Investigations on the physical properties of Mn-modified ZnO samples prepared by sol–gel route

Abstract

In this report, we have synthesized successfully sol–gel derived Zn1−xMnxO (x = 0.02, 0.04 and 0.06) nanoparticles to see the effect of Mn doping on structural, optical and magnetic properties of ZnO. The phase purity and structural analysis of all the samples have been made by the X-ray diffraction (XRD) technique with Rietveld refinement using the FullProf software. This study clearly revealed that Mn-doped ZnO nanoparticles exhibit hexagonal wurtzite structure with P63mc symmetry. Lattice parameters found to be increased with Mn doping, this shows that Mn2+ is successfully substituted on Zn2+ sites. The morphology of the nanoparticles was examined by FE-SEM. UV–Vis, FTIR, PL and VSM techniques have been used to see the optical and magnetic response of all the samples. UV–Vis spectra clearly indicate the sharp increment in the band gap energy with Mn doping up to 3.22 eV might be due to the Burstein–Moss effect. FT-IR studies have been utilized to find out the different phonon modes present in the prepared samples. Photoluminescence study revealed a blue shift of the near band emission (NBE) and an increase in the intrinsic defects (viz. VO and OZn) density with increasing Mn concentration up to a certain extent of doping (6%). Magnetic measurement of the Mn doped ZnO samples shows bound magnetic polaron (BMP) induced room temperature ferromagnetism (RTFM) behavior, however, there is suppression of ferromagnetic behavior due to the existence of antiferromagnetic ordering also present in the samples, supported by the Curie–Weiss Law.