Control the nanostructured growth of manganese oxide using starch: Electrical and optical analysis

Abstract In this work, the influence of starch on the structure, and consequently, the properties of manganese oxide have been investigated at room temperature. Different weights of starch have been added to manganese nitrate during a solid-state combustion process. All the samples have been annealed at 600 °C for 2 h. The XRD (X-ray diffraction) and FT (Fourier transform)-Raman spectroscopy have shown the formation of α-Mn2O3 cubic structure for weight ratio equal to or less than (1/5) of starch/ Mn(NO3)2, while above this amount the phase changed to tetragonal phase Mn3O4. The crystallite size calculated via the Scherer equation is ranged from 21.3 nm to 23.8 nm. The strain and the dislocation density have values in the order of 10−3. SEM (Scanning Electron Microscope) indicates a discrepancy in the size and the form of the particles due to the effect of starch weights. The sizes of spherical nanoparticles vary in the range of 780 nm - 30 nm. The energy gap estimated from the theory of Kubelka-Munk is reduced from 3.45 eV to 1.75 eV due to the effect of 0 and 0.5/5 ratio of starch/ Mn(NO3)2 and increased again to 2.63 eV for Mn3O4. Also, the dielectric permittivity has been influenced by starch weight. The electrical conductivity depends on the frequency and complies with the universal power law of Jonscher. Mn3O4 nanoparticles have been synthesized at low temperatures with a high percentage of low-cost starch with improved characteristics. Therefore, it is a promising material for the production of lithium manganese oxide to be employed in batteries of lithium.