticles

Abstract

Abstract Chromium oxide (Cr2O3) and Magnesium divalent ions (Mg2+) substituted Cr2O3 nanoparticles were synthesized by wet chemical method. In this report, we have investigated the influence of Mg2+ concentration on the structural and optical properties of Cr2O3 nanoparticles. XRD results demonstrated that pristine Cr2O3 nanoparticles exhibit rhombohedral structure and remains unchanged with Mg2+-substitution. However, it results in strained Cr2O3 nanoparticles with a decrease in lattice parameters and cell volume. The most intense peak centered around 534 cm−1 in Raman spectra depicted a considerable shift when Mg2+ is substituted at Cr3+ sites, complementing our XRD results. In addition, UV–Vis absorption investigation revealed marginal decay of optical band gap from 3 eV to 2.76 eV with the increase of Mg2+ concentration. Refractive index and Urbach energy have also been determined from the UV–Vis analysis and their values found to be increase with Mg2+-substitution.