Manganese oxides synthesized via microwave-assisted hydrothermal method: phase evolution and structure refinement

Manganese oxides were synthesized during 40 min at 140 ºC via Microwave-Assisted Hydrothermal (MAH) method and treated different temperatures in order to evaluate the phase evolution using structure refinement (Rietveld method). The samples obtained heat defined by means of thermal analysis (160 ºC, 480 715 870 920 1150 ºC) analyzed X-Ray Diffractometry (XRD), Fluorescence (XRF), Fourier Transform Infrared (FTIR) spectroscopy, Raman scattering, UV-Vis absorption Scanning Electron Microscopy (SEM). Structural characterizations allowed identify five distinct phases: α-MnO2, Mn3O4, Mn5O8, Na2Mn5O10 Na4Mn9O18 with weight percentages dependent on treatment. hausmannite (average crystallite size ranging from 28.9 nm 99.1 nm) is present all go through various oxidation reduction processes 160 without any major variation lattice parameters. Chemical identifies presence Na+ ions samples, either as substitution defects or components specific crystalline structures (Na2Mn5O10 Na4Mn9O18), showing that manganese works intercalation compounds, important materials for energy storage devices optimization. results presented enables a better interpretation structural characteristics MAH.