Structural and Optical Properties of Annealed MnO2 Powder Synthesized by Hydrothermal Method

Abstract

By using a homogenous solution that consists of hydrochloric acid (HCl), potassium permanganate (KMnO4), and deionized water, manganese dioxide (MnO2) nanopowder was synthesized. Scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscope (AFM), and UV-vis. spectroscopy measurements have been used for describing the surface morphology and structure regarding MnO2 nanopowder at various annealing temperatures in a 250-700C range for 120mins. The temperature of XRD data for MnO2 powder annealed at various temperatures revealed the development of a tetragonal phase of nanowires with high plane intensity (211). With an increase in annealing temperature (from 135.230 to 155.119Ǻ), the lattice constant drops. AFM revealed that when annealing temperatures rose, MnO2 grain size increased (from 52.62-69.62 nm). The optical characteristics, transmittance of MnO2 NPs at annealing temperatures 550°C have a high transparent approach to (72%), and Energy gap reduces with increasing annealing temperature in the range (1.5 to 1.1 eV).