Abstract
In this work, Mn2O3 nanoparticles (NPs) are prepared by co-precipitation technique. The synthesized sample is characterized by X-ray powder diffraction (XRD). The XRD spectrum reveals the cubic structure of Mn2O3 NPs and the lattice parameter is calculated to be 9.4232 ?. Crystallite size (D) is estimated using Debye-Scherer’s formula and is found to be 17.3 nm. A micrograph for the NPs is obtained using Transmission Electron Microscopy (TEM). The Mn2O3 nanoparticles are viewed at 7500× magnification and their shape is spherical. D is also measured using TEM and it is 19.1 nm, which is very close to the one obtained from XRD. The elemental contents of the prepared samples are determined using particle induced X-ray emission (PIXE). In addition, the oxygencontent of the sample is obtained using non Rutherford backscattering spectroscopy (RBS) at 3 MeV proton beam. The sample shows high purity and the RBS technique is more accurate in determining the O-content. The presence of functional groups and the chemical bonding is confirmed by FTIR spectrum. The energy band gap (Eg) is calculated for the NPs using the UV-visible optical spectroscopy between 350 nm and 800 nm and found to be 1.24 eV. The sample shows high absorption in the visible range. The magnetization (VSM) is conducted to the sample and the saturation magnetization (Ms) is calculated as 2.642 emu/g. The hysteresis loop shows antiferromagnetic behavior. The EPR analysis is performed at room temperature for the NPs. The g-factor is calculated from the spectrum and found to be 1.985, and the magnetic field shift occurs at Bo = 350.5 mT. The intensity appeared to be high, which confirms the existence of Mn2+ ions on the surface.
Highlights
Manganese is a transition metal and has many oxidation states (+2, +3, +4) and can give many phases of manganese oxides like MnO, MnO2, Mn2O3, Mn3O4 and Mn5O8
Using Transmission Electron Microscopy (TEM) technique, the shape of Mn2O3 NPs was spherical with D = 19.1 nm and it was very close to the one obtained from X-ray powder diffraction (XRD)
particle induced X-ray emission (PIXE) technique had succeeded in determining the Mn content whereas the oxygen content was well determined by Rutherford backscattering spectroscopy (RBS) technique
Summary
Manganese is a transition metal and has many oxidation states (+2, +3, +4) and can give many phases of manganese oxides like MnO, MnO2, Mn2O3, Mn3O4 and Mn5O8. The first one known as the mineral hausmannite at ambient temperature has a distorted spinel structure and can be represented by the formula Mn2+ Mn32+ O42− [7]. Two polymorphs of this oxide exist, named α and β. According to [13], a Mn3O4 phase, prepared using different precursors, had a very broad particle size distribution ranging from 10 nm to 100 nm. Mn3O4 particles prepared from MnO2 had a tetragonally distorted cubic shape with a size of about 25 to 40 nm. The magnetic properties were studied using VSM and EPR techniques
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